Stephanie Law, University of Delaware
Viktoriia Babicheva, ITMO University
Svetlana Boriskina, Massachusetts Institute of Technology
Frank Neubrech, University of Heidelberg
EM03.01: Semiconductor Resonators and Metasurfaces
Monday PM, November 27, 2017
Hynes, Level 1, Room 104
8:30 AM - *EM03.01.01
Mie-Resonant Semiconductor Metasurfaces—Active Tuning, Light Emission and Nonlinear Effects
Isabelle Staude 1 Show Abstract
1 Institute of Applied Physics, Friedrich Schiller University Jena, Jena Germany
Metasurfaces composed of high-index semiconductor nanoresonators provide a powerful platform for controlling the generation and propagation of light . Most prominently, it is well established that semiconductor metasurfaces can impose a spatially variant phase shift onto an incident light field, thereby providing control over its wave front with high transmittance efficiency . Yet, metasurfaces whose functionality is based on the excitation of multipolar Mie-type resonances in semiconductor nanoparticles offer many opportunities beyond wavefront control in the passive and linear regime. There are two key features provided by the resonant optical response, which can open up many new functionalities of such metasurfaces. Firstly, the occurrence of resonances leads to strong spatial and spectral dispersion, thereby facilitating tuning of the optical response. Secondly, the resonant enhancement of the electromagnetic near-fields inside or near the nanoresonators allows to enhance and manipulate light-matter interactions, including nonlinear optical processes and spontaneous emission.
This talk will review our recent advances in active tuning, light emission, and nonlinear optical effects in Mie-resonant semiconductor metasurfaces. Two approaches for active tuning of the metasurface response will be discussed, namely integration of the metasurface into a nematic-liquid-crystal cell [3,4] and ultrafast all-optical tuning based on the nonlinear optical response of the constituent semiconductor materials . Furthermore, I will present several strategies to integrate emitters into the metasurfaces and demonstrate that Mie-resonant semiconductor metasurfaces allow for spatial and spectral tailoring of spontaneous emission from various types of emitters. Finally, I will discuss dynamic control of emission from Mie-resonant metasurfaces, which is realized by combining the approaches for active tuning of metasurfaces on the one hand and enhancement of spontaneous emission by metasurfaces on the other hand.
 M. Decker & I. Staude, J. Opt. 18, 103001 (2016).
 K. E. Chong et al., Nano Lett. 15, 5369–5374 (2015).
 J. Sautter et al., ACS Nano 9, 4308–4315 (2015).
 A. Komar et al., Appl. Phys. Lett 110, 071109 (2017).
 M. Shcherbakov et al. Nat. Commun. 8, 17 (2017).
9:00 AM - EM03.01.02
Evolutionary Multi-Objective Optimization of Multi-Resonant Optical Silicon Nanoantennas
Peter Wiecha 1 , Arnaud Arbouet 1 , Christian Girard 1 , Aurelie Lecestre 2 , Guilhem Larrieu 2 , Vincent Paillard 1 Show Abstract
1 , CEMES-CNRS, Toulouse France, 2 , LAAS CNRS, Toulouse France
Photonic nanostructures have attracted increasing attention in the recent past, thanks to the possibility to tailor their optical response to user-defined needs by adapting their size, shape and material. Optical functionalities which can be engineered include scattering and absorption, polarization conversion, optical chirality and non-linear effects. Tailoring of optical properties is usually based on a reference geometry and subsequent variations of this initial design. This approach, however, can be of limited versatility. In particular, it reaches its limits if optimum geometries for very complex optical responses are searched, for example in the search for structures that have multiple simultaneous optical resonances.
To overcome these limitations, we tackle the problem in the inverse way: In a first step we define the target optical response as function of the nanostructure geometry. To determine the optical response of the nanoobject, we use full-field electro-dynamical simulations by the Green Dyadic method. In a second step, we optimize multiple of such objective functions concurrently, using an evolutionary multi-objective optimization algorithm, coupled to the electro-dynamical simulation code. A great advantage of this optimization technique is, that it allows the implicit and automatic consideration of technological limitations like the feasible electron beam lithography resolution.
We demonstrate our multi-objective evolutionary optimization approach by designing double-resonant dielectric nanoparticles. Such high-index dielectric nanostructures are promising low-loss alternatives to plasmonic particles, since the imaginary part of their permittivity is considerably lower . Explicitly, we optimize silicon nanostructures such that they provide two user-defined resonance wavelengths for crossed incident polarizations. Finally, we experimentally verify the predictions of the evolutionary algorithm on nanostructures fabricated using state-of-the-art electron beam lithography .
 Kuznetsov, A. I., Miroshnichenko, A. E., Brongersma, M. L., Kivshar, Y. S. & Luk’yanchuk, B. Optically resonant dielectric nanostructures. Science 354, aag2472 (2016).
 Wiecha, P. R. et al. Evolutionary multi-objective optimization of colour pixels based on dielectric nanoantennas. Nat Nano 12, 163–169 (2017).
9:15 AM - EM03.01.03
Control of Emission and Scattering Properties of Visible Light with Si Nano-Resonators
Ahmet Fatih Cihan 1 , Alberto Curto 1 3 , Soren Raza 1 4 , Aaron Holsteen 1 , Pieter Kik 2 1 , Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States, 3 , Eindhoven University of Technology, Eindhoven Netherlands, 4 , Technical University of Denmark, Lyngby Denmark, 2 , University of Central Florida, Orlando, Florida, United States
Controlling the properties of light, such as directionality and polarization, is a very promising but challenging task with potential applications ranging from nanoscale single-photon sources to macroscale light emission systems. Semiconductor and dielectric resonators have recently emerged as viable candidates for this task thanks to their ability to support multiple resonances in simple structures, lower losses compared to metals and mature fabrication techniques. With these semiconductor antennas, it is possible to excite electric and magnetic resonances and engineer the interaction of these resonances to achieve control over the light emission and scattering processes. In this work, we investigated multiple approaches for controlling such features of visible light. Firstly, we used the dimensions of Si nanowires as the degree of freedom to control the emission directionality of emitted light from dipole emitters. As a result, we demonstrated 25-fold forward-to-backward emission ratio from MoS2. Secondly, with our Si-on-insulator MEMS devices, we utilized the height of similar Si nano-antennas above a mirror to tune and control Mie-type resonances of Si nano-antennas. This MEMS architecture enabled us to have a good control over the nano-antenna to mirror distance with the applied voltage. As a result, we achieved an electrically-, and hence mechanically-, tunable optical resonator platform for controlling multiple features of light emission and scattering in the visible wavelengths.
9:30 AM - EM03.01.04
Magneto-Optical Nanowire Metamaterials
Bo Fan 1 , Mazhar Nasir 2 , Anatoly Zayats 2 , Viktor Podolskiy 1 Show Abstract
1 , University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 , King's College London, London United Kingdom
Magneto-optical (MO) behavior is at the core of polarization-control, telecommunications, sensing, and the emerging field of non-reciprocal photonics. However, homogeneous materials available in nature exhibit relatively weak magneto-optical activity. Plasmonic nanowire metamaterials form a class of composite media that has been shown to enable the enhancement of optical response. In this work, we analyze the optical and opto-magnetic properties of nanowire-based metamaterials comprising of a periodic array of plasmonic nanowires (radius r ∼ 30nm, center-to-center separation a~100nm), with each plasmonic wire surrounded by a thin shell of magneto-optical material (shell thickness h~10nm). Such structures can be fabricated using two-step electrochemical deposition process. In the presence of external static magnetic field, optical response of the MO component of the composite can be described by the permittivity tensor with non-trivial off-diagonal components, resulting in corresponding effective permittivity tensor of the composite. Two directions of the static external magnetic field, (i) parallel to the wires, and (ii) perpendicular to the wires, are considered separately. To calculate the value of effective permittivity tensor, Maxwell- Garnett (MG) formalism was generalized to incorporate magneto-optical response and to deal with potentially large concentration of plasmonic/magneto-optic inclusions. The resulting formalism is further embedded into anisotropic transfer matrix method to calculate optical responses. We demonstrate that the MO shelled plasmonic nanowire exhibits higher off-diagonal permittivity than MO nanowire with same concentration of magneto-optical components. As result, the shelled nanowire media generates stronger Faraday rotation when external magnetic field is applied along the wires. Interestingly, similar to other lossy composites, the MO plasmonic composite yields non-reciprocal transmission in the metamaterial when external static magnetic field is applied along the direction of the optical magnetic field of the plane wave incident on the system. To verify the validity of the developed EMT, transmission, refection and faraday rotation were calculated with fullvectorial 3D commercial finite-element solver. The results of these calculations agree with the predictions of the EMT technique, presented in this work. The developed formalism can be readily used to calculate optical response of a wide variety of nanowire composites that incorporate MO components as well as to design such composites for particular applications.
9:45 AM - EM03.01.05
Metasurface Back Reflectors for External Control over Semiconductor Nanowire Resonances
Jorik Van de Groep 1 , Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States
Semiconductor nanowires (NWs) support strong optical resonances, which enable enhanced interaction with incident light. Their resonant response can be designed at will through engineering of the physical dimensions, semiconductor material, and the dielectric environment. However, patterning the semiconductor material or its direct environment affects surface passivation, which deteriorates the charge carrier collection efficiency of NW devices. Here, we demonstrate how metasurface back reflectors, composed of nanotextured silver interfaces, can be used to obtain control over resonance amplitude and spectrum, without altering the physical shape or dielectric surrounding of the NW.
Positioning a NW above a mirror can give rise to enhanced or suppressed resonant excitation of the NW, determined by the field overlap of the modal field profile and the standing wave pattern of the incident wave. Using deep-subwavelength grooves in the silver back reflector, the excitation efficiency of the NW resonance can be manipulated. Light polarized perpendicular to the grooves couples to plasmonic Metal-Insulator-Metal (MIM) guided modes in the grooves, thereby attaining additional phase pick-up upon reflection. By detailed engineering of the groove width and depth, the spatial profile of the phase pick-up can be controlled with a sub-wavelength resolution.
We employ such locally engineered reflection-phase profiles to demonstrate full control over the optical response of a resonant Si NW positioned above a metasurface back reflector. Changing the groove orientation from perpendicular to parallel to the wire axis prevents light coupling to the MIM mode. A drastic modulation in the resonance absorption efficiency is observed as a result. Alternatively, by applying a gradient in the groove width along the NW the resonance wavelength is tuned from 500-750 nm, corresponding to spectral shift larger than a line width.
To demonstrate this experimentally, we fabricate 20 μm long c-Si NWs (450 nm wide, 50 nm high) on a sapphire substrate using e-beam lithography (EBL) and reactive-ion etching. 100 nm thick Au contacts are used to extract photocurrent from the NW. Next, we apply an 800 nm oxide spacer upon which the silica metamirror pattern (150 nm pitch, 50 nm wide, 35 nm high) is fabricated using EBL. Finally, the pattern is over coated with Ag to complete the back reflector. To characterize the resonant response of the NW, we spatially scan a polarized focussed laser spot over the different metamirror domains along the wire. Using the photocurrent amplitude as a local probe, we demonstrate the ability to control the resonance amplitude and wavelength of the Si NW through accurate engineering of the metamirror pattern. These results demonstrate how metasurfaces enable nanophotonic devices with enhanced functionality.
EM03.02: Ultraviolet Plasmonic Materials
Monday PM, November 27, 2017
Hynes, Level 1, Room 104
10:30 AM - *EM03.02.01
Advances in Active Plasmonic Materials—From UV Photoexcitation to Nanoscale Heat Transfer
Naomi Halas 1 Show Abstract
1 , Rice University, Houston, Texas, United States
Introducing new materials into plasmonics has opened up new opportunities for fundamental advances as well as new applications. For sustainable materials, earth-abundant Aluminum can be formed into nanocrystals with optical properties spanning the visible region of the spectrum, and at small particle size, extending into the UV spectral range. Advances in our understanding of Al nanocrystal growth and surface chemistry facilitate size and shape control in this system. New applications in areas such as photocatalysis and chemical sensing can be realized through these advances. In most plasmonic systems, actuation can be realized by either hot electron-based processes or by photothermal heat-based mechanisms. In photocatalytic materials, both processes can work in concert to facilitate photoreactivity. Photothermal effects still remain an important mechanism for many processes and applications. For example, a new type of membrane distillation process facilitated by direct solar absorption and nanoscale heat transfer can be used for off-grid desalination. New drug delivery nanocomplexes can be shown to respond specifically to photothermal actuation or to photoexcitation by ultrashort laser pulses, resulting in two distinct mechanisms for the delivery of hydrophobic drug molecules in cellular environments.
11:00 AM - EM03.02.02
Local Field Enhancement and Thermoplasmonics in Multimodal Aluminum Structures
Peter Wiecha 1 , Marie Mennemanteuil 2 , Dmitry Khlopin 3 , Jerome Martin 3 , Arnaud Arbouet 1 , Davy Gerard 3 , Alexandre Bouhelier 2 , Jerome Plain 3 , Aurelien Cuche 1 Show Abstract
1 , CEMES - CNRS, Toulouse France, 2 , ICB, University of Bourgogne and CNRS, Dijon France, 3 , LNIO, Institut Charles Delaunay, Troyes France
Aluminum nanostructures have recently been at the focus of numerous studies due to their properties including oxidation stability and surface plasmon resonances covering the ultraviolet and visible spectral windows . These optical properties stems from a plasma frequency situated at a higher energy compared to traditional plasmonic noble metals (Ag, Au). Interestingly, the quest for new plasmonic materials has also been driven by the recent interest in photo-thermal energy conversion by metallic systems.
In this work, we reveal a new facet of this metal relevant for both plasmonics purpose and photo-thermal conversion. The field distribution of high order plasmonic resonances existing in two-dimensional Al structures (200 nm – 2 µm) is studied by nonlinear photoluminescence (nPL) microscopy in a spectral region where electronic interband transitions occur (around 800 nm) . The polarization sensitivity of the field intensity maps shows that the electric field concentration can be addressed and controlled on-demand. We use a numerical tool based on the Green dyadic method to analyze our results and to simulate the absorbed energy that is locally converted into heat. A comparison with similar gold structures demonstrates the higher efficiency of the mechanism in these Al cavities in the red and near infrared part of the electromagnetic spectrum. Finally, the polarization-dependent temperature increase of the Al structures is experimentally measured. The recorded temperature maps are in excellent agreement with theoretical predictions, demonstrating the potential of high order plasmonic resonances in Al .
Our work therefore highlights Aluminum as a promising candidate for designing thermal nanosources, in the visible and near infrared, integrated in coplanar geometries for thermally assisted nanomanipulation or biophysical applications.
 D. Gérard, S. K. Gray, J. Phys. D: Appl. Phys., 48, 184001 (2015).
 J. Martin, M. Kociak, Z. Mahfoud, J. Proust, D. Gérard, and J. Plain, NanoLett., 14, 5517-5523 (2014).
 A. Cuche, M.-M Mennemanteuil, D. Khlopin, J. Martin, A. Arbouet, D. Gérard, A. Bouhelier, J. Plain and A. Cuche, submitted (2017).
11:15 AM - EM03.02.03
Emission Pattern of Deep-Blue Semiconducting Polymer Emitter Thin Films with Different Emission Dipole Orientations Modified by UV-Plasmonic Structures
Zeqing Shen 1 , Maria Adrover 1 , Yutong Wu 1 , Katsuya Noji 1 , Deirdre O'Carroll 1 Show Abstract
1 , Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States
Semiconducting polymers are versatile optoelectronic materials that are beginning to displace more traditional semiconductors for thin-film lighting and display applications. However, the low light extraction efficiency for semiconducting-polymer-based thin-film planar devices limits the overall device performance. Around 80% of emission is trapped to photonic waveguide modes or to surface plasmon polariton (SPPs) at the metallic electrode surface. Use of nanostructured electrodes has proved to improve the light extraction efficiency of organic thin-film light-emitting devices. However, because of the variety of possible polymer chain orientations in thin films, a comprehensive understanding of the influence of polymer chain alignment on the enhancement mechanisms is needed to design device structures for better light extraction from a certain polymer.
In this study, thin-films of two deep-blue emitting semiconducting polymers with different emission dipole orientations are used to study the influence of random nanohole metal (Ag, Al, Mg) thin films (NHM) on their emission patterns. Poly(9,9-dioctylfluorene) (PFO) exhibits emission dipoles that are predominately oriented in-plane, while poly[N-(1-octylnonyl)-9H-carbazole-2,7-diyl] (PCzON) is believed to have both in-plane and out-of-plane emission dipoles. Despite their different dipole orientations, the emission spectra of both polymers are almost identical (exhibit max emission intensity ~430 nm). Finite-difference time-domain (FDTD) simulation is applied to investigate the influences of film thickness and nanohole diameter on the hole resonances wavelengths. The NHM are fabricated using a colloidal lithography method, in which polystyrene (PS) beads with different diameters are spin coated onto glass substrates using different spin speeds before metal thin films thermal evaporation and PS beads lift-off to vary the nanohole size and density. Our preliminary large-area angle-resolved photoluminescence study indicates that 50 nm thick nanohole Ag (NHAg) with a hole diameter of 200 nm (exhibits strongly enhanced local electrical filed between 340-400 nm at the pore edge based on simulation) and a hole density of 0.226 /μm2 could enhance the emission intensity of PFO thin films at emission angles between 20o to 60o off-normal by up to 25% (at 20o), and enhance the emission intensity of PCzON thin film at emission angles between 20o to 60o off-normal by up to 100% (at all angles). Fourier plane imaging and 3-dimentional electromagnetic simulations will be applied to understand the origin of local far-field emission pattern modification by a single hole.
11:30 AM - EM03.02.04
Spectrally Broad Plasmonic Absorption in Core-Shell Ga and In Nanoparticle Hybrids
Nuria Gordillo 1 , Andres Redondo-Cubero 1 , Sergio Catalán-Gómez 1 , Javier Palomares 2 , Luis Vázquez 2 , Jose Luis Pau 1 Show Abstract
1 Departamento de Física Aplicada, Universidad Autónoma Madrid, Madrid Spain, 2 Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Científicas, Madrid Spain
Gallium and indium nanoparticles (NPs) have attracted a lot of interest in the last years for biosensing and photonic devices [1,2], since they provide a wide tunability of the plasmon resonance energy, from the UV to the IR spectral region. This resonance is controlled by the size, shape, interdistance and the refractive index of the surrounding media . Interestingly, these NPs develop a native thin oxide on the surface that preserves the metal from the environment . Furthermore, by thermal processes the thickness of the oxide layer can be increased, tuning the core-shell architecture and modifying the plasmon resonance with the annealing time and temperature .
In this work we use Joule-effect thermal evaporation to produce Ga and In NPs on silicon (100) substrates. The coalescence processes during the growth determine the average size of the NPs and the energy position of the plasmonic resonance. Taking advantage of the resistant oxide shell, Ga and In NPs can be used as a template for a second deposition step without structural changes, enabling the hybridation of NPs of different materials. Thus, we fabricate a complex cluster of mixed NPs which presents a spectrally broad plasmonic absorption that can be optically coupled with a wide range of photon energies. We characterize the surface morphology by means of scanning electron and atomic force microscopy. The local surface plasmon resonance was determined by spectroscopic ellipsometry and compared with discrete dipole approximation simulations. These results explore the benefits and limits of hybridation, in new platforms for optical sensing devices.
1. A. García Marín et al., Biosens. Bioelectron. 74, 1069 (2015)
2. Y. Kumamoto et al., ACS Photonics 1, 598 (2014).
3. K.A. Willets et al., Annu. Rev. Phys. Chem. 58, 267 (2007)
4. S. Catalán-Gómez et al., Nanotech., submitted (2017)
11:45 AM - EM03.02.05
Formation and Optical Properties of Indium Nanoparticles for Deep-UV Plasmonics
Ethan Lu 1 , Julia Trombley 1 , Robert Polski 1 , Christian Greenhill 1 , Davide Del Gaudio 1 , Caleb Reese 1 , Rachel Goldman 1 Show Abstract
1 Materials Science and Engineering, University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States
Metal nanoparticle (NP) arrays often exhibit collective electron oscillations (plasmon resonances) which are promising for enhanced light emission, efficient solar energy harvesting, ultra-sensitive biosensing, and optical cloaking. To date, materials research and device fabrication have focused nearly exclusively on silver and gold NP dispersions in two dimensions (2D); these arrays exhibit localized surface plasmon resonances (LSPRs) limited to visible wavelengths. Alternatively, indium has the potential to be a low-loss, high gain plasmonic material with LSPRs tunable to the deep-UV range1. Here, we use a combined computation-experimental approach to examine the formation and plasmonic properties of indium NPs on silicon substrates.
Using Lumerical finite-difference time-domain (FDTD) simulations, we examine the influences of indium NP and NP array sizes on the absorptive behavior of silicon. We compute the LSPR energy values and corresponding absorption efficiencies (effective absorption cross-section of droplet / geometrical cross-section of droplet), observing a linear redshift in LSPR energies (from 7.0 to 5.5 eV) as the average NP radii increases from 10 to 50 nm. With increasing array size, the maximum absorption efficiency stabilizes at 2.5, a ratio comparable to that of gold2. For sizable arrays, this peak occurs at LSPR energies from 5.5 to 6.5 eV, depending on indium NP radii, suggesting the potential of LSPR energies tunable to the deep-UV region.
To fabricate NP arrays, we use molecular-beam epitaxy to deposit 3, 4, 5, 6.5, and 8 equivalent monolayers (MLs) on silicon substrates. An analysis of atomic force micrographs of the NP arrays reveals mean diameters ranging from 12 to 60 nm. Furthermore, 2D radial pair correlation analysis indicates significant short-range clustering for the longer depositions (6.5, 8 ML). To determine the imaginary component of the dielectric constant of the NP array, we have performed ellipsometry measurements, and we observe multiple LSPR energies up to 4.3 eV, well within the deep-UV region. We will discuss the influences of possible NP oxidation on the discrepancies between the measured and computed LSPR energy values for indium NPs on silicon.
We gratefully acknowledge support from the National Science Foundation (Grant No. DMR-1120923) through the Materials Research Science and Engineering Center (MRSEC) at the University of Michigan.
 J.M. McMahon, G.C. Schatz, and S.K. Gray, Phys. Chem. Chem. Phys. 15, 5415 (2013).
 P.K. Jain, K.S. Lee, I.H. El-Sayed, and M.A. El-Sayed, J. Phys. Chem. B 110, 7238 (2006).
EM03.03: Graphene and Carbon Nanotubes
Monday PM, November 27, 2017
Hynes, Level 1, Room 104
1:30 PM - *EM03.03.01
Plasmons at the Atomic Scale
Javier Garcia de Abajo 1 Show Abstract
1 , ICFO, Castelldefels Spain
Plasmons -collective oscillations of electrons in conducting materials- have provided the tools to engineer artificial structures capable of manipulating light over wide spectral and spatial ranges. The emergence of exfoliated 2D materials as excellent plasmonic systems has opened new possibilities to explore optical phenomena at atomic scales and their applications in light modulation, sensing, and spectral photometry, as well as in nonlinear and quantum optics. In this talk, we will review recent advances in the fields of graphene and 2D material plasmonics, including examples of the applications mentioned above and extensions toward similar phenomena in small molecules. Special emphasis will be placed on ultrafast phenomena and the opportunities opened by the extraordinary nonlinear and quantum properties of these materials.
2:00 PM - EM03.03.02
Self-Assembly of Graphene-Based Nanotubes for Plasmonic Applications
Chunhui Dai 1 , Kriti Agarwal 1 , Daeha Joung 1 , Jeong-Hyun Cho 1 Show Abstract
1 , University of Minnesota, Minneapolis, Minnesota, United States
Plasmons induced in graphene have attracted great attention due to the advanced optical properties exhibited such as frequency tunability, long plasmon lifetime, and strong light confinement. Using these optical properties, diverse applications have been heavily investigated in recent years. However, restricted graphene patterns (nanoribbons or discs) defined on planar substrates limit the possibility for further exploration of the advantages of graphene. Here, we develop a new nanofabrication process to realize a 3D graphene nanostructure, forming graphene tubes with a diameter of 500 nm, by using plasma that triggers grain coalescence of a Sn sacrificial layer in a reactive ion etching (RIE) system. By tuning the conditions of the plasma, freestanding open or closed nano tubes can be fabricated for different purposes. In addition, nanotubes with a high aspect ratio of 1000 (length = 500,000 nm/diameter = 500 nm) have been realized. Through modeling analysis with COMSOL simulation software, a novel optical property, extremely strong volumetric near-field enhancement, can be observed in the graphene tube. This property shows the possibility for applying the mechanism for highly sensitive non-contact detection that maintains their integrity because of the impermeability of the graphene membranes.
2:15 PM - EM03.03.03
Plasmonics of Uniform, Aligned Carbon Nanotube Arrays
Po-Hsun Ho 1 , Damon Farmer 1 , Abram Falk 1 , Kuan-Chang Chiu 1 , George Tulevski 1 , Phaedon Avouris 1 , Shu-Jen Han 1 Show Abstract
1 , IBM T.J. Watson Research Center, Yorktown Heights, New York, United States
Carbon nanotubes provide a rare access point into the plasmon physics of one-dimensional electronic systems that operate as terahertz and infrared antennas at deep subwavelength scales. By assembling purified nanotubes into uniformly sized arrays, we show that they support coherent plasmon resonances, that these plasmons couple to nanotube and substrate phonons, and that the resulting phonon-plasmon resonances have quality factors as high as 10. The problem of limited absorption provided by these thin film arrays is addressed by assembling much thicker films of aligned and uniformly-sized carbon nanotubes, and showing that their plasmon resonances are strong, narrow, and broadly tunable. These thick arrays exhibit peak attenuation reaching 70% with resonator quality factors approaching that of their thinner counterparts. These resonators are strongly blue-shifted with increasing film thickness, allowing resonant wavelengths as small at 1.4 μm to be attained, well within the technologically important infrared telecom band. This material platform is a promising candidate for infrared photodetectors, nanoscale lasers, and chemical sensors based on surface-enhanced infrared absorption.
2:30 PM - EM03.03.04
Self-Assembled Tin Nanodots Induced Broadband Light Trapping in Single Layer Graphene
Sidan Fu 1 , Xiaoxin Wang 1 , Haozhe Wang 2 , Jing Kong 2 , Jifeng Liu 1 Show Abstract
1 Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, United States, 2 Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Graphene is a representative of two dimensional materials with promising electrical and optical properties for infrared photonic devices. However, single layer graphene (SLG) by itself suffers from limited optical absorption (2.3%) , which significantly limits its efficiency as photonic and optoelectronic devices. Here, a novel technique is introduced to address this challenge by coating the graphene with self-assembled Sn nanodots for highly effective infrared light scattering and trapping in SLG, due to the significantly high imaginary part and nearly zero real part of refractive index of Sn at such wavelengths . The Sn nanodots-coated SLG shows clear contrast to the region on the same sample without SLG, i.e. the color is much darker due to strongly enhanced optical absorption of up to 15% over a broadband wavelength range from 500nm to 8000nm. Meanwhile, the straightforward fabrication process of Sn nanodots, specifically the thermal evaporation, maintains the perfectness of the SLG lattice, a great advantage compared to the sputtering process  for fabricating photon management structures. Such a contrast is contributed by two factors based on the experimental and theoretical analyses: (1) the enhanced absorption of SLG, in which near field electromagnetic interaction at the interface of Sn nanodots and SLG plays a dominant role; (2) the morphological variation of Sn nanodots on SLG vs. on different substrates. It’s found out the optical behavior is related to the geometry and the size of nanodots, as well as the gap between them. Theoretical modeling successfully matches the optical transmittance/reflectance/absorption spectrum of a representative sample with over 10% enhanced absorption of SLG in visible and infrared light range. The optical absorption enhancement results have also been confirmed by photocurrent measurement both with an infrared laser (λ=1550nm) and a red laser (λ=650nm). Further coupled with dielectric/metal photonic cavity structures, >40% optical absorption in SLG (i.e. >20x absorption enhancement) can be achieved in a broad spectral regime at λ > 1500 nm for IR photonic devices. Such a facile and highly effective light trapping technique would be a great improvement for the development of graphene based photonics and optoelectronics.
 R. R. Nair, P. Blake, and A. N. Grigorenko, et al, Science 320, 1308 (2008)
 K. Takeuchi and S. Adachi, Journal of Applied Physics 105, 073520 (2009)
 R. Beams, L. G. Cancado, and L. Novotny, Journal of Physics: Condensed Matter, 27, 083002, (2015)
2:45 PM - EM03.03.05
Terahertz Band Communication Using Plasma Wave Propagation in Multilayer Graphene Heterostructures
Shaloo Rakheja 1 Show Abstract
1 , New York University, Brooklyn, New York, United States
Graphene, which is an atomically thin sheet of carbon atoms arranged in a honeycomb lattice, displays strong light-matter interaction over a broad frequency range. Graphene can be easily combined with other two-dimensional (2D) materials, such as transition metal dichalcogenides, phosphorene, and hexagonal boron nitride, to develop a fully integrated solution for the generation, detection, modulation, and propagation of plasma waves, also called surface plasmons (SPs) [1-2].
In this work, we demonstrate the applications of SPs for on-chip and off-chip wireless signaling purposes in the terahertz (THz) band. For on-chip communication, we examine the propagation characteristics of THz SPs in single-waveguide (SWG) and parallel-plate waveguide (PPWG) interconnects utilizing multilayer (ML) graphene as the guiding medium. The tunability of SPs by applying a gate voltage in the PPWG interconnect is examined and proposed as a solution for building reconfigurable 2D plasmonic devices . In the case of off-chip wireless communication, we quantify the requirements of graphene nano-antennas in terms of their resonant length, compression factor, and radiation rate. The SP dispersion characteristics are derived by solving Maxwell’s equations in the device setup in which graphene presents an impedance boundary condition. The effect of number of layers, electrostatic screening, and Fermi level are included in the model of intra-band dynamical surface conductivity of ML graphene, which is derived using the Kubo formalism. The electrical generation and detection of SPs in graphene field-effect transistor (FET) is modeled using the hydrodynamic theory of the Dyakonov-Shur (DS) mechanism . We discuss the plasma-wave instability that occurs in the graphene FET channel when the device is subject to a dc current bias. Limits on the channel length to sustain undamped or weekly damped plasma waves are derived.
We develop models for energy-per-bit and bandwidth density of graphene-based SWG and PPWG interconnects. The energy-per-bit calculation includes the energy consumed in the excitation and detection circuitry as well as in the modulator for converting electrical energy into optical energy. The analysis is conducted within a noise-limited transmission model of SP propagation. Both thermal noise and shot noise effects are considered to evaluate the minimum number of plasmons needed for correct detection given the modulation depth and the bit-error requirement of the system. We also quantify optimal interconnect length scales for which plasmonic interconnects outperform conventional copper/low-k electrical interconnects in next-generation systems.
 F. Xia et al., Nature Nanotechnology, 4(12):839–843, 12 2009.
 M. Jablan et al., Physical review B, 80(24):245435, 2009.
 S. Rakheja and P. Sengupta, IEEE Transactions on Nanotechnology, 15(1): 113–121, 2016.
 V. Ryzhii et al., Journal of Applied Physics, 101(2): 024509, 2007.
EM03.04: Plasmonic Lasers
Monday PM, November 27, 2017
Hynes, Level 1, Room 104
3:30 PM - *EM03.04.01
Advances in Plasmonic Quatum Dot Lasers
Yasuhiko Arakawa 1 Show Abstract
1 , The Univ of Tokyo, Tokyo Japan
Since the first proposal of the concept of the quantum dot in 1982 , the quantum dots have been intensively studied for both fundamental solid state physics and advanced device applications. Full discretization of the energy levels of electrons in quantum dots has enabled to realize high performance quantum lasers and quantum information devices such as single photon sources. One of the targets of the future quantum dot nanophotonic devices is ultra-small size lasers (i.e., nanolasers).
As conventional quantum dot lasers have been limited to photonic cavities that are diffraction-limited, further miniaturization to meet the demands of nanophotonic-electronic integration applications is challenging issues. Here we introduce a quantum dot-based plasmonic laser to reduce the cross-sectional area of nanowire quantum dot lasers below the cutoff limit of photonic modes while maintaining the length in the order of the lasing wavelength. Metal organic chemical vapor deposition grown GaAs–AlGaAs core–shell nanowires containing InGaAs quantum dot stacks are placed directly on a silver film, and lasing was observed from single nanowires originating from the InGaAs quantum dot emission into the low-loss higher order plasmonic mode. Lasing threshold pump fluences as low as ∼120 μJ/cm2was observed at 7 K, and lasing was observed up to 125 K. Temperature stability from the quantum dot gain, leading to a high characteristic temperature was demonstrated. A plasmonic laser with the quantum dot gain in a micro-disc resonator will be also discussed.
Reference  Y. Arakawa, H. Sasaki, Appl. Phys. Lett. 40, 939 (1982)  J. Tatebayashi, S. Kako, J. Ho, Y. Ota, S. Iwamoto, Y. Arakawa, Nat.
Photonics 9, 50110 (2015)  J. Ho, J. Tatebayashi, S. Sergent, C. Fai Fong, Y. Ota, S. Iwamoto, Y. Arakawa, Nano Lett.16 2845-2850 (2016)
4:00 PM - EM03.04.02
Pump-Profile Engineering for Spatial- and Spectral-Mode Control in Two-Dimensional Colloidal-Quantum-Dot Spasers
Robert Keitel 1 , Jian Cui 1 , Stephan Kress 1 , Boris le Feber 1 , Ario Cocina 1 , Karl-Augustin Zaininger 1 , David Norris 1 Show Abstract
1 , ETH Zurich, Zurich Switzerland
In the initial proposal of the spaser – a source of coherent, intense, and narrow-band surface plasmons – colloidal quantum dots were envisioned as an ideal gain medium for compensation of the significant losses intrinsic to plasmonics. However, many spasers shown to date have required a single material to both serve as a gain medium and define the plasmonic cavity, a design that prevents the use of quantum dots or other colloidal nanomaterials. In addition, these concepts are inherently challenging for integration in a larger plasmonic circuit.
We have recently established a new class of spasers in which the gain medium and cavity are decoupled by combining both top-down and bottom-up fabrication. Our devices consist of planar plasmonic Fabry-Perot-type cavities, defined by aberration-corrected block reflectors placed precisely on an ultrasmooth silver substrate, that are then filled with colloidal quantum dots. Photoexcitation yields high-quality-factor (Q~1000) multimode spasing within the gain envelope of the quantum-dot emission spectrum.
In contrast to many conventional laser sources, our cavity design allows direct access to the full active region due to its two-dimensional nature. Consequently, the device can be pumped not only in its entirety with a spatially uniform beam, but with arbitrary 2D pump profiles generated by a spatial light modulator. In combination with the extremely high quality factors, this gives us unprecedented access to the physics of spaser modes. Using well-defined excitation patterns, we are thus able to isolate the contributions of specific modes, both transverse and longitudinal.
With analytical calculations of the spasing modes based on gaussian beam analysis as a starting point for well-defined excitation patterns, we are able to bias the mode competition adaptively in favor of specified transverse modes. We thereby experimentally verify the applicability of conventional laser theory to spasers. Furthermore, we are able to draw conclusions on the validity of the use of parabolic mirrors to match the wavefront of Hermite-Gaussian modes for a range of different cavity aspect ratios. Our technique of spatially modulated pumping allows efficient characterization of 2D spasers and thus paves the way towards engineering of devices with optimized device footprint for on-chip applications.
4:15 PM - EM03.04.03
Band-Edge Engineering for Controlled Multi-Modal Nanolasing in Plasmonic Superlattices
Danqing Wang 1 , Ankun Yang 1 , Weijia Wang 1 , Yi Hua 1 , Richard Schaller 1 2 , George Schatz 1 , Teri Odom 1 Show Abstract
1 , Northwestern University, Evanston, Illinois, United States, 2 , Argonne National Laboratory, Lemont, Illinois, United States
Miniaturized lasers enable applications in on-chip optical communication, medical imaging, and nanoscale optical displays. Compared to traditional lasers, plasmonic nanolasers can break the diffraction limit and support ultrasmall mode volumes, but unwanted multi-modal nanolasing exhibits both uncontrolled mode spacing and output behavior. Single band-edge states can trap slow light and function as high-quality optical feedback from for microscale lasers to nanolasers. However, access to more than a single band-edge mode for nanolasing has not been possible because of limited cavity designs.
This presentation will focus on plasmonic superlattices—finite-arrays of nanoparticles grouped into microscale arrays—to support multiple band-edge modes capable of multi-modal nanolasing at programmed emission wavelengths and with large mode spacings. Moreover, tuning NP size can provide an additional degree of freedom for manipulating the output behavior of different lasing modes. Modeling the superlattice nanolasers with a four-level gain system and a time-domain approach revealed that the accumulation of population inversion at plasmonic hot spots can be spatially modulated by the diffractive coupling order of the patches. Also, symmetry-broken superlattices exhibited switchable nanolasing between a single mode and multiple modes. Coherent nanoscale light sources with multiple tunable, on-demand optical modes can enable multiplexing for on-chip photonic devices and offer prospects for multi-modal laser designs.
4:30 PM - EM03.04.04
Surface-Plasmon-Polariton Laser Based on a Metallic Trench Fabry-Perot Resonator
Wenqi Zhu 1 3 , Cheng Zhang 1 3 , Ting Xu 3 , Haozhu Wang 2 , Parag Deotare 2 , Amit Agrawal 1 3 , Henri Lezec 1 Show Abstract
1 , National Institute of Standards and Technology, Gaithersburg, Maryland, United States, 3 , University of Maryland, College Park, Maryland, United States, 2 , University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States
Recently, metal based resonators sustaining surface plasmons have emerged as a promising route to achieve lasing at nanometer-scale dimensions. However, optimizing the absorption efficiency of free-space pump beams by the gain media used in plasmon amplifiers and lasers, without simultaneously introducing significant loss channels for the amplified/lasing modes, remains an important and challenging problem. Here, we show room-temperature lasing of propagating surface plasmon polaritons (SPPs) confined to an metallic trench Fabry-Perot cavity having ultra-narrow linewidth at visible frequency. We further show how the lasing threshold can be substantially lowered by efficiently coupling the excitation beam into a pump SPP using a grating directly located within the cavity and having profile and orientation designed to minimally perturb the lasing SPP.
The proposed SPP-pumped SPP-laser is fabricated using a modified template-stripping process in which the Si mesa is patterned to simultaneously mold the Fabry-Perot cavity and the tapered coupling grating on the cavity floor. The gain medium consists of a host medium of PMMA doped with DCM laser dye to a concentration of 3 mM with a thickness of ≈ 260 nm on the cavity floor. To achieve efficient absorption of pump light, we leverage a low-profile, sinusoidal grating added onto the cavity floor to convert the free-space pump beam into SPP standing waves confined to the cavity floor (“pump SPPs”), resulting in orthogonal standing waves for lasing SPPs and pump SPPs, respectively. In addition, the grating height is modulated to yield a gently tapered profile towards each side of the cavity.The evolution of the emission spectra measured from the resulting device as a function of increasing pump power displays linewidth-narrowing and a distinct emission threshold, suggesting lasing action of the SPPs at the wavelength λE ≈ 617 nm. Specifically, the emission linewidth reaches a minimum value Δ = (0.24 ± 0.14) nm, when the pump beam is polarized parallel to the sidewalls (along the y-direction) and its intensity is above the threshold value Ith = (5.6 ± 1.2) MW/cm2. The record narrow lasing linewidth achieved here is substantially narrower than that of localized–plasmon lasers and comparable to that of the best semiconductor based gap–plasmon laser demonstrated to date.
In summary, we achieved a low-threshold, narrow-linewidth SPP laser that simultaneously supports low-loss resonances for the lasing SPPs and enhanced absorption through the excitation of pump SPPs. The trench configuration leveraged here intrinsically allows for efficient interaction between an analyte and the evanescent tail of the narrow-linewidth SPP lasing mode extending into the open space above the gain medium, leading to the possibility of active, high-contrast refractive index sensing and surface-analyte detection.
4:45 PM - EM03.04.05
Suppressing Non-Radiative Surface Plasmon Loss in Metalic Electrodes
Majid Esfandyarpour 1 , Alberto Curto 1 , Pieter Kik 2 , Nader Engheta 3 , Mark Brongersma 1 Show Abstract
1 Material Science and Engineering, Stanford University, Stanford, California, United States, 2 CREOL, University of Central Florida, Orlando, Florida, United States, 3 Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
High-performance light-emitting diodes (LEDs) rely on high sheet-conductivity metallic contacts to facilitate effective charge injection. Unfortunately, such contacts also support surface plasmon polariton (SPP) excitations that guide and ultimately dissipate optical energy in the metal. The coupling of quantum emitters to SPPs constitutes one of the key loss processes that limit the external quantum efficiencies of LEDs and in state-of-the-art organic LEDs roughly 40% of the power is lost in this fashion.
Here, inspired by the concept of radio-frequency (RF) high-impedance surfaces and their use in conformal antennas we illustrate how electrodes can be nanopatterned to simultaneously provide a high DC electrical conductivity and high-impedance at optical frequencies. Such electrodes do not support SPPs across the visible spectrum and greatly suppress dissipative losses while facilitating a desirable Lambertian emission profile. We verify this concept by studying the emission enhancement and photoluminescence lifetime for a dye emitter layer deposited on the electrodes.
Stephanie Law, University of Delaware
Viktoriia Babicheva, ITMO University
Svetlana Boriskina, Massachusetts Institute of Technology
Frank Neubrech, University of Heidelberg
EM03.05: Tunable Metamaterials and Metasurfaces
Tuesday AM, November 28, 2017
Hynes, Level 1, Room 104
8:00 AM - *EM03.05.01
Optoelectronic Device Applications of Metafilms
Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States
Many conventional optoelectronic devices consist of thin, stacked films of metals and semiconductors. In this presentation, I will demonstrate how one can improve the performance of such devices by nano-structuring the constituent layers at length scales below the wavelength of light. The resulting metafilms and metasurfaces offer opportunities to dramatically modify the optical transmission, absorption, reflection, and refraction properties of device layers. This is accomplished by encoding the optical response of nanoscale resonant building blocks into the effective properties of the films and surfaces. To illustrate these points, I will show how nanopatterned metal and semiconductor layers may be used to enhance the performance of active metafilm devices.
8:30 AM - EM03.05.02
Giant Interband Transitions—Towards Switchable Plasmonics and Low-Loss Nanophotonics on a Single-Material Platform
Johann Toudert 1 2 , Rosalia Serna 1 Show Abstract
1 Laser processing Group, Instituto de Optica, IO-CSIC, Madrid Spain, 2 , ICFO, Castelldefels, Barcelona, Spain
During the last years, the fields of plasmonics and nanophotonics have been strengthened by the identification of alternative plasmonic materials better suited than gold and silver for specific applications, and by the demonstration of low-loss Mie resonances in subwavelength dielectric nanostructures. These findings have stimulated the development of a rich variety of new material architectures, appealing for plasmonic applications at high temperatures and beyond the visible, and for low-loss nanophotonics.
Currently, in the fields of plasmonics and nanophotonics two main challenges concerning the material platforms can be identifie: first the need to achieve materials with a reversibly tunable dielectric function for the development of switchable plasmonic devices, and second the need to achieve dielectrics with a very high refractive index in order to enable low-loss nanophotonics compete with plasmonics in terms of miniaturization. For the first case plasmonic materials, where the driving mechanism is the excitation of free charge carriers, are not reversibly tunable. For the second case, Silicon, the most used platform for low-loss Mie resonances, has a refractive index of 4 that sets the minimum size of visible-near infrared resonators at more than 100 nm.
However there is a kind of materials that can address both challenges. Recently, there have been demonstrations of ultraviolet-visible plasmon resonances without need of free charge carrier excitation in semi-metals and topological insulators,1,2 and of low-loss Mie resonances in subwavelength nanostructures of lead telluride, semiconductor with a refractive index of 6.3 We will demonstrate that the optical properties of these materials, which all consist of elements of the p-block of the periodic table, are driven by giant interband transitions. These interband transitions make the material behave optically as a metal (negative dielectric permittivity) at their high energy side, and as a high refractive index dielectric at their low energy side. The magnitudes of the negative permittivity and high refractive index depend on the strength of the interband transitions. In this context, we will evaluate the potential of a broad range of elements and compounds of the p-block for plasmonics and low-loss nanophotonics.4 We will make a special emphasis on bismuth that presents the strongest interband transitions reported so far,5 which enable its plasmonic behavior in the ultraviolet-visible and yield an infrared refractive index close to 10. Finally, we will report the tunability of its dielectric function in relation with plasmonics and nanophotonics both in the ultraviolet-visible and infrared regions.
1. J. Yin, H. N. S. Krishnamoorthy, G. Adamo, et al., arXiv:1702.00302 [ physics.optics]
2. J. Toudert, and R. Serna, Opt. Mat. Expr. 7, 2434 (2016).
3. T. Lewi, H. A. Evans, N. A. Butakov, J. A. Schuller, NanoLett. 17, 3940 (2017).
4. J. Toudert, and R. Serna, Opt. Mater. Express 7, 2299 (2017).
5. J. Toudert, R. Serna, I. Camps, J. Wojcik, P. Mascher, E. Rebollar, T. Ezquerra, J. Phys. Chem. C 121, 3511 ( 2017).
8:45 AM - EM03.05.03
Creating a Dynamically Tunable Si/Au Metamaterial Polarizing Filter
Nicole Pfiester 1 , Emily Carlson 1 , Dante Demeo 1 , Corey Shemelya 2 , Thomas Vandervelde 1 Show Abstract
1 , Tufts University, Medford, Massachusetts, United States, 2 , Technische Universität Kaiserslautern, Kaiserslautern Germany
Present polarimetry techniques require a different filter for each polarization of light you wish to measure. This often requires a cluster of four pixels to differentiate between the polarizations incident on an area, reducing the final image resolution compared to a non-polarized image, or a large mechanical filter wheel. Metamaterials can be leveraged to design materials with a polarization sensitive response. Dynamic tuning of this response, or adjusting the metamaterial behavior post-fabrication, can be used to create a filter that can be turned on and off for a given polarization. An integrated stack of these filters would allow the measurement of any polarization direction at the full resolution capacity of the detector. To achieve this, we have explored the use of a bias voltage to tune the optical response of a silicon and gold metamaterial.
We designed a metamaterial structure that generates a polarization-dependent response in the mid-infrared wavelength range. Off-setting the absorption and transmission peaks for the two polarizations allows equal transmission while the filter is in a static state, or without a bias voltage. The application of a bias changes the metamaterial response and blocks polarized waves parallel to one axis. A thin film semiconductor layer is required to achieve this effect. Previous work utilized thin film gallium arsenide, but poor film quality of the epitaxial layer, with surface roughness on the order of the metamaterial feature size, did not provide sufficient conductivity for an applied bias to impact the light interactions. We will present new results using thin film silicon with a gold nanostructure pattern. A static filter, one that does not require an applied voltage to operate as a polarizing filter, was fabricated to demonstrate the design suitability. We will report on our progress toward a dynamic filter and compare to previous results with III-V films.
9:00 AM - EM03.05.04
Dynamic Beam Steering Using Coherent Control of Frequency-Arrayed Light in Metasurfaces
Amr Shaltout 1 , Konstantinos Lagoudakis 1 , Jorik Van de Groep 1 , Soo Jin Kim 1 , Jelena Vuckovic 1 , Vladimir Shalaev 2 , Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States, 2 , Purdue University, West Lafayette, Indiana, United States
The state-of-the-art laser beam steering devices are implemented using phased-array optical technology which utilizes liquid crystals, Lithium Niobate cells or other means of electro-optic spatial light modulators. This technology generates laser beams that can scan a large angle of view within a time scale in the order of microseconds. Reducing the steering time is beneficial with the advent of new real-time applications such as autonomous vehicles for the sake of higher frame rate as well as improved resolution. In order to further reduce the steering time to nanosecond or picosecond scale, we developed a novel methodology using spatiotemporal coherent control of frequency-arrayed light. This technique has been designated in analogy with coherent control of quantum dynamics where the time evolution of the quantum-mechanical wave is controlled through coherent superposition of multi-energy eigen-states. Similarly, optical waves with multi-frequencies can be coherently controlled to reorient the laser beam with time and built a beam steering device.
The spatiotemporal coherent control method is implemented through silicon-based metasurface alongside a mode-locked laser with a frequency-comb spectrum (i.e., an equally spaced phased-locked frequency lines). The metasurface is thoughtfully designed to engineer different spatial distribution of optical waves in the far-field for different spectral lines of the frequency-comb. This arrangement creates a coherently controlled spatiotemporal optical patterns, where multi-frequency optical modes coherently interfere to propagate in a specific direction, and this direction changes with time providing the sought after beam steering device. Because the steering of the laser beam does not require external modulation like phased-array technology, the steering action can go significantly faster.
We experimentally achieved laser scanning over a 400 angle during a time interval in the order of 10 pico-seconds. This is five orders of magnitude enhancement in scanning speed over the state-of-art phased-array technology. In addition, this technology can broaden the scope of flat photonics towards spatiotemporal engineering of other optical patterns to build more devices such as ultrafast axial scanners or dynamic holograms. Furthermore, the novel methodology of coherently controlled frequency-arrayed beam steering is not limited to optical devices. It can be extrapolated to other fields including acoustic/sonar imaging and wireless telecommunications technology.
9:15 AM - EM03.05.05
Active Control of Chiroptical Surfaces and Transparent Solar Radiators with Bottom-Up Magnetoplasmonics
Alexandre Dmitriev 1 Show Abstract
1 Department of Physics, University of Gothenburg, Gothenburg Sweden
A major challenge facing the plasmon-based nanophotonics is the poor dynamic tunability. A functional adaptive nanophotonic element would feature the real-time large tunability of transmission, reflection of light intensity and/or polarization over a broad range of wavelengths, and would be robust and easy to integrate. Several approaches have been explored so far including mechanical deformation [1-3], thermal  or refractive index [5, 6] effects, and all-optical switching [7, 8]. Building on our previous advances of the combination of the plasmonic and ferromagnetic materials (magnetoplasmonics) [9-13], here we devise an ultra-thin chiroptical surface, built on 2D nanoantennas, where the chiral light transmission is controlled by the externally applied magnetic field. The magnetic- field induced modulation of the far-field chiroptical response with this system exceeds 100% in the visible and near-infrared spectral ranges, opening the route for nanometer-thin magnetoplasmonic light-modulating surfaces tuned in real time and featuring a broad spectral response.
Architectural windows are a major cause of thermal discomfort of building inhabitants as the inner glazing during cold days can be several degrees colder than the ambient air. Often these effects are mitigated by increased indoor temperature leading to greater thermal losses. Using ferromagnetic materials as effective thermal radiators , we present solar thermal surfaces based on complex nano-plasmonic antennas that can raise the temperature of glazing by 8°C upon solar irradiation while transmitting light with a color rendering index, Ra, of 98,76 (Standard illuminant-D, 7339 K). The structural integrity of these antennas is not substrate dependent and thus they open up for application on a broad range of transparent surfaces.
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 V. Bonanni et al., Nano Lett. 11, 5333 (2011).
 G. Edman Jonsson et al., Sci. Rep. 4:5111, doi: 10.1038/Srep05111 (2014).
9:30 AM - EM03.05.06
Millivolt-Scale Modulation of Optical Response of Plasmonic Heterostructures via Bias-Induced Ionic Transport
Krishnan Thyagarajan 1 , Ruzan Sokhoyan 1 , Leonardo Zornberg 1 , Harry Atwater 1 Show Abstract
1 , California Institute of Technology, Pasadena, California, United States
Ionic conductance has been widely-explored as a mechanism for resistive switching in electrochemical random access memory (RRAM) devices , and more recently, also for demonstration of optical modulation in nanophotonic devices bias . Here, we report an unprecedent millivolt-scale modulation of the optical response of plasmonic heterostructures that incorporate Ag/Al2O3/ITO material heterostructures . Specifically, we find that this behavior arises from a new mechanism for modulation of optical reflectance and transmittance, which occurs via the ionic conduction-mediated nucleation and growth of Ag nanoparticles in a conducting oxide matrix. Our plasmonic heterostructure active region consists of nanostructured silver and indium tin oxide (ITO) electrodes separated by a thin alumina layer that resemble the solid-electrolyte interface in a thin film battery. When ITO is biased negatively with respect to silver, silver ions migrate through alumina dielectric into ITO leading to nucleation and growth of silver nanoparticles in the ITO, which alter the optical extinction response. Notably, this nucleation mechanism for reflectivity modulation is distinct from previously-reported optically memristive structures. Also remarkably, reflectivity changes are observed at applied biases as small as one millivolt. We find that this ionic transport induced nucleation mechanism can explain the observed relative 30% reflectance increase in heterostructures upon application of modulation voltages as low as 5 mV. To the best of our knowledge, this is lowest ever reported modulation voltage for an observable reflectivity change in an optoelectronic device.
First, we study Ag/Al2O3/ITO planar heterostructures under electrical bias applied between Ag and ITO. The fabricated planar structures consist of 80 nm thick silver followed by 5 nm thick Al2O3 and 110 nm thick ITO. The transmission electron microscopy images gathered from never modulated sample show well-defined material layers with no material intermixing. On the other hand, the TEM image taken from the repeatedly modulated sample show large material clusters (5-10 nm in diameter) which increase in concentration and size when approaching ITO/air interface. Energy-dispersive X-ray spectroscopy measurements indicate up to 5.2% of silver present in those regions of ITO. We also fabricated resonant plasmonic heterostructures that show up to 15% change in reflectance in the visible spectral range upon application of 5 mV and 78% change in reflectance upon application of 100 mV of bias.
 U. Koch, C. Hoessbacher, A. Emboras, J. Leuthold, Optical memristive switches, J Electroceram. (2017).
 K. Thyagarajan, R. Sokhoyan, L. Zornberg, H.A. Atwater, Millivolt modulation of plasmonic metasurfaces via ionic conductance, Advanced Materilas DOI: 10.1002/adma.201701044, 2017.
EM03.06: Hot Electrons
Tuesday PM, November 28, 2017
Hynes, Level 1, Room 104
10:15 AM - *EM03.06.01
Hot Electrons Nanoscopy and Spectroscopy (HENs)
Enzo Di Fabrizio 1 Show Abstract
1 Physical, Biological and Engineering Divisions, King Abdullah University of Science and Technology, Thuwal-Jeddah Saudi Arabia
Surface plasmon polaritons can decay to form highly energetic (hot) electrons in a process that is usually thought to be parasitic as it limits the lifetime and propagation length of surface plasmons polaritons. However, it has been recently shown that hot electrons produced by surface plasmons decay can find application in photodetection, catalysis and solar energy conversion. Here we show that adiabatic focusing of surface plasmons on a Schottky junction terminated tapered tip of nanoscale dimensions allows plasmons to decay in hot electrons with conversion efficiency up to ∼30%. With such a high efficiency, hot electrons can be used for a new nanoscopy technique based on an atomic force microscopy set-up . We will show recent results on 2D materials. We show that this hot electrons nanoscopy preserves the chemical sensitivity of the scanned surface and has a spatial resolution down to 3 nm . References:  Nanoscale chemical mapping using three-dimensional adiabatic compression of surface plasmon polaritons F. De Angelis, et al. Nature nanotechnology 5 (1), 67-72, 2009;  Hot-electron nanoscopy using adiabatic compression of surface plasmons A Giugni, et al, Nature nanotechnology 8 (11), 845-852,2013
10:45 AM - EM03.06.02
Subpicosecond All-Optical Modulation in a Plasmonic Metalattice Enabled by Hot-Electron Relaxation Dynamics
Mohammad Taghinejad 1 , Hossein Taghinejad 1 , Sean Rodrigues 1 , Wenshan Cai 1 Show Abstract
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Transitioning from electronic to all-optical data processing and switching has been a long-standing goal in modern nanophotonics and plasmonics research. To create active device platforms, capable of efficient modulation of optical signals with miniaturized footprints, the development of nonlinear optical properties plays a key role. In particular, the third-order optical Kerr nonlinearity, defined as the intensity-dependent change in the real and imaginary parts of the refractive index, has been extensively employed for the demonstration of all-optical modulators. Because of the inherently weak nonlinear response of materials, a reasonable modulation depth is achievable only at the expense of enormous energy consumption. Plasmonic metals, however, enhance nonlinear photon-photon interactions through the coupling of light to surface plasmon resonances and thus offer one of the largest optical Kerr nonlinearities. In nanostructured metals, the Kerr nonlinearity originates from the photoexcitation of electrons into the conduction band, which creates a nonequilibrium electron distribution with an elevated electron temperature. The modification of electron temperature and density significantly changes the dielectric permittivity, which leads to efficient modulation of plasmonic response at low light intensity. However, the modulation speed in metal-based plasmonic modulators is still a concern, as the phonon-dominated relaxation mechanisms limits the switching speed to a few picosecond timescale. In this work, we demonstrate femtosecond (~ 190 fs) all-optical modulation by employing ultrafast kinetics of hot-electron injection at the interface of plasmonic metals and electron acceptor materials, through a comprehensive set of pump-probe transient measurements. Our experimental findings prove that activation of hot-electron relaxation pathways screen the contribution of electron-photon interactions and instead provide an electron-dominated relaxation mechanism. We employ a carefully designed plasmonic metalattice that supports spectrally tunable dark lattice modes, to maximize the density of generated plasmonic induced hot-electrons over a wide spectral range. Femtosecond all optical modulation with dynamic tuning of the modulation depth, modulation speed, and operation wavelength for either spatially confined plasmonic modes or propagating lattice modes are experimentally demonstrated in this study. We believe our results set a new benchmark for future metal-based plasmonic all-optical modulators.
11:00 AM - EM03.06.03
Mid-Infrared Plasmon-Coupled Radiation in Graphene under Ultrafast Optical Excitation—The Role of Hot Carriers in Radiative Emission
Laura Kim 1 , Seyoon Kim 1 , Victor Brar 2 , Harry Atwater 1 Show Abstract
1 , California Institute of Technology, Pasadena, California, United States, 2 , University of Wisconsin–Madison, Madison, Wisconsin, United States
The decay dynamics of excited carriers in graphene have attracted wide scientific attention, owing to the much lower relaxation rate of excited ‘hot’ carriers than that seen in many three-dimensional materials, owing to Dirac electronic dispersion. Plasmons in graphene can significantly reduce the lifetime of photoexcited charge carriers, and this plasmon effect on excited state decay is larger with increasing carrier density, as indicated by recent theoretical studies and ARPES experiments[1,2,3,4].
We report experimental demonstration of gate-tunable mid-infrared radiation from graphene under ultrafast optical pumping, and our experimental results suggest that graphene plasmons excited by ‘hot’ carriers affect the radiative emission rate. This work has important implications for achieving ultrafast optical control of mid-infrared light emission. While traditionally achieving control of infrared radiation has required heating and cooling of an object – a relatively slow process – plasmon-assisted light emission resulting from sub-100fs decay of hot carriers could provide a method for ultrafast generation and modulation of infrared light.
Plasmon emission is difficult to observe in planar graphene sheet because emitted plasmons decay non-radiatively, owing to the large momentum mismatch between graphene plasmons and free space light. Radiative emission of graphene plasmons can be dramatically increased by defining nanoribbons in graphene. We will present plasmon-coupled light emission from both planar and patterned graphene. Using infrared spectroscopy measurements of emission under ultrafast optical pumping with a Ti:sapphire laser operating at 850nm with 100fs pulse duration, we observe broad plasmon-coupled radiative emission from planar graphene with features across an energy range spanning above and below the optical phonon energy (∼5-8um or ∼150-250meV). By contrast, the radiative emission spectra from graphene nanoribbons show emission narrowly peaked exclusively at their resonant frequencies (e.g., ∼7.5um for 50nm ribbons), and the emission peaks blue shift with carrier density. In both cases, the emission intensity is larger for higher carrier densities, which is controlled via applying gate voltage. By comparing the emission spectra of bare and patterned graphene, we study the effects of propagating and confined plasmons on hot carrier decay mechanisms and the resulting light emission.
1. A. Bostwick, T. Ohta, T. Seyller, K. Horn, E. Rotenberg, Nature Phys., 2007, 3(1), pp.36-40.
2. A. Bostwick, F. Speck, T. Seyller, K. Horn, M. Polini, R. Asgari, A. H. MacDonald, E. Rotenberg, Science,
2010, 328(5981), pp.999-1002.
3. F. Rana, J. H. Strait, H. Wang, C. Manolatou, Phys. Rev. B, 2011, 84(4), pp.045437
4. I. Kaminer, Y. T. Katan, H. Buljan, Y. Shen, O. Ilic, J. J. López, L. J. Wong, J. D. Joannopoulos, M. Soljačić,
Nat. Commun., 2016, 7.
5. V. W. Brar, M. S. Jang, M. Sherrott, J. J. Lopez, H. A. Atwater, Nano Lett., 2013, 13(6), pp.2541-2547.
11:15 AM - EM03.06.04
A Comparison of Photocatalytic Activities of Gold Nanoparticles Following Plasmonic and Interband Excitation and a Strategy for Harnessing Interband Hot Carriers for Solution Phase Photocatalysis
Rong Ye 1 2 3 , Jie Zhao 1 , Son Nguyen 1 4 , Baihua Ye 1 , Horst Weller 4 , Gabor Somorjai 1 2 3 , A. Paul Alivisatos 1 2 3 , F. Toste 1 2 Show Abstract
1 , University of California, Berkeley, Berkeley, California, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States, 3 , Kavli Energy NanoScience Institute, Berkeley, California, United States, 4 , The Hamburg Centre for Ultrafast Imaging, Hamburg Germany
Light driven excitation of gold nanoparticles (GNPs) has emerged as a potential strategy to generate hot carriers for photocatalysis through excitation of localized surface plasmon resonance (LSPR). In contrast, carrier generation through excitation of interband transitions remains a less explored and underestimated pathway for photocatalytic activity. Photoinduced oxidative etching of GNPs with FeCl3 was investigated as a model reaction in order to elucidate the effects of both types of transitions. The quantitative results show that interband transitions more efficiently generate hot carriers and that those carriers exhibit higher reactivity as compared to those generated solely by LSPR. Further, leveraging the strong π-acidic character of the resulting photogenerated Au+ hole, an interband transition induced cyclization reaction of alkynylphenols was developed. Notably, alkyne coordination to the Au+ hole intercepts the classic oxidation event and leads to the formation of the catalytically active gold clusters on subnanometer scale.
11:30 AM - EM03.06.05
Excited State and Quantum-Engineered Photonic Materials
Prineha Narang 1 Show Abstract
1 John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
Excited state photonics and plasmonics finds a broad range of applications in biosensing, positioning, navigation, and timing platforms, devices for quantum information processing as well as high-resolution imaging. In this talk I will provide a fundamental understanding of plasmon-driven hot carrier generation and relaxation dynamics in the ultrafast (atto-picosecond) regime. I will report the first ab initio calculations of phonon-assisted optical excitations in metals as well as calculations of energy-dependent lifetimes and mean free paths of hot carriers, lending insight towards transport of plasmonically-generated carriers at the nanoscale. I will also discuss recent experimental observations of the injection of these nonequilibrium carriers into molecules tethered to the metal surface and into wide bandgap nitride semiconductors.
An unconventional and recent direction in excited state quantum devices is based on quantum mechanical phenomena in natural energy conversion systems, namely photosynthesis. I will show recent calculations that probe the fundamental optical physics of cavities coupled to the elaborate topology of light-harvesting complexes. This understanding will enable rational control of photonic energy transfer at the molecular scale using spatially programmable nanoscale materials inspired by natural photosynthetic systems.
11:45 AM - EM03.06.06
High-Resolution Optical Imaging Using ENNZ-Metamaterial-Lined Aperture Arrays
Elham Baladi 1 , Mitchell Semple 1 , Ashwin Iyer 1 Show Abstract
1 , University of Alberta, Edmonton, Alberta, Canada
One of the most well-known challenges in imaging scenarios is capturing the subwavelength features of an object, or distinguishing between two closely spaced objects. Imaging in general is limited by the diffraction limit, which establishes that the smallest feature that can be imaged with a wavelength λ is approximately λ/(2NA), where NA is the numerical aperture. A further challenge is the representation of this subwavelength information in the far field, and recent efforts to address this challenge have yielded devices such as the metamaterial hyperlens and mechanisms for evanescent-to-propagating conversion. In this work, we describe an entirely different approach based on the use of resonant, yet subwavelength apertures.
Recently, it was shown in the microwave regime that subwavelength circular apertures can be made resonant by means of loading them with a thin, epsilon-negative and near-zero (ENNZ) metamaterial liner, resulting in a form of extraordinary transmission (EOT) at frequencies that do not depend on spacing between apertures and are solely determined by liner properties. We have previously suggested that a nonuniform 1D array of compact ENNZ-metamaterial-lined apertures, by virtue of their differing resonance frequencies, can enable far-field high-resolution imaging of conducting obstacles at microwave frequencies.
In a separate abstract at this conference, we show that such subwavelength, closely spaced apertures can be implemented in the optical regime as well by employing plasmonic ENNZ liners. These apertures are designed at 193 THz on a gold-coated LiF substrate. In this work, we show that the resonance frequencies of these metamaterial-lined optical apertures can be controlled – just as they were at microwave frequencies – by changing their size and/or plasmonic ENNZ liner properties. A 1D nonuniform array of such apertures can be used as an imaging system, since each resonance frequency in the transmission spectrum may be associated with a unique spatial location. As each aperture shows a fano-like line shape, the resonance frequencies are designed so as to place each aperture’s resonance at the antiresonance frequency of the adjacent aperture, which ensures adjacent resonances are highly decoupled. This means that the presence of an obstacle in the vicinity of one resonator should have a minimal effect on the remaining resonances in the transmission spectrum. Therefore, these apertures can magnify to the far-field the features of a distribution of obstacles with a detection threshold equal to the aperture sizes (~λ/6.5, or 3 times below the diffraction limit), and a resolution equal to the aperture spacing (~λ/5). The proposed device suggests several important applications in biological imaging, high-resolution material testing, and defect detection.
EM03.07: Two-Dimensional Plasmonic Materials
Tuesday PM, November 28, 2017
Hynes, Level 1, Room 104
1:30 PM - *EM03.07.01
Plasmon and Photon Excitations in Two-Dimensional and Layered Materials
Harry Atwater 1 Show Abstract
1 , California Institute of Technology, Pasadena, California, United States
The study of light-matter interactions in layered and two-dimensional materials represents a method to both achieve extreme optical confinement, approaching the atomic scale, and also a tool for observing and exploring new materials phenomena. Layered narrow bandgap and zero bandgap materials such as bismuth antimony telluride, black phosphorus, and graphene support unusual and intriguing quantum-confined electronic states in thin layers and topological surface electronic states. These give rise to interesting wave propagation and dispersion features, and are expected to exhibit remarkable new optical phenomena and energy conversion mechanisms, such as gapless infrared photo-detection, gate-tunable, long-lived Dirac plasmons, and hybrid spin-plasmon modes. We report on experiments that help us to understand the nature of photon and plasmon excitations layered and two-dimensional quantum materials such as black phosphorus and bismuth antimony telluride. We describe optical interband and plasmon excitations in narrow bandgap layered semiconductors such as phosphorene (black phosphorus), and explore how strong electrostatic fields alter the band occupancy and electronic structure of thin narrow bandgap semiconductors. The anisotropic in-plane crystal structure of black phosphorus as well as it optical and electronic properties allow polarization-tunable light-matter interactions, and we report electronically tunable birefrigence in black phosphorus. We also report the nature of plasmon excitations in the conducting surface states of topological insulators, such as ultrathin bismuth antimony telluride heterostructures, and discuss how spin-charge coupling affects plasmons and other optical excitations in topological insulators.
2:00 PM - EM03.07.02
Mechanically Reconfigurable Crumple-Nanostructured Graphene for Tunable Plasmonic Resonances from Near-Infrared to Mid-Infrared
Pilgyu Kang 1 2 , Kyoung-Ho Kim 3 , Hong-Gyu Park 3 , SungWoo Nam 1 Show Abstract
1 Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Department of Mechanical Engineering, George Mason University (current affiliation), Fairfax, Virginia, United States, 3 Department of Physics, Korea University, Seoul Korea (the Republic of)
Graphene nanostructures with various geometries have been explored for a broad range of plasmonic applications. Graphene nanostructures allow high spatial confinement of graphene plasmons to induce plasmonic resonances. Although the plasmonic resonances are gate-tunable, it is challenging to achieve broadband tunability across wavelength ranges from near-infrared to mid-infrared. Moreover, graphene nanostructure patterns are not post-fabrication reconfigurable and their resonance wavelengths are fixed. Recently, it has been shown that mechanical crumpling of graphene can create various structures such as crumple nanostructures. Crumpled graphene nanostructures were shown to be mechanically reconfigurable to have varying crumple wavelength and height. Yet, the potential of crumple-nanostructured graphene for mechanical reconfigurability of plasmonic resonances has not been explored.
We present a novel approach to strong plasmonic resonances with broadband tunability based on mechanically reconfigurable crumpled graphene structures. Graphene plasmons are confined in the crumpled graphene nanostructures to be resonant and induce strong plasmonic resonances. The reconfiguration of crumpled graphene structures with varying crumple wavelength and height enables the modulation of plasmonic resonances over a five times broader range of tunable wavelengths than that achievable by conventional electrical tuning of graphene. Moreover, we show efficient excitation of graphene plasmons in crumpled graphene structures by far-field coupling of light. Strong far-field plasmonic resonances enable optical absorption enhancements up to the theoretical maximum value of 0.5. Strong confinement of the excited plasmons in crumpled graphene allows high near-field enhancements in the order of approximately 1×104 with biaxially crumpled graphene flakes. Furthermore, we show that finite-area crumpled graphene flakes allow a platform for strong light-matter interactions. The strong light-matter interaction enables large decay rate enhancements of the Purcell factor up to about 1.6×105. Our crumpled graphene structures with strong and broadly tunable plasmonic resonances from near-infrared to mid-infrared will find broad applications, including ultrasensitive biological and chemical sensing, photonic and optoelectronic devices, and light harvesting.
2:15 PM - EM03.07.03
Reconfigurable Graphene-Gold Mid-Infrared Metasurfaces for Active Beam Steering
Michelle Sherrott 1 , Philip Hon 2 , Katherine Fountaine 2 , Juan Garcia 2 , Samuel Ponti 2 , Victor Brar 3 , Luke Sweatlock 2 , Harry Atwater 1 Show Abstract
1 , California Institute of Technology, Pasadena, California, United States, 2 NG Next Nanophotonics and Plasmonics Labs, Northrop Grumman Corporation, Redondo Beach, California, United States, 3 Physics, University of Wisconsin–Madison, Madison, Wisconsin, United States
Metasurfaces are powerful structures for controlling far-field light propagation through the engineering of the amplitude, polarization, and phase at an interface. By incorporating active components into metasurfaces, it is possible to realize different optical functionalities such as lensing and far-field steering that can be adjusted in real time. There are a number of different ways to realize this active functionality, including mechanical modulation, phase change materials, and electrostatic control. Of these, electrostatic modulation offers the potential benefit of very fast switching speeds, as well as low power consumption and a small device footprint, making it a very promising approach for realizing practical photonic devices. We report here the phase modulation of an electronically reconfigurable metasurface and demonstrate its utility for mid-infrared beam steering in a multi-pixel device.
Using a gate-tunable graphene-gold resonator geometry, we demonstrate highly tunable reflected phase at multiple wavelengths. The design is based on a gap plasmon mode supported by a 1.2 μm gold bar resonator coupled to a gold back-plane with a 500 nm SiNx spacer. The resonators are spaced laterally by 50 nm with graphene in the gap, resulting in a resonance that is very sensitive to the graphene permittivity. As a gate voltage is applied to the graphene and its carrier concentration is increased, its permittivity decreases, shifting the resonant absorption peak to higher frequencies. This corresponds to a substantial modulation of phase at a fixed frequency. We measure this phase modulation using an infrared Michelson interferometer setup, and show up to 237° active range at an operating wavelength of 8.50 μm, the largest achieved electrostatically to date in the infrared. We observe a smooth monotonic modulation of phase with applied voltage from 0° to 206° at a wavelength of 8.70 μm, allowing the design of a metasurface with near-continuously available phases as a function of voltage. We extend these results to demonstrate tunable beam steering with a 1D multi-pixel metasurface with individually electrically addressable elements. We calculate using antenna array theory an absolute steering efficiency of 1% up to 30° steering angle based on the experimentally realized phase and absorption ranges. We will show active modulation of beam steering angle using this design, opening up the possibility for a wide range of applications in tunable metasurfaces.
 Michelle C. Sherrott, Philip W. C. Hon, Katherine T. Fountaine, Juan C. Garcia, Samuel M. Ponti, Victor W. Brar, Luke A. Sweatlock, Harry A. Atwater, Nano Lett., 2017, 17 (5), pp 3027–3034
2:30 PM - *EM03.07.04
Plasmon Resonances of Highly Doped Two-Dimensional MoO3 and MoS2
Kourosh Kalantar-zadeh 1 , Jian Zhen Ou 1 Show Abstract
1 , RMIT University, Melbourne, Victoria, Australia
Recently, plasmonics of 2D materials have attracted significant attention due to their desirable dispersion relation. According to the 2D dispersion equation, the cutoff frequency limit is eliminated. Additionally their large tuneability, high doping (ultradoping) range, and the existence of favorable depolarization factors allow for their better control. Among 2D materials, molybdenum disulfide (MoS2) and molybdenum oxide (MoO3) have recently received increased attention. Here, tunable plasmon resonances in suspended 2D molybdenum oxide and molybdenum sulfide flakes are demonstrated.
The 2D configuration generates a large depolarization factor and the presence of ultra-doping produces visible-light plasmon resonances. The ultra-doping process is conducted by reducing the semiconducting 2D MoO3 flakes using simulated solar irradiation. The generated plasmon resonances are controlled by the doping levels and the flakes’ lateral dimensions, as well as by exposure to a model protein.
Alternatively, by electrochemically intercalating lithium into 2D MoS2 nanoflakes, plasmon resonances in the visible and near UV wavelength ranges are achieved. These plasmon resonances are controlled by the high doping level of the nanoflakes after the intercalation, producing two distinct resonance peak areas based on the crystal arrangements. The system is also benchmarked for biosensing using bovine serum albumin.
This work provides a foundation for developing future 2D MoO3 and MoS2 based biological and optical units.
 Alsaif, M. M. Y. A.; Latham, K.; Field, M. R.; Yao, D. D.; Medehkar, N. V.; Beane, G. A.; Kaner, R. B.; Russo, S. P.; Ou, J. Z.; Kalantar-zadeh, K. Adv. Mater. 2014, 26, 3931−3937
 Wang Y., Ou J. Z., Chrimes A. F., Carey B. J., Daeneke T., Alsaif M. M. Y. A., Mortazavi M., Zhuiykov S., Medhekar. N., Bhaskaran M., Friend J. R., Strano M. S., Kalantar-zadeh K., Nano Lett, 2015, 15, 883-890
EM03.08: Phase-Change Materials
Tuesday PM, November 28, 2017
Hynes, Level 1, Room 104
3:30 PM - *EM03.08.01
Nanoscale Control over Optical Singularities
Guy Bartal 1 Show Abstract
1 , Technion, Haifa Israel
Wave-fronts containing screw dislocations, also known as Optical Vortices (OV) are singularity points in the Electromagnetic fields where the intensity is zero and the phase of the field circulates around it. OVs carry an orbital angular momentum and can be used to trap and manipulate nanometer-sized particles, assist in spatial resolution beyond diffraction limit and provide new schemes for light-matter interactions. Nano-scale control over such singularities opens up a new degree of freedom in exciting applications such as light-matter interaction on a chip, molecular motors and super-resolution imaging. Here, we present a continuous nano-scale tuning of the spatial location of optical singularities on metal-air interface, utilizing the breakdown of high-order Bessel beams in the presence of perturbation. We achieve this control by varying the polarization state of the light coupled to surface plasmons through a spiral slit, thereby controlling phase and amplitude relations between two plasmonic Bessel beams of different orders. We demonstrate such a control at nano-scale resolution using phase-resolved near-field microscopy.
4:00 PM - EM03.08.02
Thermal Switching of Ultraviolet-Visible Optical Phase in Lithography-Free Plasmonic Metamaterials
Johann Toudert 1 2 , Antonio Mariscal 1 , Marina Garcia 1 , Amanda Petford-Long 3 4 , Rosalia Serna 1 Show Abstract
1 , Laser Processing Group, Instituto de Opttica, IO-CSIC, Madrid Spain, 2 , ICFO, Castelldefels, Barcelona, Spain, 3 Material Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 4 Materials Science and Engineering Dept., Northwestern University, Evanston, Illinois, United States
Photonic technologies require the development of compact and lightweight devices suitable for blocking, filtering, focusing, coupling or outcoupling light, and controlling its polarization and phase. Plasmonic metamaterials enable such functionalities at selected frequencies that can be set from the ultraviolet to the infrared by choosing adequately their components and structure.1-3 However, many of them enable only a static control of the properties of light whereas fully functional devices require dynamically tunable optical properties that could shape light on demand and in real-time.4 At such aim, the so-called switchable plasmonic metamaterials have been developed and show already excellent performance as tunable absorbers. However, using them as high-throughput tunable polarizers or phase shifters remains a challenge, especially in the ultraviolet-visible region.
We will report two simple plasmonic metamaterial designs fabricated by bottom up physical deposition without lithography. These metamaterial structures allow the thermal switching of the optical phase of visible and ultraviolet light, with a low absorption of the incident beam. The first design consists of size- and shape- controlled noble metal nanostructures sandwiched between dielectric spacers, and the second of 2d assemblies of phase-change bismuth nanostructures embedded in a robust dielectric matrix. In both designs, the nanostructure size, shape and organization drive the topological optical darkness conditions of the metamaterial, which can be achieved at the desired angle of incidence and photon energy even outside of the range of plasmonic absorption. Around the topological optical darkness conditions, we will show that optical phase switching can be achieved by a change of a few oC around a critical temperature that can be deliberately fixed by material design. Especially, using the phase-change bismuth nanostructures that can be molten and solidified around 270oC opens the way to a higher temperature operation compared with noble metal nanostructures.
1. V. Kravets, F. Schedin, R. Jalil, L. Britnell, R. Gorbachev, D. Ansell, B. Thackray, K. Novoselov, A. Geim, A. Kabashin, and A. Grigorenko, Nature Mater. 2013, 12, 304.
2. J. Toudert, X. Wang, C. Tallet, P. Barois, A. Aradian, V. Ponsinet, ACS Photonics 2015, 2, 1443.
3. H. Song, N. Zhang, J. Duan, Z. Liu, J. Gao, M.H. Singer, D. Ji, A. R. Cheney, X. Zeng, B. Chen, S. Jiang, Q. Gan, Adv. Optical. Materials 2017, 1700166.
4. J. Park, J-H. Kang, S. J. Kim, X. Liu, M.L. Brongersma, Nano Lett. 2017, 17, 407.
4:15 PM - EM03.08.03
Deep Sub-Wavelength Phase Coexistence Patterning of Phase Change Materials by Means of Ion Irradiation
Martin Hafermann 1 , Jura Rensberg 1 , Carsten Ronning 1 Show Abstract
1 Institute of Solid State Physics, Friedrich Schiller University, Jena Germany
Phase change materials (PCMs) such as the ternary compound chalcogenide GeSbxTey (germanium-antimony-telluride, GST) enable the fabrication of reconfigurable devices like rewritable optical data storage media. In such devices switching between two states, an amorphous and a crystalline phase, is usually accomplished by applying intense laser pulses. The two states show a tremendous difference of the optical and electrical properties. Direct laser writing has also been used to create GST metasurfaces. For this purpose regular patterns of amorphous GST are created within the crystalline film or vice versa. However, the size of any pattern element is diffraction limited and cannot be smaller than the wavelength of laser light used. Thus, most of the directly structured GST metasurfaces are restricted to the near-infrared spectral region.
To circumvent the diffraction limit, we use ion irradiation combined with masking techniques like e-beam lithography. Ion irradiation induced defect formation triggers the phase transition from crystalline to amorphous in predefined regions, which enables the patterning of GST films down to structure sizes much smaller than the wavelength of visible light. Here, we demonstrate the influence of homogenous ion irradiation on the optical properties of GST thin films. These results and finite element calculation methods were used to design and fabricate sub-wavelength patterns of irradiated GST using area-selective ion irradiation. With this method we create optical elements e.g. reflective polarizers, which are investigated by Fourier transform spectroscopy. To enhance the efficiency of our devices the choice of a suitable substrate is crucial. We compare the influence of various substrates like silica and gold on the optical element performance. Our approach results in the fabrication of reconfigurable, inherently flat metasurfaces operating at visible wavelengths, which is a main desire of modern optics.
4:30 PM - EM03.08.04
Non-Volatile Phase Change Tuning of Optical Antenna Resonance
Yifei Wang 1 , Patrick Landreman 1 , Peter Zalden 1 , Scott Fong 1 , Vijay Parameshwaran 1 , Aaron Lindenberg 1 , Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States
Active tuning of nanophotonic devices has many potential applications. Such tuning can be achieved by changing either the shape or material properties of a structure. Phase-change materials, such as Germanium Antimony Tellurium (GST), are of particular interest as they can exhibit large and non-volatile changes in their refractive index. Whereas phase-changes in nanostructures of GST have been induced by pulsed laser illumination, electrical switching of GST-based optical antennas has remained elusive. Here we present optical antennas made of GST, which exploit Mie-resonance mode and can be tuned optically and electrically. By implementing phase changes in the antenna, we can shift the resonance by over the full linewidth of a resonance . This work shows potential for combining optical antenna active tuning with integrated circuit technology.
4:45 PM - EM03.08.05
Phase-Change Plasmonic Metasurfaces for Dynamic and Reconfigurable Beam Steering and Beam Shaping in the Near Infrared
Carlota Ruiz de Galarreta 1 , Arseny Alexeev 1 , Yat-Yin Au 1 , Martin Lopez-Garcia 2 , Maciej Klemm 3 , Martin Cryan 3 , Jacopo Bertolotti 1 , C. David Wright 1 Show Abstract
1 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter United Kingdom, 2 Nanophotonics Dept, International Iberan Nanotechnology Laboratory, Braga Portugal, 3 Department of Electrical and Electronic Engineering, University of Bristol, Bristol United Kingdom
Chalcogenide phase-change materials (such as GeTeSb) exhibit an abrupt refractive index change at near infrared frequencies when switching between their amorphous and crystalline states. Such a change of state can be induced, on a timescale of nanoseconds, by applying a heat stimulus which can be either thermal, optical or electrical. On the other hand, metasurfaces - arrays of subwavelength resonant inclusions - have shown the ability to offer tailored amplitude, phase, and polarization control of optical wavefronts using appropriately designed structures. During the past decade, several photonic devices based on metasurfaces, such as flat lenses, beam steerers, super absorbers, modulators and holographic generators have been reported . Recently, the combination of metasurfaces with phase-change materials has been proposed as a way to create a new type of fast, compact, tuneable and reconfigurable photonic “metadevices” [2-4]. In such phase-change based metadevices the phase-change layer acts as a form of switchable dielectric, such that very different optical properties and functionality are achieved with the phase-change layer in the amorphous and crystalline states. Importantly, in chalcogenide alloys the phase-switching is non-volatile such that amorphous and crystalline states, or indeed intermediate states, are maintained without any input power. This opens up the route for fast, low-power and fully reconfigurable photonic phase-change metadevices. In this paper we report on the design, fabrication and characterization of just such a metadevice, namely a dynamic, reconfigurable and non-volatile beam steerer working in the near infrared (1550 nm). The simplicity of our metadevice design has allowed for its successful fabrication using straightforward nanofabrication processes. Experimental angle-resolved optical characterization of devices revealed a good agreement between the simulated (via FE techniques) beam steering performance and as-fabricated device properties. With the phase-change layer in the crystalline state, our beam-steering device reflects light in a mirror-like fashion, whereas with the phase-change layer in the amorphous state anomalous reflection occurs in a preferential, pre-designed direction. We anticipate that tuneable beam-steering devices based on this approach could have several likely applications, such as in LIDAR scanning systems (e.g. for autonomous vehicles), optical beam coupling and even as surface wave couplers and decouplers.
Acknowledgment: CDW thanks the US Naval Research Laboratories by way of ONRG grant #N62909-16-1-2174, as well as the EPSRC via grants EP/M015130/1 and EP/M015173/1. CRdeG thanks the EPSRC CDT in Metamaterials (EP/L015331/1)
 Zheludev N.I. and Kivshar Y.S., Nature Materials 11, 917 (2012)
 Wang, Q., et al., Nature Photonics 10, 60 (2016)
 Hosseini, P., Wright. C.D., and Bhaskaran, H., Nature 511, 206 (2014)
 Garcia-Cuevas Carrillo, S., et al., Optics Express 24, 13563 (2016)
Stephanie Law, University of Delaware
Viktoriia Babicheva, ITMO University
Svetlana Boriskina, Massachusetts Institute of Technology
Frank Neubrech, University of Heidelberg
EM03.09: Infrared and Terahertz Plasmonics and Metamaterials
Wednesday AM, November 29, 2017
Hynes, Level 1, Room 104
8:15 AM - *EM03.09.01
Plasmonic and All-Dielectric Metasurfaces for Terahertz Applications
Oleg Mitrofanov 1 2 Show Abstract
1 , UCL, London United Kingdom, 2 , CINT, Sandia National Lab, Albuquerque, New Mexico, United States
Plasmonic and all-dielectric metasurfaces are rarely utilized for Terahertz (THz) applications. Nevertheless THz devices can benefit significantly from the functionalities offered by metasurfaces. In this presentation, selected applications, where plasmonic and all-dielectric structures are exploited to enhance efficiencies of THz devices, will be discussed.
Plasmonic nanoantennas and gratings were recently incorporated into optoelectronic THz detectors and emitters in order to improve conversion efficiency and detection sensitivity. In this application, the plasmonic structures modify effective optical properites of ultrafast photoconductors. These structures opened doors for increasing efficiencies of THz optoelectronic devices, as well as for miniaturization of their active regions. All-dielectric nano-structures have the potential for improving efficiencies of the photoconductive THz detectors and emitters even further by means of eliminating Ohmic losses, which can significantly reduce the conversion efficiency for plasmonic THz devices. We will discuss THz photoconductive detectors incorporating plasmonic and all-dielectric nano-structures.
In the THz range, some dielectric materials, such as TiO2, exhibit high values of the dielectric constants, as high as epsilon=100, substantially higher than at optical frequencies. Such high value are attractive for applications as THz metasurfaces. Dielectric properties of TiO2 however are still poorly investigated due to wide variation of the material quality. Nevertheless, our investigations of the Magnetic dipole and Electric dipole Mie resonances in single TiO2 spheres showed that intrinsic losses in this material are relatively low and it can be exploited for all-dielectric THz metasurfaces.
We will also discuss applications of the powerful THz time-domain measurement technique, which enables accessing the temporal evolution of THz fields for studies of surface plasmon waves, metasurfaces, and individual plasmonic and dielectric resonators.
8:45 AM - EM03.09.02
An Air-Spacer Terahertz Metamaterial Perfect Absorber for Sensing and Detection Application
Guangwu Duan 1 , Jacob Schalch 2 , Xiaoguang Zhao 1 , Jingdi Zhang 2 , Richard Averitt 2 , Xin Zhang 1 Show Abstract
1 , Boston University , Boston, Massachusetts, United States, 2 , UC San Diego, San Diego, California, United States
Metamaterial perfect absorbers are typically configured as metamaterials-dielectric-ground. Interacting with the incident electromagnetic wave through resonance, metamaterial perfect absorbers can realize unity absorption at specific frequencies. With the development of the theoretical support, metamaterial absorbers can potentially be employed in imaging, sensing and detection, among other applications. However, the physical presence of the dielectric spacer material precludes the accessibility to the areas between the metamaterials and the ground plane, where the electric field is highly concentrated. Also, the loss of the spacer material can damp the resonance and lower the quality factor. With air as the spacer we proved that with ohm loss alone, perfect absorption remains achievable with an even higher quality factor. Also, the absence of the spacer material yields the possibility to access the space between the MMs and the ground plane.
An array of split ring resonators (SRRs) was patterned on a silicon nitride membrane and flip chip bonded to a ground plane with polyimide as the adhesion layer at the perimeter of the array. The fabrication of the structure layer began with a double-side silicon nitride coated wafer. SRRs were patterned using lift off process with photolithography and e-beam evaporation. Next, the backside silicon nitride membrane was patterned with open windows and etched by reactive ion etching as the mask for the following wet etching, in which KOH solution was applied to completely remove the silicon at the window areas, leaving only the top side silicon nitride membranes with patterned SRRs. Another wafer was coated with gold as the ground plane, on which 10mm thick polyimide was spin coated and photolithographed. Finally, the structure layer and the ground plane were flip chip bonded by applying high temperature and force. The thickness of the air-spacer was measured as 5 mm using a microscope with digital dial indicator.
The sample was characterized using THz time-domain spectroscopy with 0° incident angle in reflection. The time domain reflection signal was measured, Fourier transferred to frequency domain, and normalized to the reference signal measured with a gold mirror. Absorption peaks were observed at the frequency of 0.811 THz for parallel polarization and 0.954 THz for perpendicular polarization with amplitude of 88.4% and 99.8%, respectively. The experimental results showed high degree of agreement with the simulation results. Numerical method was carried out to reveal the potential of the air spacer metamaterial absorber for sensing and detection applications. The relationship between the variation of the absorption spectrum and the change of the spacer permittivity indicates that the variation of the imaginary part of the permittivity predominately affects the quality factor and the absorption amplitude, while the variation of the real part of the permittivity affects mostly the absorption peak frequency.
9:00 AM - *EM03.09.03
Highly Doped Semiconductors as Designer Metals in Mid-IR
Viktor Podolskiy 1 , Daniel Wasserman 2 Show Abstract
1 , University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 , University of Texas at Austin, Austin, Texas, United States
At visible frequencies, noble metals have firmly asserted themselves as a platform for sub-wavelength optics, sensing, and as a building block for composites with engineered optical response. However, electromagnetic response of noble metals at longer wavelength is fundamentally different from their behavior at the visible frequency range. New materials platforms are needed to mold the flow of light beyond visible frequencies. Highly doped semiconductors emerge as one solution to this problem. This new class of materials enables the control over plasma frequency, thus providing an ability to tune their material response. From the theory standpoint, highly doped semiconductor materials allow to map the optics of plasmonic-noble-metals to the important mid-IR frequency range. As an added benefit, semiconductor “designer metals” can be potentially monolithically integrated into semiconductor-based (electro-) optical devices and structures. In this talk we discuss the progress of the field “designer metals” and provide an outlook for future challenges and possibilities in this field.
9:30 AM - EM03.09.04
Multi-Variable Confirmation of Dirac Plasmons in Bi2Se3 Topological Insulators
Theresa Ginley 1 , Stephanie Law 1 Show Abstract
1 , University of Delaware, Newark, Delaware, United States
Topological insulators exhibit a bulk band gap crossed by surface states with linear dispersion. These surface states comprise a Dirac cone, similar to the band structure of graphene. Due to the strong spin-orbit coupling in TIs, the surface state electrons exhibit spin-momentum locking, in which the electron spin is determined by the direction of travel. The Dirac electrons are massless and are protected by time reversal symmetry, leaving very few scattering mechanisms available and allowing the electrons to travel at relativistic speeds. Two-dimensional Dirac plasmons excited in the TIs are expected to inherit these unusual properties and have excitation frequencies in the terahertz range, a difficult band to access with traditional material systems. In TI thin films, Dirac plasmons will be excited on both the top and bottom surfaces simultaneously. These plasmons will couple, resulting in hybrid acoustic and optical plasmon modes. We are interested in understanding the properties and dispersion relationship of these coupled optical plasmon modes for eventual use in THz photonic and plasmonic devices. To map the dispersion relationship, we have measured the TI Dirac plasmon frequency as a function of film thickness and in-plane wavevector. Coupled Dirac plasmons are expected to shift to higher frequencies as the film thickness is increased and as the in-plane wavevector is increased. Bi2Se3 films of thicknesses from 45nm-200nm were grown using Molecular Beam Epitaxy and patterned into stripe arrays with stripe widths varying from 1-4mm. Then Fourier Transform Infrared Spectroscopy was used to measure the terahertz absorbance spectra of the films. Light polarized parallel to the stripes (TE-polarization) was used to determine the Drude background and phonon parameters. Light polarized perpendicular to the stripes (TM-polarization) was used to excite the Dirac plasmons. We then fit the spectra, assuming a Fano interaction between the Dirac plasmon and the TI phonons The spectra all showed a clear trend towards higher plasmon frequencies as film thickness and the in-plane wavevector increased. This research is an important step towards the observation of spin polarized plasmons. Additionally it has potential applications in tunable plasmonic metamaterials in the terahertz and optically-driven spintronics.
9:45 AM - EM03.09.05
Extending Indirect Photon Absorption and Brewster Interferometry to Both Polarizations, Broad Frequency Windows, and Unconventional Materials
Yoichiro Tsurimaki 1 , Victor Boriskin 2 , Alexander Semenov 3 , Mykola Ayzatskiy 2 , Yuri Machekhin 4 , Gang Chen 1 , Svetlana Boriskina 1 Show Abstract
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 , National Scientific Center ‘Kharkiv Institute of Physics and Technology’, Kharkiv Ukraine, 3 , Institute for Single Crystals NASU, Kharkiv Ukraine, 4 , Kharkiv National University of Radio Electronics, Kharkiv Ukraine
Photon energy harvesting with gapless materials including noble metals, graphene, graphite and topological insulators offers many exciting broadband applications in sensing, photo-detection, photo-catalysis, and solar and thermal energy conversion. However, the electronic bandstructure details as well as large mismatch between optical electron length scales reduce efficiency and bandwidth of the direct light absorptance in thin films of such materials. At the same time, surface-plasmon-mediated absorption is either limited to one polarization of incident light or requires surface nano-patterning. To alleviate these limitations, we develop photonic nanostructures composed of thin films of gapless materials (both, plasmonic and non-plasmonic) embedded into photonic nanostructures with topologically-protected interfacial photon states. These structures have planar geometry, do not require nanopatterning to achieve perfect absorption of both polarizations of the incident light, and can incorporate ultra-thin and even 2D materials as absorbers. The absorption lines are tunable across a very broad spectral range via engineering of the photon bandstructure of the underlying bulk material to achieve reversal of the geometrical (Berry) phase across the interface with the ultra-thin absorber. We will demonstrate several examples of perfect photon absorbers based on the topologically-protected interfacial states designed for operation in the visible and the infrared spectral bands. Perfect absorbers exhibit sharp phase variations at frequencies of their absorption resonances, and we will show how this effect can be used to improve the sensitivity of bio(chemical) sensors.
EM03.10: Hyperbolic Metamaterials and Metasurfaces
Wednesday PM, November 29, 2017
Hynes, Level 1, Room 104
10:30 AM - *EM03.10.01
Atomic-Scale Heterostructures—Towards Multifunctional, Active Nanophotonics in the Infrared to THz
Joshua Caldwell 1 Show Abstract
1 , Vanderbilt University, Nashville, Tennessee, United States
The field of nanophotonics is based on the ability to confine light to sub-diffractional dimensions. Two predominant types of polaritons, the surface plasmon (SPP) and surface phonon polariton (SPhP) provide the most widely investigated methods for exploring sub-diffractional confinement within the mid-wave infrared to terahertz spectral domains. Both of these optical modes offer different benefits, and also varying drawbacks. For instance, SPPs from semiconductor materials and graphene provide the capability for active tuning of the SPPs through changes in the Fermi energy, but typically have high optical losses. For SPhPs, these can be very low loss and give a great deal of additional functionality by incorporating the varying crystal structures and atomic makeup, but are limited for any given material to operate in the “Reststrahlen band”. This band occurs in the spectral range between the longitudinal and transverse optic phonons of the material. In this talk, methods for hybridizing these different optical modes and optic phonons at heterogeneous interfaces in atomic-scale heterostructures will be discussed. This hybridization provides avenues towards novel optical modes, with the incorporation and merging of material functionalities (electronic behavior, thermal conductivity, piezoelectric response, etc…) opening up the available ‘tool-box’ for the improved design of materials for nanophotonics in the infrared to THz.
11:00 AM - EM03.10.02
Volume Plasmon Polaritons in Semiconductor Hyperbolic Metamaterials
Dongxia Wei 1 , Christian Harris 2 , Stephanie Law 1 Show Abstract
1 Materials Science and Engineering, University of Delaware, Newark, Delaware, United States, 2 , Lincoln University, Oxford, Pennsylvania, United States
Hyperbolic metamaterials (HMMs) are materials whose subwavelength structure is designed to result in an anisotropic permittivity. The effective permittivity of an HMM is negative in one direction while positive in the other. This leads to an open photonic isofrequency surface that can support collective modes with large wavevectors, which would decay exponentially close to the surface in a normal material. These large wavevector modes can be used for applications like subwavelength imaging or to confine light to a subwavelength volume. Multilayered structures consisting of alternating metal/dielectric layers is one of the common ways to create an HMM. We have grown infrared HMMs using molecular beam epitaxy . In these structures, heavily-doped InAs acts as the metallic component [2,3], while undoped InAs acts as the dielectric component. For our multilayered HMMs, the aforementioned large-wavevector modes originate from the coupling of the surface plasmon polaritons at each metal/dielectric interface; these are sometimes known as volume plasmon polaritons (VPPs). To study the dispersion of VPPs in Si:InAs/InAs HMMs, we fabricated gold grating couplers with a variety of periods on the surface of our materials. The gratings match the momentum of the incident light to the large momentum of the VPPs. By changing the grating period, we can map out the dispersion of the VPP modes. We used Fourier transformed infrared spectroscopy to collect the TM and TE reflection spectra of our materials. Several VPP absorption features were observed in TM reflection, and they move to longer wavelengths with increasing grating period, as expected. Comsol Multiphysics, a commercial finite element solver, was used to simulate the behavior of our HMMs. From the simulation, we found that the scattering rate and the distribution of electrons inside the materials will strongly affect the VPP modes. Due to the small conduction band offset in the Si:InAs/InAs system, the electrons are not well confined to the Si:InAs layer. The graded interface broadens the features from the VPP modes. The study of VPPs in Si:InAs/InAs HMMs will help us understand how light propagates in the HMMs as well as the effect of interface quality on the VPP modes. It lays the foundation for potential metamaterial-based applications such as superlens, hyperlens, and enhanced detectors.
1. D. Wei, C. Harris, C. C. Bomberger, J. Zhang, J. Zide, and S. Law, "Single-material semiconductor hyperbolic metamaterials," Opt. Express 24, 8735–8745 (2016).
2. S. Law, D. C. Adams, A. M. Taylor, and D. Wasserman, "Mid-infrared designer metals," Opt. Express 20, 12155–65 (2012).
3. S. Law, L. Yu, and D. Wasserman, "Epitaxial growth of engineered metals for mid-infrared plasmonics," J. Vac. Sci. Technol. B 31, 03C121 (2013).
11:15 AM - EM03.10.03
Towards Light Extraction Limitation by Hyperbolic Metamaterials
Hung-I Lin 1 2 , Yu-Ming Liao 1 , Cheng-Han Chang 1 , Yuan-Fu Huang 1 , Wei-Cheng Liao 1 , Shih-Yao Lin 1 , Wei-Ju Lin 1 , Yang-Fang Chen 1 Show Abstract
1 Department of Physics, National Taiwan University, Taipei Taiwan, 2 Graduate Institute of Applied Physics, National Taiwan University, Taipei Taiwan
Hyperbolic metamaterials (HMMs) can greatly enhance the light extraction towards its limitation. HMMs are distinguished by their hyperbolic dispersion of iso-frequency curve in momentum-space, which allow the high-wave vector states (high-k modes) are able to be existed inside them. In this work, we first use ZnO nanoparticles as the scattering center for light extraction to prove this concept. We deposited Ag/MoO3 alternative multilayers as the HMM sample with thickness of Ag and MoO3 are 22 nm and 10 nm, respectively. Also, we prepared the precleaned SiO2/Si substrate as a reference sample. Then, ZnO nanoparticles with proper geometries were deposited on both the HMM and reference samples.
Light being scattered by passing through the randomly distributed ZnO nanoparticles may excite more high-k modes in the reciprocal space for the HMM sample, which only exist along the specific directions close to the asymptotic cone of the hyperboloid. In addition to excite high-k modes, out-coupled power reaching to the far-field rather than being trapped or annihilated inside the multilayers due to ohmic loss owing to its metal composition is also a critical issue. We can overcome this issue easily using random distribution of ZnO nanoparticles with proper geometries. To prove our proposed method, we have performed the distributions of time-resolved electric field intensity (|E|2) using finite-difference time-domain (FDTD) method for a ZnO nanoparticle with hexagonal column size (radius=40 nm, height=100 nm) placed on the HMM and reference substrates, respectively. The incident light is the plane wave with central wavelength of 388 nm. For the HMM sample, we can clearly observe that the majority of the scattered |E|2 from the ZnO nanoparticle will be out-coupled to the far-field owing to the higher transition rate from the high-k modes instead of being confined in the multilayers. The strong out-coupled effect can be realized as volume plasmon polariton (VPP), which is the result of the coupling effect from surface plasmon polariton (SPP) between the metal-dielectric interfaces. On the other hand, for the reference sample, without the assist from VPP and SPP, the majority of the |E|2 is scattered in the forward direction.
We also calculated the efficiencies (scattering cross-section (σscat) divided by its scattering cross-sectional area) for ZnO nanoparticles with a hexagonal column size influenced by the substrates. The incident field is given by: Ei=Exex+Eyey, the σscat is: ∫|T|2/k2|Ei|2dΩ, where k is the wave number, Ω is the solid angle, T=ExX+EyY and Y is the scattering amplitude for incident light with y-polarization. We can clearly see that at 388.6 nm, which corresponds to the emission of ZnO nanoparticles, the HMM reaches efficiency of 2.26, which is about 15 times higher than that of the reference sample.
This work was supported by the Ministry of Science and Technology and the Ministry of Education of the Republic of China.
11:30 AM - EM03.10.04
Evolutionary Design and Prototyping of Single Crystalline Titanium Nitride Metasurfaces
Jingtian Hu 1 , Xiaochen Ren 1 , Thaddeus Reese 1 , Amber Reed 2 , Dongjoon Rhee 1 , Augustine Urbas 2 , Lincoln Lauhon 1 , Teri Odom 1 Show Abstract
1 , Northwestern University, Evanston, Illinois, United States, 2 , Air Force Research Laboratory (AFRL), WPAFB, Ohio, United States
Compact optical components are crucial to realize miniaturized optical systems and integrated optoelectronic devices. Plasmonic metasurfaces—structured materials in 2D with rationally designed, subwavelength-scale building blocks—have drawn great interest for applications ranging from high resolution imaging to 3D holography. However, traditional plasmonic materials including Ag and Au are not compatible with current semiconducting processing. Recently, TiN has received attention as an unconventional plasmonic material because of its potential CMOS compatibility as well as exceptional mechanical strength and high-temperature stability required for operation in extreme conditions. Despite tremendous interest, there are limited reported experimental demonstration of TiN metasurfaces due to the difficulties in fabrication.
This presentation describes the design and prototyping of single-crystalline TiN plasmonic metasurfaces based on subwavelength hole arrays. An evolutionary algorithm with a multi-objective fitness function was developed to produce a variety of 3D light profiles with balanced intensities at the light spots. We also demonstrated a simple, efficient technique to prototype these lattice designs in large-area TiN films by combining focused ion beam milling and wet chemical etching. Multi-level phase control was achieved by tuning nanohole size, and multi-point focusing with arbitrary light spot patterns was realized. Using anisotropic nanohole shapes, the TiN lattice lenses could exhibit dynamic tuning of the focal profiles by changing the polarization of incident light. We believe that the reported computational design strategy and the patterning method can realize miniaturized optics and on-chip optoelectronic devices that can operate at extreme conditions.
11:45 AM - EM03.10.05
Transition Metamaterials for Local-Field Enhancement
Yang Li 1 , Philip Camayd-Muñoz 1 , Daryl Vulis 1 , Peter Saeta 1 , Yu Peng 1 , Orad Reshef 1 , Olivia Mello 1 , Haoning Tang 1 , Marko Loncar 1 , Eric Mazur 1 Show Abstract
1 , Harvard University, Cambridge, Massachusetts, United States
Nearly all forms of light-matter interaction are mediated by the electric field. Therefore, these effects can be dramatically amplified through local enhancement of the applied field. The ability to achieve significant local-field enhancement has applications in sensing, nonlinear optics, and quantum optics. Such local-field enhancement is typically achieved using free-space optics such as lenses or Fabry–Pérot etalons, or at the microscale using dielectric resonators or plasmonics. However, the field enhancement factor of these mechanisms is restricted by the focusing limit of lenses, or large mode volumes of dielectric resonators, or heating and parasitic losses of plasmonics in the optical regime. These drawbacks limit the strength of light-matter interactions and restrict applications.
Here, we present a mechanism to achieve strong local-field enhancement within a graded-index slab, where the refractive index varies from positive to negative value. Electromagnetic waves entering this material at oblique angles refract as they propagate through the slab, which can be modeled as a series of interfaces between materials with increasingly negative index. The normal component of the electric displacement field must be continuous across each interface, causing the electric field to increase as the permittivity decreases. If the index decreases gradually, the reflections at each interface can be minimized, and the incident wave can be partially transmitted through the metamaterial slab. As the wave penetrates into the slab, the electric field continues to grow until it diverges in the region where the index reaches zero.
We design a transition metamaterial based on 2D Dirac-cone metamaterials, consisting of a square array of silicon pillars. By adjusting the radius and separation of the pillars, we obtain an effective refractive index of zero with finite impedance. This design is easily extended to positive (negative) index by increasing (decreasing) the separation and radius of the pillars. A graded-index transition metamaterial can be created by continuously varying the dimensions of the unit cell across the width of the array. Using numerical simulations, we compute the enhancement of the electric field as a function of the incident angle and slab length. Results show that the field enhancement is maximized for a narrow range of incident angles, which depends on the length of the metamaterial slab. For optimized incident angles, the tangential component of the electric field Ez is enhanced by a factor of more than 400 due to the zero-index transition.
In the future work, we will fabricate the transition metamaterial based on well-established Dirac-cone metamaterial platform. We will experimentally characterize the field enhancement of the transition metamaterial through near-field scanning optical microscopy.
EM03.11: Ultraviolet Plasmonic Applications and Nanostructures
Wednesday PM, November 29, 2017
Hynes, Level 1, Room 104
1:30 PM - *EM03.11.01
Ultraviolet Plasmonics for Photocatalysis and Photodecomposition
Henry Everitt 1 2 3 Show Abstract
1 , Army AMRDEC, Redstone Arsenal, Alabama, United States, 2 Physics, Duke University, Durham, North Carolina, United States, 3 Electrical and Computer Engineering, Rice University, Houston, Texas, United States
The need to extend plasmonics into the ultraviolet (UV) spectral region - for applications including enhanced sensing of analytes, accelerated photo-degradation of toxins, and efficient photocatalytic reactions - requires the identification and use of metals that when nanostructured exhibit UV plasmonic resonances. This talk will survey our collaborative work on UV plasmonics, starting with an overview of theoretical investigations identifying candidate UV plasmonic metals, followed by a comparative review of the plasmonic properties of Ga, Rh, and Al nanoparticles. Their utility for enhanced detection and photodecomposition of various adsorbed analytes is explored by the novel use of surface-enhanced Raman spectroscopy, gas phase molecular rotational spectroscopy, and infrared spectroscopy to assess hot spot enhancement, reactant and product concentrations, and local heating, respectively. Finally, recent demonstrations of product photoselectivity for CH4 over CO in the plasmonic catalytic reduction of CO2 using Rh nanoparticles will be explored, including the sensitivity of the reaction rate to temperature, gas concentrations, nanoparticle size, wavelength and intensity of the light source, and type of metal oxide support. Challenges for discriminating plasmonic from photothermal effects in this reaction will also be described.
2:00 PM - EM03.11.02
Nanostructured Al Electrode for Plasmonic Enhancement of Organic Ultraviolet Photodetectors with High Gain
Monica Esopi 1 , Qiuming Yu 1 Show Abstract
1 , University of Washington, Seattle, Washington, United States
Incorporating surface plasmonics into optoelectronic devices can enhance the performance of devices such as solar cells and photodetectors. This effect has been well-established for metals such as Au, but has not been studied as extensively for metals with UV-range transitions such as Al. In this work, a nanostructured layer of Al was investigated with the goal of incorporation into a UV-selective organic photodetector to enhance device performance. Organic photodetectors, compared to their inorganic counterparts, offer the benefits of low material cost, tunability and flexibility. The commonly used transparent electrode indium tin oxide (ITO) prevents some of these benefits from being fully realized, as it is a relatively brittle, scarce, and expensive material with significant UV absorption. Replacing ITO with a transparent electrode that is flexible, such as a nanopatterned Al film, would enable the production of flexible devices while taking advantage of Al’s UV plasmonic properties and relative abundance and low cost. In this work, we designed and fabricated nanostructured Al films, to be used as transparent anodes in organic UV photodiode photodetectors. The device structure was Al (nanostructured) anode/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) hole transport layer/poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(bithiophene)]:[6,6]-phenyl-C71-butyric acid methyl ester (F8T2:PC71BM)/LiF electron transport layer/Al cathode. F8T2 has a wide bandgap of 2.4 eV and strong UV-selective absorption. The nanostructures of the Al thin films were designed using finite-difference time-domain (FDTD) simulations, with a unit cell including each layer in the device except for the 0.8 nm LiF. The adsorption of each layer was calculated for varied Al layer thicknesses and nanopattern geometries, while all other layer thicknesses were kept constant. The active layer absorption in the UV range was used to evaluate and optimize the nanopattern. The diameter and pitch of nanoholes and the thickness of Al thin films are critical parameters and it was found that the optimal nanopattern has a diameter of 175 nm, a pitch of 225 nm, and a thickness of 50 nm. Optimal nanopatterned films were fabricated using nanoimprint lithography on glass and PET substrates, and devices were built on top of them. The blend of active layer components heavily favors F8T2, so that PC71BM forms small, isolated clusters that act as electron traps. These trapped charges caused the F8T2 energy bands to bend down near the cathode, enabling charge injection from the Al cathode that resulted in photomultiplication. The incorporation of a nanostructured Al film, with intraband transitions relevant to UV response, enhanced this photoresponse while maintaining UV-selectivity. The knowledge and techniques developed within this work will enable advancements for photodetectors and for the broader field of optoelectronic devices.
2:15 PM - EM03.11.03
Mapping Local Electrostatic Potentials Due to Plasmon Excitation in Metal Nanostructures
Kevin Palm 1 , Joseph Garrett 1 , Tao Gong 1 , Jeremy Munday 1 Show Abstract
1 , University of Maryland, College Park, Maryland, United States
Plasmon excitation of a metal nanostructure near its resonant frequency can cause a change in its electrostatic potential as a result of charge transfer, sometime referred to as the plasmoelectric effect. While this effect has been demonstrated macroscopically, local measurements have proven difficult. Here we use fast, high-resolution Kelvin probe force microscopy methods, which we recently developed to map the open-circuit voltage of solar cells, to map surface potentials in plasmonic nanostructures under illumination. Preliminary results show voltage changes of ~100 mV upon illumination of gold and silver nanoparticles (20-60 nm in size). Further, we explore in situ manipulation of nanoparticles to control the resonance frequency of multi-nanoparticle structures. Beyond fundamental interests, control of plasmonic potentials through the manipulation of nanoparticle resonances could enable broadband plasmoelectric solar energy devices and detectors.
EM03.12: Plasmonic Color and Noble Metal Nanoparticles
Wednesday PM, November 29, 2017
Hynes, Level 1, Room 104
3:30 PM - *EM03.12.01
Dynamic Plasmonic Colour Display
Na Liu 1 Show Abstract
1 , Max Planck Institute, Stuttgart Germany
We demonstrate a dynamic plasmonic colour display technique based on catalytic magnesium metasurfaces. Controlled hydrogenation and dehydrogenation of the constituent magnesium nanoparticles, which serve as dynamic pixels, allow for plasmonic colour tuning, erasing, and restoring.
4:00 PM - EM03.12.02
Scalable Physical Coloration Based on Plasmonic Nanostructures
Tianyi Shen 1 , Domenico Pacifici 1 Show Abstract
1 School of Engineering, Brown University, Providence, Rhode Island, United States
Coloration methods based on plasmonic structures have drawn great attention in the past few years. Compared with traditional dye- and pigment-based coloration methods, physical coloration has unique advantages, such as environmentally friendly processing and resistance to degradation under UV light and moisture. Recently, plasmonic nanostructures have helped generate subwavelength-scale colorful pixels due to locally enhanced light-matter interaction. However, plasmon-assisted physical coloration approaches generally involve complicated fabrication processes, such as electron beam lithography, thus posing challenges to scalable applications.
Here, we propose a scalable physical coloration approach based on plasmonic nanostructures fabricated using nanoimprint lithography followed by deposition of thin-film dielectric coatings. The color saturation can be further enhanced by embedding a thin-film absorber (e.g., germanium or carbon) within the dielectric layer. First, three dimensional finite difference time domain (3D FDTD) simulations are performed to optimize the design of nanostructure arrays. In addition to resonant plasmonic modes, a localized photonic mode is also revealed in the structure by Fourier analysis, which can further enhance the color purity. Then, dense arrays of plasmonic nanodisks (e.g., pillars and rods) are fabricated using nanoimprint lithography. By tuning the size and periodicity of the plasmonic nanostructures, together with the thickness and position of the absorbing layer embedded in the dielectric, resonances based on plasmonic and photonic modes can be engineered to generate vivid colors. These findings may help us better understand the color generation mechanism based on plasmonic resonances and intrinsic absorbing properties of thin dielectric materials.
4:15 PM - EM03.12.03
Dynamic Plasmonic Metasurface Holograms
Jianxiong Li 1 , Na Liu 1 2 Show Abstract
1 , Max Planck Institute, Stuttgart Germany, 2 , Kirchhoff Institute for Physics, University of Heidelberg, Heidelberg Germany
Plasmonic metasurfaces represent a new class of quasi two-dimensional metamaterials that provide fascinating capabilities for manipulating light with an ultrathin platform. Such metasurfaces allow for generating a wide range of position-dependent discontinuous interfacial phase profiles. By simply engineering the metasurface-induced phase profile, a nearly arbitrary wavefront can be achieved. This unique approach promises interesting device applications beyond the scope of conventional components that rely on gradual phase accumulation for wavefront shaping. Several exotic phenomena have been demonstrated using metasurfaces including anomalous reflection and refraction, the spin Hall effect of light, plasmonic metalens, optical polarization conversion, among others. Recently, metasurfaces have been also used to achieve computer-generated holograms (CGH) with high efficiency and high image quality in the visible and near-infrared regions. The dispersionless nature of metasurfaces enables broadband operation without sacrificing the image quality. Thus, metasurface holograms feature a great advantage over other conventional methods such as CGH with spatial light modulators or diffraction optical elements.
In this work, we demonstrate dynamic plasmonic holography based on catalytic magnesium (Mg) metasurfaces in the visible range. Through the unique hydrogenation and dehydrogenation between Mg and magnesium hydride (MgH2), different information components on the plasmonic holograms become fully addressable in space and can be individually switched on/off. This results in dynamic plasmonic holograms with designated multiple states, giving rise to high-level information control with unprecedented dynamic performance. Our work outlines the inevitable transformation from metasurfaces to metadevices, opening the door to a futuristic research horizon. Such dynamic plasmonic holograms will allow for a wealth of applications for high-resolution displays, advanced security labels, high-density data storage and information processing.
 Yu, N. et al. Light Propagation with phase discontinuities: generalized laws of reflection and refraction. Science 334, 333–337 (2011).
 Zheng, G. et al. Metasurface holograms reaching 80% efficiency. Nat. Nano. 10, 308–312 (2015).
 Duan, X. et al. Dynamic plasmonic colour display. Nat. Commun. 8, 14606 (2017).
4:30 PM - EM03.12.04
Plasmonic Properties of Gold Nanoparticles in Their Assembly under Application of AC Electric Field
Kanako Watanabe 1 , Haruyuki Ishii 1 , Daisuke Nagao 1 Show Abstract
1 , Tohoku University, Sendai Japan
Assembling of plasmonic nanoparticles is important for controlling plasmonic properties of the nanoparticles. Thermosensitive polymer with volume phase transition was employed to control the distance between plasmonic nanoparticles incorporated into the polymer . Our group demonstrated a promising approach to control the assembly of particles incorporated into small voids by an external magnetic or electric field [2, 3]. An external field such as AC electric field can be applied to control the assembling state of plasmonic nanoparticles, because the nanoparticles in an aqueous suspension exhibit a high responsivity to electric field . In the present work, we applied AC electric fields from kHz to MHz range to assemble plasmonic nanoparticles. Raman spectra in the presense of targeting molecules were measured with and without an external electric field.
 P. Yui et al., Marcromol. Rapid Commun., 32, 1000-1006, 2011.
 A. Okada et al., Langmuir, 29, 9004-9009, 2013.
 K. Watanabe et al., Langmuir, 33, 296-302, 2017.
 K. D. Hermanson et al., Science, 294, 1082-1086, 2001.
4:45 PM - EM03.12.05
Metal Alloy Thin Films and Nanostructures for Plasmonics
Chen Gong 1 , Zackery Benson 1 , Alan Kaplan 1 , Mariama Rebello Sousa Dias 1 , Marina Leite 1 Show Abstract
1 , University of Maryland, College Park, Maryland, United States
Modulating the permittivity (ε) for metals will allow the unprecedented control of surface plasmon in thin films and plasmon resonance in nanostructures, ultimately leading to the design of photonic devices with superior performance. Here, we develop a new class of metallic materials with on-demand optical response . We achieve metal alloy thin films by mixing Ag, Au, and Cu with well-controlled chemical composition via a physical deposition method. We experimentally determine ε for each alloy using ellipsometry to reveal the tuning of their optical properties. We independently investigate the surface plasmon polariton coupling angle to corroborate the ellipsometry result. Further, we attain fully alloyed Ag-Au nanostructures by utilizing the de-wetting of metallic thin films. We apply cross-section energy-dispersive X-ray spectroscopy (EDS) to confirm that Ag and Au distribute uniformly within the nanostructures, forming a solid solution at the nanoscale. To show the chemical composition as another parameter for altering light-matter interactions, we combine near-field scanning optical microscopy (NSOM) with 3-dimensional full-field simulations to analyze the alloyed metallic nanostructures . We find an excellent agreement between the experimental data and the simulations. We investigate the application of alloys in perfect absorbers, where we design an AlCu/GaAs thin film structure with multi-wavelength near-unity absorption (>99%) from visible to NIR , outperforming its pure counterparts and other pure metals (Ag, Au, and Cr). The ability to engineer the optical property of metallic materials by alloying can enable the design of game-changing nanophotonic components, ranging from metamaterials and metasurfaces to nanoscale systems for energy harvesting.
 Gong, C., M. S. Leite. ACS Photonics 2016, 3, 507. Cover
 Gong, C.,§ Dias, M. R. S.,§ et al. Advanced Optical Materials 2017, 5, 1600568. (§equal contribution) Cover
 Dias, M. R. S., C. Gong, M. S. Leite. Under review 2017
EM03.13: Poster Session I: Metamaterials, Metasurfaces, Plasmonic Nanostructures and Arrays
Thursday AM, November 30, 2017
Hynes, Level 1, Hall B
8:00 PM - EM03.13.01
Fabrication of Tunable Metasurface with Broadband Refractive Index in Visible and near-IR Regime Based on Self-Assembly of Gold Nanoparticles
Reehyang Kim 1 , Kyungjae Chung 2 , Ju Young Kim 3 , Yunyong Nam 1 , Sang-Hee Ko Park 1 , Jonghwa Shin 1 Show Abstract
1 , Korea Advanced Institute of Science and Technology (KAIST), Daejeon Korea (the Republic of), 2 , Samsung Electronics, Suwon-si, Gyeongi-do, Korea (the Republic of), 3 , Electronics and Telecommunications Research Institute, Daejeon Korea (the Republic of)
Refractive index (n) can be expressed the square root of permittivity (ε) times permeability (μ): n = (εμ)1/2. Although refractive index is one of the important optical property, which governs light propagation, refraction, emission, absorption, etc., natural materials show limited value in optical frequency. In order to control refractive index, we developed new design principle for metasurface by controlling permittivity and permeability, independently. At the same time, the metasurface shows broadband characteristic based on non-resonant design principle.
Here, self-assembled gold nanoparticle (NP) array is applied to fabricate optical metasurface with broadband tunable refractive index. Without expensive nor sophisticated techniques, the simple structure which is realized by self-assembly of metal NPs is the most important advantage of the metasurface. When incident electric field is confined in between the metal NPs, due to the Thomas-Fermi screening length (~ Å). At the same time, because the skin depth of plasmonic metal (gold, silver, aluminum) is around 20 nm at optical frequency, the incident magnetic field can penetrate into the metal NPs if the size of metal NP is comparable to the skin depth. Therefore, we can control electric permittivity and magnetic permeability based on the large scale difference of Thomas-Fermi screening length and the skin depth. This design principle is already verified using numerical finite-difference time-domain (FDTD) method.
In order to fabricate broadband high refractive index metasurface in optical frequency, we use close-packed array of 11.5 nm size gold NPs based on the evaporation-induced self-assembly. For this case, the effective permittivity (ε) is enhanced by the permittivity of dielectric material surrounding the metal NPs (εh), the repeating unit cell size (a, including the size of the gold NP and the gap distance between the NPs) and the inverse of the gap distance between the NPs (g), but the effective permeability of the metasurface is sustained unity (μ ~ 1). So the effective refractive index is square root of permittivity (n = (ε)1/2 = (εha/g)1/2). The optical property of the fabricated metasurface is analyzed by spectroscopic ellipsometer and compared with FDTD calculation result. Moreover, tunability of the metasurface is also demonstrated in two different method. In mechanical approach, we stretch the fabricated metasurface on stretchable PDMS substrate to change both of the repeating unit cell size (a) and the gap distance between the NPs (g). On the other hand, we apply atomic layer deposition (ALD) method to change the dielectric material surrounding metal NP (εh).
With simple structure suggested by our resonance invariant design principle, the broadband metasurface for tunable high refractive index is well realized using self-assembly of metal NPs. It has potential application to immersion lens for lithography, solar cell, energy devices and optical communications.
8:00 PM - EM03.13.02
Active Meta-Surfaces Based on Self-Assembly Defect Engineered VO2-Metal Hybrid Film
Sungjun In 1 , Namkyou Park 1 Show Abstract
1 , Seoul National University, Seoul Korea (the Republic of)
Tunable optical devices/metamaterials/meta-surfaces provide powerful platforms for strong optical modulation, dynamic beam shaping, steering and extraordinary optical responses. Out of the commonly employed active media, such as liquid crystals , graphene  and phase-transition materials [3-8], Vanadium-Oxide (VO2) distinguishes itself with its unique advantages: reversible insulator-metal transition (IMT), complex refractive index covering visible- to micro- wavelength, abundant means in its control stimulus (optical, thermal) as well as its material properties (electron doping, structural defects, lattice strain and morphology). Various approaches including ion irradiation, nano-patterning, surface texturing, and metal doping have been studied, in order to achieve better controllability in its transition temperature, complex refractive index, and also optical responses [3-8].
Nonetheless, it is noted that the modulated optical properties of VO2 are mainly restricted in the THz and microwave regime, where the changes in its complex refractive index are large. The realization of large change in its properties in visible range, still remains as a challenge.
In this work, we demonstrate a new approach of self-assembly defect engineering, to achieve the phase-transition of VO2 with large changes in the optical properties and transition temperature. Based on a simple and cheap spin-coating process including metal deposition, we show that it is possible to selectively control the transition temperature and optical responses of VO2-metal hybrid film. As a representative application example, we demonstrate a temperature controlled color filter, at different thickness of deposited metal film. Our uncomplicated and easily controllable defect engineering will provide a new paradigm for cost- and fabrication- friendly, precision active photonic devices.
 Werner, D. H.et. al. Opt. Express 2007, 15, pp 3342−3347.
 Yao, Y. Nano Lett. 2014, 14, pp 6526−6532.
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 Rensberg, J., et al. Nano Lett., 2016, 16.2, pp1050-1055.
 Kocer, H., et al. Sci. Rep., 2015 5, 13384.
8:00 PM - EM03.13.03
Ultrahigh Enhancement of Photoluminescence for Monolayer MoS2 by Hyperbolic Metamaterials with Metal Mask
Yuan-Fu Huang 1 , Hung-I Lin 1 , Cheng-Han Chang 1 , Shih-Yao Lin 1 , Wei-Ju Lin 1 , Yu-Ming Liao 1 , Yang-Fang Chen 1 Show Abstract
1 Department of Physics, National Taiwan University, Taipei Taiwan
Two-dimensional (2D) materials are the promising materials for next generation optoelectronics by their outstanding electrical and optical properties. Especially, transition metal dichalcogenides (TMDs) have been widely used owing to its direct bandgap such as monolayer molybdenum disulfide (MoS2). However, the light emission from the monolayer 2D materials is relatively weak. Recently, many methods have been used to increase the light emission such as plasmonics and photonics nanostructures. Therefore, it is a trend to enhance the photoluminescence intensity of 2D material.
Hyperbolic metamaterials (HMMs) can be determined by their hyperbolic dispersion of iso-frequency curve in momentum-space, which allows the existence of high-k modes inside them. This unique characteristic results in the increment of photonic density of states leading the enhancement of spontaneous emission on the near-field surface of HMMs. These propagating waves of high-k modes can be underdood as the volume plasmon polariton (VPP) that can propagate inside the whole structure of HMMs.
In this study, we report the first attempt to strongly enhance photoluminescence intensity with a transmission electron microscopy (TEM)-grid to effectively excite more high-k modes from HMMs. In order to stand out the effect of the HMMs, we deposited Au/Ti as a metal mask on the monolayer MoS2 with thickness of 40 and 5 nm, respectively. Here we made four different structures for comparison. The first comparison is monolayer MoS2 on the HMMs with and without the TEM-grid, which marked as mask_HMMs and HMMs, respectively. While the second comparison is monolayer MoS2 on the silicon substrate with and without the TEM-grid, which marked as mask_Reference and Reference, respectively. To measure the photoluminescence, we used the 375 nm pulsed diode laser with fixed pumping energy density of 103 μJ/cm2. Interestingly, the photoluminescence intensity for mask_HMMs is about 3.1, 3.6 and 25.2 times stronger than that of the HMMs, mask_Reference and Reference samples, respectively. This gigantic photoluminescence enhancement for the mask_HMMs can be realized as the influenced from the VPP, which is the additional coupling effect by the surface plasmon polariton (SPP) in between the Ag and MoO3 layers, as well as the SPP effect from the metal mask. As to the HMM sample, the photoluminescence can be realized as the VPP effect, whereas the mask_Reference sample is attributed to the SPP effect. Nevertheless, without the assist from VPP and SPP, the Reference sample shows the lowest photoluminescence emission intensity.
Realizing strong enhancement of photoluminescence assisted by HMMs provides an attractive, very simple and efficient scheme for the development of high performance optoelectronic devices, including solar cells, phototransistors, and many other solid state lighting systems.
This work was supported by the Ministry of Science and Technology and the Ministry of Education of Republic of China.
8:00 PM - EM03.13.04
Fabricating Metamaterials via Atomic Calligraphy
Lawrence Barrett 1 , Thomas Stark 1 , Jeremy Reeves 1 , Richard Lally 1 , David Bishop 1 Show Abstract
1 , Boston University, Boston, Massachusetts, United States
Atomic Calligraphy is a microelectromechanical systems (MEMS) based technique for nanomanufacturing. Each atomic calligraphy "writer" consists of a 100 μm plate with nanometer scale apertures that are used to direct a flux of atoms from an evaporation source. The atomic flux is directed by moving the plate with sub-nanometer precision using comb drive actuators. Each writer has a low throughput because the process is serial, similar to a focused ion beam or electron beam lithography process. However, the power of this method is in its scalability. Because the writers are made using a standard foundry process, thousands of writers can be placed on a single chip and fabricate devices in parallel, potentially, achieving throughputs even higher than ultraviolet lithography. Here we apply this technique to the fabrication of optical metamaterials, including arrays of split ring resonators with resonances in the infrared. Additionally, we show that this technique can be used to fabricate metamaterials on substrates that are incompatible with resist based fabrication techniques, including polymers.
8:00 PM - EM03.13.05
A Multi-Functional Three-Dimensional Terahertz Metamaterial Perfect Absorber
Xiaoguang Zhao 1 , Meng Wu 1 , Jingdi Zhang 2 , Jacob Schalch 2 , Guangwu Duan 1 , Kevin Cremin 2 , Richard Averitt 2 , Xin Zhang 1 Show Abstract
1 Mechanical Engineering, Boston University, Boston, Massachusetts, United States, 2 Department of Physics, University of California, San Diego, La Jolla, California, United States
Electromagnetic (EM) absorber materials are crucial for many applications such as light trapping for solar cells, ultra-sensitive detectors, and antireflection coatings, among others. However, conventional EM absorbers are suffering from the bulk geometry due to the quarter-wavelength criterion, which must be met. The emerging metamaterial technology has enabled perfect absorption materials with ultrathin resonating structures. The response of a conventional metamaterial perfect absorber (MPA), which consists of a stacked planar metamaterial layer, dielectric spacer and ground plane, is dependent upon the incident angle due to its planar nature.
This paper will demonstrate a three-dimensional MPA, which consists of an array of stand-up split ring resonators, with a high quality-factor and wide absorption angle and reveal its potential application to chemical sensing. The standup unit cells can respond to the electric and magnetic components of the incident waves simultaneously, resulting in equal effective permittivity (ε) and permeability (μ) at the resonant frequency. Thus, the impedance of the MPA at the resonant frequency is matched with the free space, thereby eliminating reflection. At the same time, the metal ground plane blocks the transmission. All of the incident EM waves will be trapped in the resonator and absorbed due to Ohmic loss in the structure.
The 3D MPA is fabricated using a multiple layer electroplating processes and characterized by a terahertz time domain spectroscopy. A 99.6% absorption is achieved at the resonant frequency (~1.65THz) with a quality factor of 37.5. The response of the TE and TM polarization incident is identical, meaning that the MPA is polarization insensitive. To investigate the mechanism of the perfect absorption, numerical simulations using CST Microwave Studio were performed. The simulation spectrum agrees well with the experimental measurement, ensuring the accuracy of the numerical model. The simulated electric and magnetic field distributions imply that we can manipulate the effective permittivity and permeability with the resonator structure design. The incident angle and polarization dependency are also studied using simulation. The absorption is larger than 60% for 80o incident angle, demonstrating its capacity for a wide angle response. Besides wide-angle perfect absorber, the metamaterial can serve as a sensitive chemical sensor as demonstrated experimentally by the frequency shift when it is exposed to a thin layer of dielectric material.
8:00 PM - EM03.13.06
Photocurrent-Generating Aluminum and Niobium (Oxide) Plasmonic Metasurfaces for the Shortwave Infrared
Richard Osgood 1 , Yassine Ait-El-Aoud 1 , Lalitha Parameswaran 2 , Michael Okamoto 1 , Vladimir Liberman 2 , Alkim Akyurtlu 3 , Steven Kooi 4 , Mordechai Rothschild 2 , Diane Steeves 1 , Brian Koker 1 Show Abstract
1 , NSRDEC, Natick, Massachusetts, United States, 2 , Massachusetts Institute of Technology Lincoln Laboratory, Lexington, Massachusetts, United States, 3 Electrical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 4 ISN, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Arrays of microrectennas, consisting of plasmonic antennas coupled to rectifying diodes, convert incident infrared/THz light into direct current via optical rectification. Rectification is enabled by quantum tunneling and/or thermionic conduction across an insulating, ultrathin barrier layer in a Metal-Insulator-Metal (MIM) diode. Rectification of high frequency voltage from an antenna array resonating in the infrared or visible regime has been observed in single lateral junctions1 and in laboratory-scale mixing experiments, but not in parallel arrays of vertical junctions in the infrared spectrum. Arrays of plasmonic stripes (e.g., Au, Ag, Al) have been shown to act as metamaterial absorbers for the infrared,2 but nonlinear optical effects have so far not been observed. Because rectennas are fundamentally different from semiconductors with absorption tuned by metamaterial dimensions, instead of by a band gap, and because tuned rectennas have efficiently converted light in the GHz regime, they are predicted to be capable of light-harvesting and detecting different bands in the infrared regime.
Exploring applications for power transfer/detection in the Shortwave Infrared (SWIR) band, we have designed, fabricated, and analyzed Ag, Al, and Au horizontal stripe-teeth arrays, with features in the 200 nm range, lying horizontally above the barrier layer and acting as both a resonant metasurface and as an electrical contact for the vertical current. The arrays’ “teeth” break symmetry, and a net intense a.c. vertical electrical field to drive electrons across the barrier layer. The reflectivity of the Al-Al2O3-based MIM diodes, when polarized along the teeth, exhibits three peaks, whose positions depend on the teeth separation. Au stripes on NbOx barrier layers show much broader features. Au antennas are fabricated using a unique, “single-shot” electron-beam patterning technique based on imaging, instead of traditional e-beam drawing techniques.3 New architectures and and (micro, nano)structures, fabricated using precise atomic layer deposition of novel oxides (NbOx, NiO, and Al2O3) with thicknesses in the range 10 -24 nm, enable ultrafast rectification more efficiently than oxide films grown or deposited using usual deposition methods. Our cross-sectional electron microscopy (XTEM) images show low-roughness NbOx and Al2O3 films. Electrical measurements confirm this, and show that conduction is dominated by a combination of quantum tunneling and thermionic emission.4 We predict the magnitude of the rectified signal, and compare to what is observed under focused vis/ir polarized laser beam illumination, using a lock-in amplifier technique to remove slow heating effects.
 D. R. Ward, et. al., Nat. Nanotechnol. Lett. 5 (2010) 732.
 Wu, C. et. al., Phys. Rev. B 84 (2011) 075102.
 Lee, H.-S., et. al., Adv. Mater. 19 (2007) 4189.
 Osgood III, R. M., et. al., J. Vac. Sci. Tech. A 34 (2016) 51514.
8:00 PM - EM03.13.07
Compact Aperture-Array Metascreens Demonstrating EOT at Telecommunications Wavelengths
Mitchell Semple 1 , Aaron Hryciw 2 , Ashwin Iyer 1 Show Abstract
1 , University of Alberta, Edmonton, Alberta, Canada, 2 NanoFAB Facility, University of Alberta, Edmonton, Alberta, Canada
With the demonstration of extraordinary optical transmission (EOT), aperture arrays in metal films generated intense interest in controlling the reflection, transmission, and confinement of light. Plasmonic aperture arrays have found several notable applications in surface plasmon sensing, surface enhanced spectroscopy and sub-wavelength imaging. Unfortunately, EOT’s reliance on tangential diffraction orders implies that the aperture spacing must be on the order of a wavelength. If these spacings could be made sub-wavelength, the resulting compact arrays would enable sub-wavelength spatial sensing and/or imaging applications, and allow for accommodation of more aperture-array devices in a given area. Moreover, sub-wavelength spacings suggest that such a periodic surface could be called a metascreen (MTS).
In the microwave regime, it was recently experimentally shown that lining each aperture with a thin, epsilon-negative and near-zero (ENNZ) metamaterial can introduce resonant transmission at a frequency well below the usual aperture resonance frequency. This allows for miniaturization and removes the dependence on aperture spacing while keeping the aperture mostly empty. These MTSs, when translated to optical frequencies, can employ plasmonic ENNZ liners that allow subwavelength spatial control of fields for the realization of new optical phenomena or the enhancement of optical devices. For example, beam splitters with subwavelength control over phase and magnitude could be created, subwavelength spatial information could be added to surface enhanced spectroscopy and surface plasmon sensing, subwavelength pixels could be developed for extremely high density displays, and, with the use of non-linear materials, compact photonic switches could be made for optical telecommunications.
In this work, we present an optical implementation of an ENNZ-aperture-based MTS. The design was simulated using COMSOL Multiphysics with feature sizes achievable by helium focused ion beam (He-FIB) fabrication. The aperture array was designed to transmit at λ = 1.55 μm (f = 193 THz), where it could be used as a beam splitter for optical telecommunications. Gold was chosen as the metal film due to low oxidation in air and because it closely follows the lossy Drude model in the infrared domain. He-FIB was chosen for maximum flexibility in aspect ratios as well as the finest possible features. For the substrate, LiF was chosen for high transmittivity and lattice match with gold such that an epitaxial film could be grown, as He-FIB sputter rates are very sensitive to crystal boundaries. The MTS was successfully simulated with circular apertures of radius 120 nm = λ/13 and a square periodicity of 300 nm = λ/5, which allows 25 times more apertures per unit area than a comparable conventional EOT array. Fabrication using the Zeiss ORION NanoFab He-FIB is in progress, and we expect to present preliminary experimental data at the meeting.
8:00 PM - EM03.13.08
Structural Versus Plasmonic Evolution of Hybrid Ag−Ag2X (X= S, Se) Nanoprisms
Moha Shahjamali 1 , Negin Zaraee 2 , Nicolas Large 3 , George Schatz 4 , Chad Mirkin 4 Show Abstract
1 , Harvard University, Cambridge, Massachusetts, United States, 2 Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States, 3 Physics, The University of Texas at San Antonio, San Antonio, Texas, United States, 4 Chemistry, Northwestern University, Evanston, Illinois, United States
Recently, hybrid Ag−Ag2X (X= S, Se) nanostructures have attracted a great deal of attention due to their enhanced chemical and thermal stability, in addition to their morphology- and composition-dependent tunable local surface plasmon resonances. Although Ag−Ag2X nanostructures can be synthesized via reaction of Sulfur or Selenium to as-prepared anisotropic Ag nanoparticles, this process is poorly understood, often leading to materials with anomalous compositions, sizes, and shapes and, consequently, optical properties.
In this work, we use theory and experiment to investigate the structural and plasmonic evolution of Ag−Ag2X nanoprisms during the reaction. The previously observed red-shifted extinction of the Ag−Ag2S hybrid nanoprism as sulfidation occurs contradicts theoretical predictions, indicating that the reaction does not just occur at the prism tips as previously speculated. Our experiments show that S, Se reaction with Ag can induce either blue or red shifts in the extinction of the dipole plasmon mode, depending on reaction conditions. By elucidating the correlation with the final structure and morphology of the synthesized Ag−Ag2X nanoprisms, we find that, depending on the reaction conditions, it occurs on the prism tips and/or the (111) surfaces, leading to a core(Ag)−anisotropic shell(Ag2X) prism nanostructure. Additionally, we demonstrate that the direction of the shift in the dipole plasmon is a function of the relative amounts of Ag2X at the prism tips and Ag2X shell thickness around the prism.
8:00 PM - EM03.13.09
Optothermally Tuned Charge Transfer Plasmons in Au-Ge2Sb2Te5 Core-Shell Assemblies
Burak Gerislioglu 1 , Arash Ahmadivand 1 , Nezih Pala 1 Show Abstract
1 ECE, Florida International University, Miami, Florida, United States
Functional and reversible plasmonic resonances across the optical and near infrared spectrum have opened new avenues for developing advanced next-generation nanophotonic devices. In this study, by using optothermally controllable phase-changing material (PCM) in the geometry of plasmonic nanostructures, we successfully induced highly tunable charge transfer plasmon (CTP) resonant modes. To this end, we choose a two-member dimer assembly consisting of gold cores and Ge2Sb2Te5 (GST) shells in distant, touching, and overlapping regimes. We show that switching between amorphous (dielectric) and crystalline (conductive) phases of GST coverage allows for achieving tunable dipolar and CTP resonances and enables an effective interplay between these modes along the near-infrared spectrum. By analyzing electromagnetically calculated spectral responses for the dimer antenna in tunneling and direct charge transfer regimes, we confirmed that the induced CTPs in touching and overlapping regimes are highly controllable and pronounced compared to the quantum tunneling regime. We also use the precise, fast, and controllable switching between dipolar and CTP resonant modes to develop a telecommunication switch based on simple metallodielectric dimer. The proposed structures can help designing optothermally controllable devices without morphological variations in the geometry of the design, having strong potential for advanced plasmon modulation, and fast data routing.
8:00 PM - EM03.13.10
Synergistic Effects from Light and Heat in Plasmon-Enhanced Catalysis
Xueqian Li 1 , Xiao Zhang 1 , Jie Liu 1 , Henry Everitt 1 Show Abstract
1 Chemistry, Duke University, Durham, North Carolina, United States
The unique optical features of plasmonic nanoparticles offer an efficient strategy to harness light energy and create hot electron/hole pairs with energies inaccessible via thermal energy. Light energy is valuable in its entirety; it can help to enhance reactions through photo-heating, photo-modifications, and/or photo-generated hot carrier. To explicitly understand how light-induced effects enhance the non-thermal reaction rate, the temperature profile of the catalyst bed must be quantitatively characterized. Simultaneous measurements of the total reaction rate and temperature profile allow for the differentiation between thermal and non-thermal contributions, as demonstrated on illuminated rhodium photocatalysts for CO2 methanation. The non-thermal rate of the plasmon-enhanced reaction is found to grow with a super-linear dependence on illumination intensity, while the apparent quantum efficiency reaches ~46% on a Rh/TiO2 catalyst at the surface temperature of 350 °C. In traditional photocatalysis, high temperatures reduce the efficiency and lifetime of catalysts while low temperature limit the reaction speed. In contrast, light and heat is shown to work synergistically in plasmon-enhanced catalysis: the higher the temperature, the higher the overall non-thermal efficiency.
8:00 PM - EM03.13.11
Thermal Stability of the Core-Shell Structure of Plasmonic Gallium Nanoparticles—The Role of the Oxidation
Sergio Catalán-Gómez 1 , Andres Redondo-Cubero 1 , Javier Palomares 2 , Flavio Nucciarelli 1 , Nuria Gordillo 1 , Jose Luis Pau 1 Show Abstract
1 Dpt. Física Aplicada, Universidad Autonoma de Madrid, Madrid Spain, 2 ICMM, CSIC, Madrid Spain
Gallium nanoparticles (NPs) are excellent candidates for biosensing and photonic devices , due to the broad spectral range that they can cover, from the UV to the IR, in terms of the localized surface plasmon resonance. This resonance is controlled by the geometry of the NPs and the refractive index of the surrounding media . Ga NPs produced by evaporation typically exhibit a hemispherical geometry and, above a critical size, they start to merge and coarsen. When thermally evaporated NPs are exposed to air, a 0.5-3 nm thin layer (shell) of an amorphous gallium oxide is formed around the liquid Ga (core) preserving them from the environment and maintaining it in a supercooled state . In this work we study the thermal oxidation and stability of Ga NPs from 150 °C to 900 °C.
For temperatures between 150 °C and 300 °C, we observed a red-shift of the out-of-plane plasmon resonance in spectroscopic ellipsometry ascribed to an increase of the oxide thickness, and confirmed by X-ray photoelectron spectroscopy. Our discrete dipole approximation simulations demonstrate that this shift is compatible with the expected one for NPs with increasing oxide shell thickness. X-ray diffraction shows a decrease of liquid Ga broad bands according to this process.
Additionally, we also evaluated the role of the oxidation time. In this case, the redshift follows a logarithmic law which allows us to tune the plasmon resonance wavelength in a very accurate way without significant reduction of the plasmon intensity.
For high temperatures, above 450 °C, the thermal expansion and vapour pressure of the liquid gallium inside the NPs induces the oxide shell breakdown and the liquid gallium is ejected through a crater (characterized by scanning electron microscopy). At those temperatures, the formation of b-Ga2O3 around the native oxide shell is achieved, showing a good intensity in cathodoluminiscence and X-ray diffraction analysis. These results help to understand the mechanisms involved in the oxidation of the NPs and, in addition, determine the limits and possibilities for tuning the plasmon resonance by thermal treatments.
1. A. García Marín et al., Biosens. Bioelectron. 74, 1069 (2015); Nanoscale 8, 18 (2016)
2. K.A. Willets et al., Annu. Rev. Phys. Chem. 58, 267 (2007)
3. J.M. Sanz et al., J. Phys. Chem. 117, 38 (2013)
8:00 PM - EM03.13.12
Enhanced Upconversion Luminescence by Whispering Gallery Mode Resonance of Encapsulated Microbubble with Upconversion Nanoparticles
Seon Ju Yeo 1 , Jung Eun Choi 1 , Ho Seong Jang 1 , Min Jun Oh 2 , Pil Jin Yoo 2 , Seok Joon Kwon 1 Show Abstract
1 , Korea Institute of Science and Technology, Seoul Korea (the Republic of), 2 , Sungkyunkwan University, Suwon Korea (the Republic of)
Wavelength upconversion luminescence (UCL) have been increasingly utilized in a variety of areas including biosensors, photodetectors, imaging agents, and anti-counterfeit devices. In particular, for the efficient and effective luminescence, crystalline upconversion nanoparticles (UCNPs) have been incorporated into photonic platforms and plasmonic nanostructures targeting near IR (NIR)-to-Visible upconversion. Notwithstanding the photonic and plasmonic conjunction, intrinsic internal quantum efficiency (IQE) is still far behind the bar of the practical applications. In this presentation, we report on experimental and theoretical studies on whispering gallery mode (WGM) resonance which strongly contributes to the enhancement of the external quantum efficiency (EQE) as well as IQE of UCNPs. For the realization of the WGM resonance-induced UCL, we employed a microfluidic method which generates monodisperse micron-sized encapsulated bubble (or hollow sphere). In the encapsulating shell, UCNPs effectively confine the incident NIR light inside the optical cavity (bubble), which subsequently allows high Q factor with small mode volume, and high absorption coefficient, consequently. To enhance the emission of the visible UCL from the UCNPs, we also numerically designed and experimentally controlled the geometry of the bubble such as thickness and size. The controlled structures, in turn, prevent the emitted light from resonating inside the bubble, which allows higher light extraction efficiency. Conclusively, 2-orders of magnitude enhanced UCL intensity accompanied by 1- or 2-orders of magnitude enhanced internal quantum efficiency was achieved.
8:00 PM - EM03.13.13
Characterizing the Hybridized Plasmonic Response of ITO Nanostructured Dimers Using EELS
Viktor Kapetanovic 1 , Isobel Bicket 1 , Edson Bellido 1 , Gianluigi Botton 1 Show Abstract
1 , McMaster University, Hamilton, Ontario, Canada
Plasmonics is a growing field due to its ability to bridge the gap between photonics and electronics by offering sub-diffraction confinement of light . Although the plasmonic behaviours of noble metals such as Au and Ag, and Al have dominated the literature, they exhibit certain disadvantages when incorporating them into real-world applications. Tunability, stability and integration with silicon technologies are qualities that are lacking in noble metals and Al, whereas semiconductors have been shown to possess these requirements thus becoming potentially useful plasmonic materials . Indium Tin Oxide (ITO), a stable, tunable doped semiconductor, has been exploited for photovoltaic applications due to a lossless conductive IR region and transparent visible region . The combination of coupled ITO nanostructures can provide highly localized electromagnetic fields, as well as a plasmonic response deep into the IR.
The objective of this study is to fabricate customized nanostructure dimers of ITO and study the hybridized plasmonic response between them in a scanning transmission electron microscope (STEM) using electron energy loss spectroscopy (EELS). The fabrication process includes conventional microfabrication techniques (spin coating, electron beam lithography, rapid thermal annealing) and RF sputtering deposition. Simulations with the MNPBEM toolbox , which uses a boundary element method (BEM) approach, are also carried out to determine the sizes and shapes that would best show plasmon hybridization.
The surface plasmon response of ITO is below 1eV, making its experimental detection with EELS extremely challenging due to its proximity to the peak corresponding to the distribution of elastically scattered electrons. By using a monochromated STEM with a high energy resolution of about 60meV, we have been able to visualize the resonances of single ITO nanostructures down to 0.175eV. Furthermore, the intensity of the plasmon peaks was found to rely heavily on the annealing parameters within a nitrogen environment. Additional experimental work is performed to support our simulated results of coupled dimer nanostructures.
1. F. J. Garcia de Abajo, Rev. Mod. Phys. 82, 209 (2010).
2. G.V. Naik, V.M. Shalaev, and A. Boltasseva, Adv. Mater. 2013, 25, 3264–3294.
3. S. Franzen, et al., Optics Letters, (2009) 34, 18.
4. U. Hohenester and A. Trügler, Comp. Phys. Commun. 183, 370 (2012).
5. This work was carried out at the Canadian Center for Electron Microscopy (CCEM) and the Center for Emerging Device Technologies (CEDT) at McMaster. V.K, I.C.B., E.P.B., and G.A.B. acknowledge support from NSERC under the Discovery Grant Program. The Canadian Centre for Electron Microscopy is a National Facility supported by The Canada Foundation for Innovation under the MSI program, NSERC and McMaster University.
8:00 PM - EM03.13.14
Symmetry Breaking and Strongly Coupled Resonance Tuning in Dolmen Nanostructures
Swathi G.R. Iyer 1 , Chase Ellis 1 , Alexander Giles 1 , Joseph Tischler 1 , Richard Kasica 2 , Dimitry Chigrin 3 , Joshua Caldwell 4 Show Abstract
1 , Naval Research Laboratory, Washington, District of Columbia, United States, 2 Centre for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland, United States, 3 Institute of Physics, RWTH Aachen University, Aachen Germany, 4 Mechanical and Electrical Engineering, Vanderbilt University, Nashville, Tennessee, United States
Polar-dielectric materials, such as SiC, have garnered a lot of attention as they support sub-diffractional confinement of light in the mid-infrared to THz regime with very low optical losses.1 The surface phonon polariton (SPhP) in SiC, a polar dielectric, is formed when the optical phonon vibrations in the crystal lattice couple with the incident radiation. Recently, coupled phononic SiC nanostructures have received enormous attention both in basic and applied research.2, 3 In this work, we fabricate a metasurface in the form of SiC, so-called ‘dolmen’ nanostructures, consisting of two vertical rectangular pillars with fixed gap and a horizontal top pillar separated with varying gaps from semi-insulating 4H-SiC substrate. These coupled oscillators enable the creation of modified optical modes active in the Reststrahlen band region via periodicity-induced symmetry breaking. The polarization-dependent, far-field reflection studies reveal that the nanostructures exhibit very strong dipolar and quadrupolar resonances and the interaction between the radiant, broader dipolar modes with the narrow, sub-radiant quadrupolar modes gives rise to a unique asymmetric strongly coupled resonance. By controlling the geometry and spacing of the features in the dolmen we notice that the resonances can be highly tunable, resulting in exceptional optical properties highly desirable to enhance the performance of various nanophotonic applications.
J. D. Caldwell, L. Lindsay, V. Giannini, I. Vurgaftman, T. L. Reinecke, S. A. Maier and O. J. Glembocki, Nanophotonics, 4: 44, 2015.
J. D. Caldwell, O J. Glembocki, Y. Francescato, N. Sharac, V Giannini, F.J. Bezares, J. P. Long, J. C. Owrutsky, I. Vurgaftman, J. G. Tischler, V. D. Wheeler, N. D. Bassim, L. M. Shirey, R. Kasica, and S. A. Maier, Nano lett., 13, 3690, 2013.
C. T. Ellis, J. G. Tischler, O J. Glembocki, F. J. Bezares, A. J. Giles, R. Kasica, L. M. Shirey, J. C. Owrutsky, D. N. Chigrin, J. D. Caldwell Sci. Rep., 6, 32959, 2016.
8:00 PM - EM03.13.15
Semiconductor Nanopillar-Metal Shell Plasmonic Cavity for Advanced Optoelectronics
Stanislav Tsoi 1 , Daniel Ratchford 1 , Igor Vurgaftman 1 , Pehr Pehrsson 1 Show Abstract
1 , US Naval Research Laboratory, Washington, District of Columbia, United States
Recent experimental studies have demonstrated that a plasmonic cavity, consisting of a metallic shell over a semiconductor nanopillar, can enhance the efficiency of photodetectors1 and light sources.2 However, the nature of the cavity plasmons responsible for the enhanced device operation remains unknown. In the present work, a cavity is fabricated by evaporating gold on arrays of Si nanopillars. The resulting cavities on individual nanopillars consist of a metallic cap on top of each Si nanopillar and an incomplete shell over its sidewall. In addition, a continuous metal floor forms between the nanopillars. A series of the cavity arrays with systematically varying heights (150 – 350 nm) and cross-sectional diameters (135 – 350 nm) are thus obtained. Reflectivity recorded from the arrays reveals several strong, polarization-dependent resonances, which shift to lower energy with the increasing diameter. Numerical simulations using the COMSOL package reproduce with good fidelity the spectral positions and polarization dependence of the observed resonances. To determine the physical nature of the resonances, the metallic shell of the cavity is systematically varied. Resulting reflectivity changes, in conjunction with the simulations, suggest that the lowest energy resonance – observed in the spectral range from 1.8 µm to 3.5 µm – is due to a cavity dipole plasmon of the gold shell, concentrating electromagnetic field inside the semiconductor core.
1Nano Lett. 16, 199 (2016).
2ACS Photonics 4, 795 (2017).
8:00 PM - EM03.13.16
High-Index Dielectric Nanowires for Strongly Directional Light Scattering
Peter Wiecha 1 , Aurelien Cuche 1 , Arnaud Arbouet 1 , Christian Girard 1 , Gérard Colas des Francs 2 , Aurelie Lecestre 3 , Guilhem Larrieu 3 , Frank Fournel 4 , Vincent Larrey 4 , Thierry Baron 5 4 , Vincent Paillard 1 Show Abstract
1 , CEMES-CNRS, Toulouse France, 2 , Université Bourgogne-Franche Comté, Dijon France, 3 , LAAS CNRS, Toulouse France, 4 , CEA, Grenoble France, 5 , Université Grenoble Alpes, Grenoble France
In 1983, M. Kerker et al. predicted pure forward and pure backward visible light scattering by hypothetical magneto-dielectric particles, occurring under the so-called Kerker conditions . Even though the magnetic permeability is unitary in dielectric media, high-index dielectric particles allow to simultaneously obtain strong electric and magnetic resonances . Interference of such electric and magnetic modes can then allow to de-facto fulfill the Kerker conditions, leading to strongly directional scattering under specific conditions. Only recently, such uni-directional visible light scattering has been experimentally demonstrated with dielectric nanoparticles [2-3].
We show theoretically and experimentally that strongly anisotropic scattering also occurs in single silicon cylindrical nanowires. We demonstrate that this directionality can be controlled in a first step via the nanowire diameter. The linear polarization angle of the incident light offers an additional degree of freedom compared to spherical nanoparticles. Perpendicular or parallel polarization with respect to the nanowire axis allows to excite either pure electric or pure magnetic modes, respectively. However, strong intense electric and magnetic fields still occur simultaneously in each case, arising from modes of different high orders. Only very small nanowire, supporting a single nondegenerate TM mode, induce an omnidirectional light scattering .
We also investigate silicon nanowires fabricated via electron beam lithography of silicon on quartz (SOQ) substrates. The fabrication of structures on SOQ substrate allows us to study systematically the optical response of single crystal silicon nano-structures of precisely defined geometry. We find that the forward to backward scattering ratio can be engineered not only by the size but also via the asymmetry ratio of nanowires of rectangular cross-section. Fano-like resonances arising for specific wavelengths and geometry parameters strongly modify the forward/backward ratio compared to nanowires of symmetric cross-section.
In conclusion, we show that the direction of visible light scattering by dielectric nanowires can be tuned as function of their shape and dimensions, and that it can be further controlled via the polarization of the incident light.
 Kerker, M., Wang, D.-S. & Giles, C. L. Electromagnetic scattering by magnetic spheres. Journal of the Optical Society of America 73, 765 (1983).
 Kuznetsov, A. I., Miroshnichenko, A. E., Brongersma, M. L., Kivshar, Y. S. & Luk’yanchuk, B. Optically resonant dielectric nanostructures.
Science 354, aag2472 (2016).
 Person, S. et al. Demonstration of Zero Optical Backscattering from Single Nanoparticles. Nano Letters 13, 1806–1809 (2013).
 Wiecha, P. R. et al. Strongly Directional Scattering from Dielectric Nanowires. ACS Photonics 4, 2036–2046 (2017).
8:00 PM - EM03.13.17
Developing New Nanostructures for Biosensors in Disease Detection through Surface-Enhanced Raman Spectroscopy (SERS)
Shantanu Aggarwal 1 , Prajith Karadan 2 , Chandrabhas Narayana 1 , Harish Barshilia 2 Show Abstract
1 Chemistry and Physics of Materials Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, Karnatak, India, 2 Surface Engineering Division, CSIR-National Aerospace Laboratories, Bangalore, Karnataka, India
Raman spectroscopy is a method of determining modes of molecular vibrations. It gives information about molecular structure and is an excellent tool to study excitations in molecules. But Raman scattering is a very weak process and to overcome this, surface enhanced Raman scattering (SERS) is used. In SERS, the scattering cross section of a molecule is increased by adsorbing it on the surface of a noble metal, having nanoscale roughness. Raman signals are enhanced by a factor of 106 – 108. Recent advances in the field of optical technology and nanofabrication have led to the development of new techniques using Raman spectroscopy. Surface-enhanced Raman scattering and Tip-enhanced Raman scattering are two such techniques. One of the foremost advantages of SERS is the rich blend of high sensitivity and chemical imaging capability, which vastly caters to the needs of ultra-trace analysis of molecules. Strategies for SERS detection can be optimised by harnessing the electromagnetic and chemical enhancement mechanisms of SERS.
We have reported a skeleton key platform for surface-enhanced Raman spectroscopy (SERS) based biosensor, utilising ordered arrays of Si nanopillars (SiNPLs) with plasmonic silver nanoparticles (AgNPs). The optimised SiNPLs based SERS (SiNPLs-SERS) sensor exhibited high enhancement factor (EF) of 2.4*10 8 for thiophenol with sensitivity down to 10 -13 M of R6G molecules. The ordered array of SiNPLs stabilises the distribution of AgNPs along with the light trapping properties, which resulted in high EF and excellent reproducibility. The uniformity in the arrangement of AgNPs makes a single SiNPLs-SERS substrate to work for all types of biomolecules such as positively and negatively charged proteins, hydrophobic proteins, cells and dyes, etc. The experiments conducted on differently charged proteins, amyloid beta (the protein responsible for Alzheimer's), E-coli cells, healthy and malaria-infected RBCs provide a proof of concept for employing the universal SiNPLs-SERS substrate for trace biomolecule detection. These sensors have high sensitivity and can be used to probe biomolecules likes proteins, DNA, peptides, drugs etc. by SERS. Detection of malaria at early stages have always been a major challenge and our SERS-based biosensor can help in detection of malaria, cancer and other diseases at very early stages, when the proteins are present in very small concentrations, due to its high sensitivity. We have tried to study the surface proteins in healthy RBCs as well as those infected with malaria. The SERS spectrum of the two cases is entirely different due to the presence of new surface proteins on RBCs when they are infected with Malaria. This Si- nanopillar SERS sensor can be used in multi-wavelength for detection: 405 nm, 532 nm, 633 nm and 785 nm. The FDTD simulations substantiate the superior performance of the sensor achieved by the tremendous increase in the hotspot distribution compared to the bare Si sensor.
8:00 PM - EM03.13.18
Spectral Gaps and Resonant States of Prime-Based Aperiodic Arrays
Ren Wang 1 , Felipe Pinheiro 2 , Luca Dal Negro 1 Show Abstract
1 , Boston University, Boston, Massachusetts, United States, 2 Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro Brazil
In this presentation, we address the relationships between spectral and structural properties in a number of representative systems with periodic, random, quasi-periodic and deterministic aperiodic geometry using the rigorous Green’s matrix method, which provides access to scattering resonances and spectral statistics of large-scale deterministic systems. In particular, we apply interdisciplinary methods of spatial point pattern analysis and spectral graph theory to gain information on the characteristic geometrical and connectivity properties of deterministic aperiodic arrays that determine their distinctive resonant scattering behavior. Based on this knowledge, we show how it is possible to predict general features of their spectra and scattering resonances including edge-localized modes that appear in the energy gap regions. This work, which is primarily concerned with the fundamental structure-property relationships in deterministic aperiodic systems, unveils the importance of spectral geometry and spectral graph methods for the engineering of nanoparticle arrays with various degrees of aperiodic order and uniformity.
8:00 PM - EM03.13.19
Free-Space Optical Beam Tapping with an All-Silica Metasurface
Qitong Li 1 2 , Fengliang Dong 3 , Bo Wang 2 , Weiguo Chu 3 , Qihuang Gong 2 , Yan Li 2 , Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States, 2 , Peking University, Beijing China, 3 , National Center for Nanoscience and Technology, Beijing China
Extraction of information about the multi-dimensional optical properties of free-space and guided optical beams is critical in modern photonics. To date, planar, most beam-information detection systems destroy or substantially modify the original wave fronts of an incident beam in the detection process. Here, we demonstrate all-silica beam information detection system that effectively taps into a free space optical beam while leaving the original wavefronts virtually unaffected. This is accomplished by diverting a small (few percent) fraction of the light through the interaction with a silica metasurface based on the Pancharatnam-Berry phase. A chiroptical spectrometer and a multi-channel angular momentum detector are proposed to demonstrate the multifunctionality of this design principle. The concept and device proposed here may pave the way to in-situ beam monitoring and may provide a novel method to collect optical information for emerging augmented reality technologies.
Stephanie Law, University of Delaware
Viktoriia Babicheva, ITMO University
Svetlana Boriskina, Massachusetts Institute of Technology
Frank Neubrech, University of Heidelberg
EM03.14: Nitride-Based and High-Temperature Alternative Plasmonic Materials
Thursday AM, November 30, 2017
Hynes, Level 1, Room 104
8:15 AM - *EM03.14.01
Replacing Metals with Alternative Materials for Mid-IR to THz Plasmonics and Metamaterials—Does It Make Sense?
Jacob Khurgin 1 Show Abstract
1 Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, United States
Metals, which dominate the fields of plasmonics and metamaterials suffer from large ohmic losses which tends to dampen the lofty promise of nanoplasmonics and metamaterials. Therefore it would be greatly beneficial to identify alternative materials with smaller loss that have negative real part of dielectric constant and can potentially replace the metals
New plasmonic materials, such as highly doped semiconductors including oxides and nitrides, have smaller material loss combined with the negative epsilon in the IR range, and using them in place of metals carries a promise of reduced-loss plasmonic and metamaterial structures, with sharper resonances and higher field concentration. This promise is put to a rigorous analytical test in this work and it is revealed that having low material loss is not sufficient to have a reduced modal loss in plasmonic structures, unless the plasma frequency is significantly higher than the operational frequency. Using examples of nanoparticle plasmons and gap plasmons one comes to the conclusion that even in the mid-infrared spectrum metals continue to hold advantage over the alternative media.
Aside from alterantive plasmonic materials in the mid and far infrared ranges of the spectrum there exists a viable alternative to metals – polar dielectrics and semiconductors in which dielectric permittivity (the real part) turns negative in the Reststrahlen region. This feature engenders the so-called surface phonon polaritons (SPhPs) capable of confining the field in a way akin to their plasmonic analogues, the SPPs. Since the damping rate of polar phonons is substantially less than that of free electrons, it is not unreasonable to expect that “phononic” devices may outperform their plasmonic counterparts. Yet a more rigorous analysis of the comparative merits of phononics and plasmonics reveals a more nuanced answer, namely that while phononic schemes do exhibit narrower resonances and can achieve a very high degree of energy concentration, most of the energy is contained in the form of lattice vibrations so that enhancement of the electric field, and hence the Purcell factor, is rather small compared to what can be achieved with metal nanoantennas. Still, the sheer narrowness of phononic resonances is expected to make phononics viable in applications where frequency selectivity is important.
Overall, for most of the application, such as waveguide propagation and antenna the metals outperform the alternative materials but The new materials may still find application niche where the high absorption loss is beneficial, e.g. in medicine and thermal photovoltaics.
8:45 AM - EM03.14.02
Conductive Nitrides—Growth Principles, Optical and Electronic Properties and Their Perspectives in Photonics and Plasmonics
Panos Patsalas 1 , Nikolaos Kalfagiannis 2 , Spyridon Kassavetis 1 , Gregory Abadias 3 , Dimitris Bellas 4 , Christina Lekka 4 , Elefterios Lidorikis 4 Show Abstract
1 , Aristotle University, Thessaloniki Greece, 2 , Nottingham Trent University, Nottingham United Kingdom, 3 , University of Poitiers, Poitiers France, 4 , University of Ioannina, Ioannina Greece
The nitrides of most of the the group IVb-Vb-VIb transition metals (TiN, ZrN, HfN, VN, NbN, TaN, MoN, WN) constitute the unique category of conductive ceramics. Having substantial electronic conductivity and exceptionally high melting points, they were considered for a variety of electronic applications, which include diffusion barriers in metallizations of integrated circuits, ohmic contacts on compound semiconductors, and thin film resistors, since early eighties. Among them, TiN and ZrN are recently emerging as significant candidates for plasmonic applications. So the possible plasmonic activity of the rest of transition metal nitrides (TMN) emerges as an important open question. In this work, we review the experimental and computational (mostly ab initio) works in the literature dealing with the optical properties and electronic structure of TMN spanning over three decades of time and employing all the available growth techniques. We critically evaluate the optical properties of all TMN and we model their predicted plasmonic response. Hence, we provide a solid understanding of the intrinsic (e.g. the valence electron configuration of the constituent metal) and extrinsic (e.g. point defects and microstructure) factors that dictate the plasmonic response. We demonstrate that, indeed TiN and ZrN along with HfN are the most well-performing plasmonic materials in the visible range, while VN and NbN may be viable alternatives for plasmonic devices in the blue, violet and near UV ranges, albeit in expense of increased electronic loss. MoN and WN are disregarded as candidates for plasmonics, opposing recent theoretical works, due to the excessive concentration of point defects, even when in epitaxial form. Finally, TaN has a substantial plasmonic activity in the metastable, cubic rocksalt structure; however, in most cases it tends to form mixed cubic-hexagonal samples that are also excessively lossy. Furthermore, we consider the alloyed ternary TMN and by critical evaluation and comparison, we identify the emerging optimal tunable plasmonic conductors among the immense number of alloying combinations.
9:00 AM - EM03.14.03
Tunable Plasmonics from the UV to NIR with TiN-Based Ternary Nitrides
Spyridon Kassavetis 1 , Jean-Francois Pierson 2 , Dimitris Bellas 4 , Gregory Abadias 3 , Daniel Gall 5 , Elefterios Lidorikis 4 , Panos Patsalas 1 Show Abstract
1 , Aristotle University, Thessaloniki Greece, 2 , University of Lorraine, Nancy France, 4 , University of Ioannina, Ioannina Greece, 3 , University of Poitiers, Poitiers France, 5 , Rensselaer Polytechnic Institute, Troy, New York, United States
Conductive binary transition metal nitrides, such as TiN and ZrN, have emerged as a category of promising alternative plasmonic materials owing to their substantial electronic conductivity, refractory character and CMOS compatibility. However, due to their short intrinsic conduction electron mean free path, their spectral tunability by varying the size and/or the shape of nanostructures is quite limited. This limitation has been addressed recently by the introduction of ternary conductive nitrides as tunable plasmonic materials [Kassavetis et al, Appl. Phys. Letters 108, 263110 (2016); Metaxa et al, ACS Appl. Mater. Interfaces, 9, 10825 (2017)]. In this work, we show that ternary transition metal nitrides such as TixTa1-xN, TixZr1-xN, TixSc1-xN, TixAl1-xN, and TixMg1-xN in the B1 rocksalt structure share the important plasmonic features with their binary counterparts, while having the additional asset of the exceptional spectral tunability in the entire visible (400–700 nm) Near Infrared (NIR, 700-1350 nm) and UVA (315–400 nm) spectral ranges depending on their net valence electrons per unit cell; thus, TixTa1-xN is recommended for plasmonic devices in blue, violet and UV, TixAl1-xN for deep red, and TixSc1-xN and TixMg1-xN for NIR. In particular, we demonstrate that nanoparticles of such ternary nitrides can exhibit maximum field enhancement factors inferior but comparable with gold in the aforementioned broadband range (315-1350 nm). These nitrides exhibit substantial electronic losses mostly due to fine crystalline grains that deteriorate the plasmonic field enhancement. Thus, we critically compare the plasmonic performance of epitaxial and polycrystalline ternary nitrides, we evaluate the structural features that affect the quality factor of the plasmon resonance, and we provide rules of thumb for the selection and growth of materials for nitride plasmonics.
9:15 AM - EM03.14.04
Tunable Double Epsilon-Near-Zero Behaviour in Titanium Oxynitride Thin Films
Matthew Wells 1 , Hannah Hill 1 , Ryan Bower 1 , Brock Doiron 1 , Bin Zou 1 , Andrei Mihai 1 , Peter Petrov 1 Show Abstract
1 , Imperial College London, London United Kingdom
Owing to its superior thermal stability and compatibility with silicon-based electronics, Titanium Nitride has often been proposed as a promising alternative to gold for plasmonic applications. Here, the effects of varying the oxygen partial pressure during the reactive magnetron sputtering of titanium nitride thin films are studied. We find that, while samples fabricated with a residual oxygen pressure of less than 5E-9 Torr exhibit metallic behaviour with a single epsilon-near-zero (ENZ) frequency in the region of 500 nm; samples deposited with a level of residual oxygen between 5E-9 and 2E-8 Torr exhibit double ENZ behaviour and are of TiOxNy composition. In this case, the two ENZ wavelengths are tunable between 700-850 nm and 1100-1350 nm according to the partial pressure of nitrogen during the deposition process. Meanwhile, samples deposited under a greater oxygen content exhibit dielectric behaviour.
Using the Maxwell-Garnet theory for the optical properties of a composite film, the observed double ENZ behaviour of the TiOxNy samples is shown to arise from inclusions of TiN within a TiO2 matrix. This behaviour was observed for amorphous TiOxNy films deposited on both MgO and Si substrates, thereby allowing the potential fabrication of novel devices with tunable plasmonic behaviour, compatible with CMOS technology.
9:30 AM - EM03.14.05
Multiphase Strontium Molybdate Thin Films for High Temperature Plasmonic Applications
Matthew Wells 1 , Mohammad Rais Taufiq 1 , Yifan Zhao 1 , Yiming Lin 1 , Brock Doiron 1 , Rebecca Kilmurray 1 , Bin Zou 1 , Andrei Mihai 1 , Peter Petrov 1 Show Abstract
1 , Imperial College London, London United Kingdom
Strontium molybdate (SrMoO3) has recently been proposed as a promising alternative plasmonic material, owing to a high degree of performance tunability together with relatively low optical losses. However, to facilitate the realisation of SrMoO3 -based plasmonic devices, the material’s propensity to oxidation, particularly when exposed to elevated temperatures, must be suppressed.
In this work, we report a method to improve the high temperature stability of SrMoO3 thin films. We show that, after treatment of the samples, an additional crystalline phase of strontium molybdate (SrMoO4) is formed. Following characterisation of these samples by means of XRD, AFM, and spectroscopic ellipsometry, this additional phase is found to result in a change of microstructure in the film as well as significantly reduced optical losses. Moreover, following ex-situ annealing in air, it is found that the additional SrMoO4 phase acts to suppress the further oxidation of the samples, with thermal stability maintained up to approximately 500 °C as opposed to 300 °C for the samples without treatment. However, the temperature of 500 °C should not be considered an upper limit.
9:45 AM - EM03.14.06
High Temperature Plasmonic Materials and Applications
Urcan Guler 1 , Harsha Reddy 1 , K. Chaudhuri 1 , Alexander Kildishev 1 , Alexandra Boltasseva 1 , Vladimir Shalaev 1 Show Abstract
1 , Purdue University, West Lafayette, Indiana, United States
The enhanced interaction of subwavelength plasmonic nanostructures with electromagnetic waves in the visible and infrared windows can significantly improve devices in a variety of application areas. Harsh-environment applications, and more specifically high temperature applications, represent one important avenue where plasmonics can make a difference. However, problems associated with nanoscale metallic materials at high temperatures are the roadblocks in realization of reliable nanophotonic components in these applications. Transition metal nitrides show plasmonic properties in the visible and near-infrared ranges with refractory properties and promise solutions to durability challenges in harsh environmental applications. In this talk, we will present our recent results on plasmonic material systems for high temperature applications. Temperature dependent optical properties of plasmonic materials are studied experimentally with an in situ spectroscopic ellipsometer and the optical properties at high temperatures up to 1000 oC are utilized for accurate design of plasmonic components. We show that single crystalline epitaxial silver and gold films have significantly higher durability at elevated temperatures when compared to polycrystalline thin films. In addition, titanium nitride can withstand substantially higher temperatures and retains its optical properties. Zirconium nitride thin films with improved plasmonic properties are developed and characterized for applications in the visible and near-infrared. With lower optical losses compared to widely studied titanium nitride, zirconium nitride can be the refractory plasmonic material of choice for some harsh-environment applications where losses are of primary importance. We also study alternative fabrication routes for refractory plasmonic materials for large-scale nanoarchitectures. Utilizing nitridation of oxides under ammonia flow, we show that plasmonic titanium nitride can be obtained from titanium dioxide samples with complex structures.
EM03.15: Low-Dimensional Materials
Thursday PM, November 30, 2017
Hynes, Level 1, Room 104
10:30 AM - *EM03.15.01
Ballistic Surface Plasmons in High Mobility Dirac Liquid of Graphene
Dmitri Basov 1 , Guangxin Ni 1 Show Abstract
1 , Columbia University, New York, New York, United States
Optical spectroscopies are an invaluable resource for exploring new physic of new quantum materials. Surface plasmon polaritons and other forms of hybrid light-matter polaritons provide new opportunities for advancing this line of inquiry. In particular, polaritonic images obtained with modern nano-infrared tools grant us access into regions of the dispersion relations of various excitations beyond what is attainable with conventional optics. I will discuss this emerging direction of research with two examples from graphene physics: i) ultrafast dynamics of hot photo-excited electrons ; and ii) ballistic electronic transport at low temperatures .
 D.N. Basov, M.M. Fogler and F. J. Garcia de Abajo “Polaritons in van der Waals materials”, Science 354, 195 (2016).
 G. X. Ni, L. Wang, M. D. Goldflam, M. Wagner, Z. Fei, A. S. McLeod, M. K. Liu, F.Keilmann, B. Özyilmaz, A. H. Castro Neto, J. Hone, M. M. Fogler and D. N. Basov Nature Photonics 10, 244 (2016)
 G. X. Ni, A. S. McLeod, L. Xiong et al. [in preparation].
11:00 AM - EM03.15.02
From Unidirectional Invisibility to Nonreciprocity in Nonlinear PT-Symmetric Plasmonic Metamaterials
David Barton 1 , Mark Lawrence 1 , Hadiseh Alaeian 2 , Jennifer Dionne 1 Show Abstract
1 Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 Physics, Northwestern University, Evanston, Illinois, United States
Non-reciprocal transmission of light is essential for a variety of optics and communications applications, ranging from optical isolators and diodes to active camouflage, cloaking, and nonreciprocal lensing. Achieving non-reciprocal transmission requires a departure from linear and time invariant materials, ordinarily accomplished either with bulky components, micron-scale optical path lengths, and/or high-quality-factor resonances that limit the spectral range. Here, we investigate a thin film material exhibiting nonreciprocity over a large wavelength and angular spectrum. In particular, we consider a nonlinear, non-Hermitian plasmonic metamaterial with a 150 nm unit cell composed of five alternating layers of Silver and a high index dielectric (n=3.2). The structure is made non-Hermitian and parity-time symmetric by inclusion of loss or gain in alternating dielectric layers. Analytical calculations reveal a bandstructure and band gap tunable with the amount of loss and gain. In the linear regime, the structure exhibits unity transmission at a wavelength of 500 nm near the optical band gap; further, internal electric field intensities vary based on the illumination direction (i.e., illumination from the “loss” or “gain” side of the metamaterial) by up to an order of magnitude, and zero reflection occurs in only one direction. To make this metamaterial nonreciprocal, saturable absorption is included in the loss dielectric layers. This nonlinearity allows for intensity-based increase of the bandgap such that illumination from the loss side is in the band gap, but is in the band pass from the gain side. In this way, we can use the bandstructure to tune transmission. Full field finite element simulations reveal nonreciprocal transmission with a transmission difference greater than 10 dB within three free space wavelengths. This system also exhibits a nonreciprocal response over a 65nm spectral range (limited by the bandgap of the linear material) and over 60 degrees of illumination direction. By homogenizing this plasmonic metamaterial and extracting the effective direction-dependent impedance and index, we show that this material acts as an artificial Kerr metamaterial. Our material represents a novel route toward broad-angle and broad-wavelength nonreciprocity in thin films, providing a foundation for new one-way optical materials and functionalities.
11:15 AM - EM03.15.03
Strong Modulation of the Amplitude and Phase of Optical Spatial Coherence
Dongfang Li 1 , Domenico Pacifici 1 Show Abstract
1 , Brown University, Providence, Rhode Island, United States
The degree of optical spatial coherence is a fundamental property of light that describes the mutual correlations between fluctuating electromagnetic fields. It plays an essential role in varieties of applications from beam shaping and high-resolution biological imaging to photovoltaics and optical biosensors. However, full control of spatial coherence at length scales comparable to the wavelength of light has proven challenging. Although it has theoretically been suggested that surface plasmon polaritons (SPPs)— electromagnetic waves evanescently bound to metal surfaces—can in principle modulate the degree of spatial coherence, a very few experimental studies have shown this effect, reporting only modest modulation.
Here we employ SPPs as a means to mix the random fluctuations of the incident electromagnetic fields at the slit locations of a Young’s double-slit interferometer. Strong tunability of the complex degree of spatial coherence of light is achieved by optimizing the slit parameters and finely varying the separation distance between the two slits. Continuous modulation of the degree of spatial coherence with amplitudes ranging from 0% up to 80% allows us, for the first time, to transform totally incoherent incident light into highly coherent light, and vice versa.  In contrast to SPPs excited by transverse magnetic illumination (TM), we experimentally demonstrate that both TM and TE (i.e., transverse electric) photonic modes in planar waveguides can also serve as channels to mix the fluctuating electromagnetic fields and strongly modulate the optical spatial coherence. This configuration can be realized without using any metallic materials, thus resulting in reduced optical loss and enhancement of the light transmission.
These findings can lead to alternative nano-engineered optical flat surfaces that leverage the degree of spatial coherence to achieve ultimate control of light flow, beyond conventional refractive- and diffractive-based photonic metasurfaces.
 D. Li and D. Pacifici. “Strong Amplitude and Phase Modulation of Optical Spatial Coherence with Surface Plasmon Polaritons.” arXiv.1612.09153, under review of Science Advances (2016)
11:30 AM - EM03.15.04
Plasmonics in Fractal Dimensions
Francesco De Nicola 1 Show Abstract
1 Graphene Labs, Istituto Italiano di Tecnologia, Genova Italy
Deterministic fractals1 are self-similar objects generated by geometrical rules. Typically, fractals have non-integer Hausdorff-Besicovitch dimension dH and exhibit non-discrete Fourier spectra. Recent efforts in employing fractal geometry in optoelectronics have led to novel metamaterial designs2. In particular, plasmonic fractals made of noble metals offer a potential platform for enhanced light-matter interactions and effective control over their optical properties by tailoring their size, shape, and position2. For instance, the multiscale property of fractals may be exploited to realize devices with a multimodal plasmonic spectral response and a hierarchical spatial distribution of the electrical near-field2. However, the finite thickness of such thin metallic structures hinders the study of proper fractal systems with 1H<2.
Two-dimensional materials, such as graphene, have been proven to be appealing platforms to investigate plasmonics in two- and one-dimensional systems3. Therefore, fractal 2D materials would provide an excellent mean to study plasmonics in real dH-dimensional systems. Notably, the charge carrier concentration-dependent optical conductivity of graphene allows for the control of the plasmon resonances by electrical field-effect gating in graphene-based optoelectronic devices. Furthermore, high-quality graphene tends to host charge carriers with a large room-temperature mobility, which usually leads to long plasmon lifetimes and low losses4.
Here, we present the fabrication, optical and electrical characterization, and numerical simulation of Sierpinski carpet (SC)1 deterministic fractals based on 2D materials. We fabricated graphene SCs by employing electron-beam lithography and reactive-ion etching techniques. By optical spectroscopy, we observed a multiband plasmonic response of the SC from the visible to the mid-infrared range, exhibiting a self-similar set of resonances, which can be electrically tuned. Also, by surface enhanced Raman spectroscopy the hierarchical spatial distribution of the fractal electrical near-field was investigated, thereby demonstrating an immediate application of the SC for molecular sensing.
Fractal plasmonics encompass a wide range of optoelectronic applications2 and beyond its fundamental physics understanding, our purpose is to investigate novel architectures for nanoscale photodetectors, solar cells, bio/chemical sensors, and lasers.
This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 696656-GrapheneCore1.
1 B. B. Mandelbrot, The fractal geometry of nature (W. H. Freeman, San Francisco, 1983).
2 L. Dal Negro and S. V. Boriskina, Laser Photonics Rev. 6, 178-218 (2012).
3 F. H. L. Koppens et al., Nano Lett. 11, 3370-3377 (2011).
4 A. N. Grigorenko et al., Nat. Photon. 6, 749-758 (2012).
11:45 AM - EM03.15.05
Mimicking Smith-Purcell Emission Manipulation in Optics
Lin Li 1 , Kan Yao 1 , Yongmin Liu 1 2 Show Abstract
1 Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States, 2 Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts, United States
The interaction of fast moving electrons with a material can generate electromagnetic radiation that is coherent to the evanescent field associated with the moving electrons. This effect is well known as electron-induced emission . The analysis of various interactions between electrons and materials is a substantial source of inspiration for advanced electron microscopy, including electron energy-loss spectroscopy, cathodoluminescence emission, Cherenkov radiation and Smith- Purcell emission, and so on. Recent breakthroughs in artificially engineered metamaterials and nanotechnology manifest new opportunities to tailor the interaction of the electron with matter, such as reversed or threshold-less Cherenkov radiation [2, 3]. However, up to date, much less work has discussed about the polarization control of electron-induced emission.
Recently, we proposed that the polarization state of Smith-Purcell emission can be effectively controlled with Babinet metasurfaces in the THz range . In this work, we successfully shift the working wavelength to the optical range. The polarization controlled light emission from an evanescent wave is demonstrated with both numerical simulations and experiments in the optical range, mimicking the manipulation of the Smith-Purcell emission.
In our experiment, we use the total internal reflection scheme to generate the evanescent wave by a prism, which is an analogue to the evanescent wave generated by moving electrons. Pragmatically designed C-aperture metasurfaces are excited by the evanescent wave and the re-emitted light is analyzed by a polarizer and a photon detector. An almost perfect polarization conversion ratio is achieved at the resonant frequency of the metasurface. Furthermore, when we change the orientation of the C-aperture, the polarization state of the emission is linearly polarized and the polarization direction is steered along the orientation of the C-aperture, which ensures the continuous manipulation of the polarization. The experimental results agree very well with the numerical simulations, revealing that the mechanism of the polarization control of the Smith- Purcell emission is due to the coupling between the evanescent wave and the intrinsic in-plane magnetic dipoles of C-aperture metasurfaces.
Our findings offer a versatile platform to extract and explore the near-field energy carried by relativistic charged particles and manifest promising applications in controlled free-electron light source and particle detectors. It will also further inspire studying the interaction between the charged particles and the artificial nanostructures in the future.
 F. J. Garcia de Abajo, Rev. Mod. Phys. 82, 209 (2010).
 S. Xi, et. al, Phys. Rev. Lett. 103, 194801 (2009).
 F. Liu, et. al, Nat. Photonics 11, 289 (2017).
 Z. Wang, et. al, Phys. Rev. Lett. 117, 157401 (2016).
EM03.16: Alternative Materials—MXenes and Metal Oxides
Thursday PM, November 30, 2017
Hynes, Level 1, Room 104
1:45 PM - *EM03.16.01
MXenes for Applications in Nanophotonics
K. Chaudhuri 1 , Zhuoxian Wang 1 , Mohamed Alhabeb 2 , Xiangeng Meng 1 , Shaimaa Azzam 1 , Alexander Kildishev 1 , Vladimir Shalaev 1 , Yury Gogotsi 2 , Alexandra Boltasseva 1 Show Abstract
1 , Purdue University, West Lafayette, Indiana, United States, 2 , Drexel University, Philadelphia, Pennsylvania, United States
MXenes are a large family of two-dimensional nanomaterials formed of transition metal carbides, nitrides and carbonitrides, many of which show high metallic conductivity, surface hydrophilicity and excellent mechanical properties. They are usually derived from layered ternary carbides and nitrides known as MAX (Mn+1AXn) phases by selective chemical etching of the ‘A’ layers and addition of surface functional groups ‘T’ (-O, -OH or -F), making the final composition of Mn+1XnTx. This study is motivated by the limited exploration of this new material class of growing interest, in the area of nanophotonics and plasmonics.
We present a random metamaterial constructed by dispersing monolayer Ti3C2Tx nano sheets into the gain medium for lasing application. Emission from the device under optical pump shows that sharp peaks start to emerge from the broad-band background at a threshold value of ~ 0.54 μJ/pulse. With increasing pump energy, other sharp peaks appear, which is consistent with the behavior of random lasing achieved through coherent feedback. The lasing behavior in this metamaterial can be controlled by changing the density of the Ti3C2 in solution. With increasing density of Ti3C2Tx, the optical response of the metamaterial is enhanced, thus making it easier to form lasing modes.
Localized surface plasmon type resonances (LSPR) have also been demonstrated in nanostructured films made from aqueous dispersion of 2D Ti3C2Tx nanosheets. A planar design of highly broadband plasmonic absorber is implemented as an application of this new plasmonic material. Aqueous dispersion of 2D sheets of MXene (with lateral dimension of 1-2μm) was spin coated and dried in nitrogen to form a continuous film on desired substrate. Using the measured optical data for these spin-coated films, we performed FEM simulations of Ti3C2Tx disks/pillar-like structures showing strong signatures of localized surface plasmon (LSP) type resonances in the NIR, tunable with varying dimensions. These resonances were then optimized for the design of the absorber with maximum efficiency in the NIR. This simple nano-disk array (diameter & thickness of 0.4 μm) enables ~80% absorption across ~0.5-1.6 μm. The spin coated films were patterned into disk arrays using electron beam lithography and dry plasma etching process and the absorption was experimentally measured using spectroscopic ellipsometry technique.
2:15 PM - EM03.16.02
MXene-Based Sensors for Surface-Enhanced Raman Spectroscopy
Asia Sarycheva 1 , Kathleen Maleski 1 , Taron Makaryan 1 , Yury Gogotsi 1 Show Abstract
1 , Drexel University Materials Science and Engineering Department, Philadelphia, Pennsylvania, United States
Recently, great interest has been demonstrated in developing ultrasensitive techniques for detecting low concentrations of molecules. One of the most promising techniques for monitoring chemical and biological processes and sensing a wide range of molecules is Surface Enhanced Raman Scattering (SERS)1, which is a non-invasive, fast, and highly sensitive and selective method based on surface plasmon resonance of metal nanostructures.
In our work, we have produced the first SERS substrate based on two-dimensional (2D) titanium carbide Ti3C2 (MXene). This recently emerging 2D material has already shown applicability in gas sensing2 and many other applications3. Additionally, Ti3C2 MXene has a visible to near-infrared plasmonic peak, making it a promising candidate for SERS.
Substrates have been fabricated using a simple, spray coating method with a colloidal solution of MXene flakes. Using this method, MXene island-like coverage was obtained with a high roughness, which allowed for visibility of “hot spots”. SERS performance was tested with diluted solution of Rhodamine 6G (10-7 mole/L) and reached an enhancement factor up to ~ 2x106. However, using an alternative dye, Acid Blue, which meets the resonant conditions but is known to adsorb less on the surface of MXene4, gave significantly less enhancement with EF = 2.7x103. This difference confirms the existence of the chemical enhancement of MXene.
This demonstration of the SERS effect opens new possibilities for using 2D metal carbides in plasmonics. The option of tuning plasmon resonance while using different MXenes, the biocompatibility, flexibility, and ease of fabrication makes MXene a good candidate for future development of SERS.
1. Kneipp, K., Wang, Y., Kneipp, H., Perelman, L. T., Itzkan, I., Dasari, R. R., & Feld, M. S. (1997). Single molecule detection using surface-enhanced Raman scattering (SERS). Physical review letters, 78(9), 1667.
2. Chen, J., Chen, K., Tong, D., Huang, Y., Zhang, J., Xue, J., ... & Chen, T. (2015). CO 2 and temperature dual responsive “Smart” MXene phases. Chemical Communications, 51(2), 314-317.
3. Anasori, B.; Lukatskaya, M. R.; Gogotsi, Y., 2D metal carbides and nitrides (MXenes) for energy storage. Nature Reviews Materials 2017, 2, 16098
4. Mashtalir, O., Cook, K. M., Mochalin, V. N., Crowe, M., Barsoum, M. W., & Gogotsi, Y. (2014). Dye adsorption and decomposition on two-dimensional titanium carbide in aqueous media. Journal of Materials Chemistry A, 2(35), 14334-14338.
2:30 PM - EM03.16.03
Dopant Incorporation in Cadmium Oxide for Plasmonic Applications
Thomas Beechem 1 , Evan Runnerstrom 2 , Anthony Mcdonald 1 , Jon-Paul Maria 2 , Jon Ihlefeld 1 Show Abstract
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 , North Carolina State University, Raleigh, North Carolina, United States
Possessing a differentiating combination of high carrier concentration and mobility, cadmium oxide (CdO) is being pursued as a high performance plasmonic material for the mid-infrared (MID-IR). Mobilities near 500 cm2/Vs at carrier concentrations greater than 5e19 cm-3 result in plasmonic figures of merit in the mid-IR comparable to that of gold in the visible. CdO thus has potential to impact a host of applications including thermography, heat-assisted magnetic recording, and waste-heat harvesting.
Accessing carrier concentrations of sufficient quantity to realize mid-IR plasmons while maintaining mobilities necessary to leverage them requires alternative means of doping. Traditionally, oxygen vacancies acting as an n-type dopant have been employed. This approach is problematic, however. The concentration of O-vacancies is difficult to control using oft employed reduction anneals. Additionally, oxygen tends towards double ionization. Double-ionization inherently increases impurity scattering and thus reduces mobility. To overcome these limitations, doping of CdO via dysprosium was shown to to simultaneously increase both carrier concentration and mobility. These dopants not only provide charge but also mollify the impact of oxygen vacancies on carrier transport. This study examines the physical phenomena belying this observation.
From a practical perspective, an optimized plasmonic response requires balancing dopant concentration, vacancy compensation and the concomitant changes that occur in both lattice stress and disorder. Monitoring these parameters is therefore vital for the continued improvement of this nascent material. Here, Raman spectroscopy is employed to these ends. Specifically, the relationship between carrier concentration, stress, disorder, and mobility for a series of Y-doped CdO films is measured from 80-300K with Raman spectroscopy. Practically, these relationships provide a high-throughput means to quantify mobility and carrier concentration via optical spectroscopy apart from Hall measurements. Scientifically, the results verify the paradigm of dopant incorporation postulated by Sachet et al.1 for conducting metal oxides in which defect equilibria can be leveraged to enhance both carrier concentration and mobility.
Sachet et al. Nat. Mat. (14) 414, 2015.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
2:45 PM - EM03.16.04
Realizing Bulk Metamaterials—Designed Optical Properties in Doped Cadmium Oxide Multilayer Films Free of Physical Interfaces or Lithography
Evan Runnerstrom 1 , Kyle Kelley 1 , Edward Sachet 1 , Christopher Shelton 1 , Jon-Paul Maria 1 Show Abstract
1 , North Carolina State University, Raleigh, North Carolina, United States
Transparent conductive oxides (TCOs) have emerged as a particularly attractive materials platform for plasmonics and metamaterials in the near- and mid-infrared (MIR). Among TCOs, doped cadmium oxide (CdO) exhibits exceptional electronic and plasmonic characteristics with tunable carrier concentration and high electron mobility, which enables low-loss plasmonic resonances. We have shown that through careful control of thin film growth and doping, doped CdO supports high quality plasmonic resonances across the entire MIR with tunable carrier concentrations spanning nearly two orders of magnitude (8x1019 to 4x1020 e-/cm3), accompanied by a maximum carrier mobility of over 500 cm2/V●s.
Here, we will show that through careful control over electron concentration, mobility, thickness, and film-substrate geometry, we are able to grow doped CdO films to target multiple plasmonic modes, including surface plasmon polaritons (SPP), epsilon-near-zero (ENZ) modes, and Brewster/Berreman modes. Additionally, by growing stacked doped/intrinsic/doped CdO layers with controlled thickness and separation, we are able to access additional SPP dispersion branches below the lightline resulting from coupling between the doped layers. Such control further allows us to grow multilayer CdO films with arbitrary layer thickness and doping: in a single stack, we achieve multiple (3+) absorption peaks associated with the ENZ mode of each individual layer. Additionally, these stacks display multiple thermal emission peaks, also associated with the ENZ mode frequency of each layer. As they require no lithography and contain no physical interfaces, these devices are, in effect, "bulk metamaterials." This discovery enables a simple and scalable method to engineer the optical properties of monolithic MIR metamaterials, ultimately opening the door to MIR absorption and emission by design.
EM03.17: Nanoparticle Networks
Thursday PM, November 30, 2017
Hynes, Level 1, Room 104
3:30 PM - *EM03.17.01
Seamless Integration of Metals, Dielectrics and III-V Semiconductors for Advanced Nanophotonic Devices
Seth Bank 1 Show Abstract
1 Microelectronics Research Center, University of Texas at Austin, Austin, Texas, United States
We review our progress towards the seamless epitaxial integration of III-V emitters/absorbers with several crystalline plasmonic materials (metals, semimetals, and doped semiconductors), as well as patterned high-contrast dielectric structures, for active plasmonic, metamaterial, and metasurface applications. We show that a variety of low-loss plasmonic and dielectric materials can be integrated into close proximity with high-efficiency III-V emitters, without degradation to their optical quality. This work was supported by AFOSR MURI FA9550-12-1-0488 and NSF-ECCS-1408302.
4:00 PM - EM03.17.02
Control of Collective Electric and Magnetic Resonances in Nanoparticle Lattices
Viktoriia Babicheva 1 , Andrey Evlyukhin 2 3 Show Abstract
1 , Georgia State University, Atlanta, Georgia, United States, 2 , Laser Zentrum Hannover e.V., Hannover Germany, 3 , ITMO University, St. Petersburg Russian Federation
Dipole coupling in one- and two-dimensional plasmonic nanoparticle arrays can produce narrow collective plasmon resonances in light transmission spectra, and the wavelengths are determined by the array periods. In the electric dipole approximation, the collective resonances (excitation of lattice waves) involves only dipole moments of the nanoparticles oriented perpendicular to the lattice wave propagation.
In this work, we theoretically study properties of a periodic array of plasmonic nanoparticles with different substrate and superstrate indices in parallel polarization. These plasmonic nanoparticles support only electric resonances, namely electric dipole and quadrupole resonances . Being spectrally overlapped with Rayleigh anomaly, these electric resonances give rise to pronounced lattice resonances. We performed rigorous numerical calculations, varied contributions of the electric dipole and quadrupole moments by changing particle size and shape (spheres and disks), and concluded that excitation of quadrupoles is critical for obtaining resonance features. We found that owing to excitation of collective quadrupole resonance, a narrow transparency band can appear between two Rayleigh’s anomalies which correspond to disappearing of the reflection and transmission first diffraction orders in case of different indices of substrate and superstrate.
In another case – when excitation of magnetic multipoles is possible, e.g. in high-index dielectric nanoparticles, – the lattice resonances appear in both perpendicular and parallel polarizations even for the dipole approximation . We have shown for the first time that, adjusting lattice periods independently in each mutual-perpendicular direction, it is possible to achieve a full overlap between the electric dipole lattice resonance and magnetic dipole resonance of nanoparticles in certain spectral range and to realize the resonant lattice Kerker effect (resonant suppression of the backward scattering or reflection). At the effect conditions, the strong suppression of light reflectance in the structure is appeared due to destructive interference between electromagnetic waves scattered by electric and magnetic dipole moments of every nanoparticle .
 A.B. Evlyukhin, C. Reinhardt, U. Zywietz, and B. Chichkov, "Collective resonances in metal nanoparticle arrays with dipole-quadrupole interactions," Phys. Rev. B 85, 245411 (2012).
 A.B. Evlyukhin, C. Reinhardt, A. Seidel, B.S. Luk’yanchuk, and B.N. Chichkov, "Optical response features of Si-nanoparticle arrays," Phys. Rev. B 82, 045404 (2010).
 A.B. Evlyukhin, V.E. Babicheva, “Resonant lattice Kerker effect in metasurfaces with electric and magnetic optical responses,” https://arxiv.org/abs/1705.05533
4:15 PM - EM03.17.03
Pure and Scalable Three-Dimensional Metallic Networks
Adi Salomon 1 , Racheli Ron 1 Show Abstract
1 , Bar-Ilan University, Ramat Gan Israel
Nanoporous metals are artificial and therefore their properties are a direct result of the preparation strategy. Practically, all the current available preparation techniques are multistep, and the resulting nanoporous metal contains foreign additives which eventually govern their optoelectronic properties and may deteriorate their performance. The inner architecture of nanoporous metals consists of random sizes and shapes of both particles and holes. Consequently, these metallic architectures are able to interact with the entire solar spectrum through excitation of surface plasmons (SPs), a collective oscillation of the metal’s free electrons. In a context of photo-catalysis, metallic nanostructures with a characteristic length smaller than 30 nm are important because of the high probability to excite charge carriers upon SPs decay. Herein, we demonstrate a simple scalable method to fabricate pure 3D metallic networks of nano-size building-blocks. Our strategy is based on physical vapor deposition (PVD) on a silica aerogel substrate which initiates self-organization of the vapored metallic atoms into a nanoporous network. The inner architecture of these disordered metallic networks is made of particlulated ligaments, size at tens of nanometers, and multimodal nanoscale pore sizes. The silica aerogel substrate, the metal type, and the PVD parameters all play a role in determining the geometrical parameters of the network. The resulting networks have distinct colors, different from the corresponding bulks, depending on the type of metal and the network thickness. The large-scale networks are transparent, flexible, pure, and show indication for hot carriers generation and photo-catalytic activity upon white-light illumination.
(1) Ron, R.; Gachet, D.; Rechav, K.; Salomon, A. Direct Fabrication of 3D Metallic Networks and Their Performance. Adv. Mater. 2016, 1604018--n/a.
4:30 PM - EM03.17.04
Localized Optical Phenomena in Network Metamaterials and 2D Heterostructures
Linn Bieske 1 2 , Kundan Chaudhary 1 , Michele Tamagnone 1 , Cigdem Keskinbora 1 , Henning Galinski 2 , Antonio Ambrosio 3 , David Bell 1 3 , Ralph Spolenak 2 , Federico Capasso 1 Show Abstract
1 Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Zurich, Zurich, Switzerland, 3 Center for Nanoscale Systems, Harvard University, Cambridge, Massachusetts, United States
Optical metamaterials gained interest as a platform to achieve control of light on a subwavelength scale. The traditional design of metamaterials typically relies on a periodic arrangement of optical elements. However recently, a new class of optical materials based on subwavelength disordered metallic network has been theoretically described, fabricated, and experimentally investigated [1,2]. Due to the high connectivity, the optical properties of such network metamaterials are extremely robust and controllable on a large scale.
Here, we will discuss the local optical responses of network metamaterials in the vicinity of two dimensional materials, such as graphene and hexagonal boron nitride. The investigated network metamaterial consists of a dealloyed copper aluminum thin film forming a randomly disordered porous network of nano-resonators and micro-cavities characterized by a wide range of sizes. A chemical wet process is used to dealloy aluminum and create the copper network.
Using a variety of near field scanning optical microscopy (NSOM) techniques optical near-field phenomena such as the coupling of the surface guided modes with the nanopores are investigated. Experiments employing reflectance measurements, scanning optical near field microscopy, Raman spectroscopy and other techniques are used to investigate several optical phenomena in a broad frequency range from mid infrared up to ultraviolet.
Furthermore, we will discuss our ongoing efforts to use these composite metamaterials as versatile platform to engineer new passive and active metamaterials.
 H. Galinski, et al: Light manipulation in metallic nanowire networks with functional connectivity. Adv. Optical Matererials (2017) 5, 1600580;
 H. Galinski, et al: Scalable, ultra-resistant structural colors based on network metamaterials. Light: Science & Applications (2017) 6, e16233;
EM03.18: Poster Session II: Alternative Plasmonic Materials and Fabrication Methods
Friday AM, December 01, 2017
Hynes, Level 1, Hall B
8:00 PM - EM03.18.01
Demonstration of Multilayer Strategy to Enable Full Color Reproduction for Plasmonic Printing
Zheng Jie Tan 1 , Nicholas Fang 1 Show Abstract
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
We demonstrate the use of geometrical design parameters on combined dielectric and metal layers for generating arbitrary colors in planar devices. Such a coloring strategy is advantageous over the use of traditional pigments as it will enable functional photocatalytic materials to have a tailored optical response. We fabricated a material stack, designed with the aid of a random search algorithm, and showed that it is able to span the entire optical spectrum by varying the thickness of just one particular layer within the stack by 50nm. This can lead to full color plasmonic printing at micron resolutions using raster dot masks but without expensive alignment techniques.
8:00 PM - EM03.18.02
Exploring Plasmonic Environment with Electrochromic Polymer
Mohammad Shahabuddin 1 , Thomas McDowell 1 , Natalia Noginova 1 Show Abstract
1 , Norfolk State University, Norfolk, Virginia, United States
Charge transfer processes can be significantly modified in plasmonic environment, resulting particularly, in alteration of electrochromic polymer absorption spectra and color switching dynamics. In order to better understand the origin of these effects, we study optical behavior of thin polyaniline films deposited on various gold flat and nanostructured substrates as the function of the applied voltage. The effect of the potential difference on the optical properties of polyaniline is observed in uv-vis reflection spectra and found to be significantly different in the films deposited on flat gold and gold fishnet structures. Films on nanostructured gold demonstrate much sharper response to electrode potential and faster saturation with increase in voltage than those on flat gold. Illumination at the wavelength of plasmon resonance can provide an additional opportunity for control of the color switching process. The effects are discussed in terms of plasmogalvanic effects and hot electron emission.
8:00 PM - EM03.18.03
Plasmonic Gratings on PDMS Substrates
Joel Loh 1 Show Abstract
1 Electrical Engineering, University of Toronto, Toronto, Ontario, Canada
While metallic gratings and nanoparticle arrays that exhibit strong plasmonic absorption in the visible is relatively common and facile to fabricate, the substrates they are deposited on are typically inflexible and do not allow mechanical modulation of the absorption spectrum.
In this study we imprinted 50nm diameter polystyrene beads on an PDMS mold and left periodic arrays of cups, which we then sputter deposited the PDMS with 40nm layer of silver. The resulting PDMS mold exhibit a strong gold color, and show strong broad absorption in the visible; furthermore, inherent flaws in the silver film also exhibit absorption peaks in the near and far IR. With this flexible PDMS substrate we are able to modulate the peak intensities of both the visible and IR peaks. The visible regime peak decreases in intensities while the IR peaks increase in intensities under stretching of the PDMS substrate. We are also able to imprint 25nm diameter polystyrene beads on PDMS which generates a red color. Thus, a combination of polystyrene beads with different diameters will allow a variable grating to be imprinted on PDMS. This will have applications in the sensing field, since a hyper-spectrum sweep can be conducted on a single substrate.
8:00 PM - EM03.18.04
Various Dye-Doped Polymer Thin Films for Spaser Devices
Peter Tananaev 1 , Aleksei Komarov 1 , Georgiy Yankovskii 1 , Alexander Baryshev 1 Show Abstract
1 , FSUE VNIIA, Moscow Russian Federation
Robust plasmonic devices should take into account the material properties of metal constituent elements limiting plasmonic wave propagation length because of losses. It is expected that the concept of active plasmonics can compensate intrinsic-to-metal losses by introducing the gain media. Fluorescent dyes (or quantum dots) in liquid or polymer matrices are proposed for the spaser device [1,2].
In our work, we have fabricated a series of dye-doped polymer (PMMA, PVA, Su8) thin films based on Rhodamine 101 dye (R101) by using spin-coating. The films have been characterized for dye aggregation by different means, including fluorescence lifetime imaging. The optical gain of the films has been defined via detection of the amplified stimulated emission (ASE) signal measured in accordance to the variable stripe length method . Pulsed radiation of 532 nm with a duration of 10 ns, a repetition rate of 10 Hz and energy densities of 10–100 kW/cm2 allowed to observe a threshold in ASE signal from the films and narrowing of the fluorescence line width. Typical gain of 10–20 cm-1 was achieved for the fabricated dye-doped polymer films. Dependence of ASE on the film thickness, the type of polymer and presence of metal sublayer will be discussed.
The best R101-doped PVA film having an optimal thickness have been deposited onto 2D silver-based spaser structures analogous to those reported in Ref.  and studied in detail. We speculate that the optical gain of 20 cm-1 and a lateral dimension of 500x500 µm are not enough for observing desired lasing effects.
 A. Yang, T.B. Hoang, M. Dridi, C. Deeb, M.H. Mikkelsen, G.C. Schatz, T.W. Odom. Real-time tunable lasing from plasmonic nanocavity arrays. Nature Comm. 6:6939 (2015)
 X.Meng, J.Liu, A.V. Kildishev, V.M. Shalaev. Highly directional spaser array for the red wavelength region. Laser & Photonics Reviews, 8: 896–903 (2014)
 K. L. Shaklee and L. F. Leheny. Direct determination of optical gain in semiconductor crystals. Appl. Phys. Lett. 18, 475 (1971)
8:00 PM - EM03.18.05
Soft Matter Plasmonics—Accessing the IR Window with PEDOT:PSS—A Computational Approach
Nikolaos Kalfagiannis 1 , Dimitris Bellas 2 Show Abstract
1 , Nottingham Trent University, Nottingham United Kingdom, 2 , University of Ioannina, Ioannina, Ioannina, Greece
Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is one of the most well-established conductive polymers in terms of practical applications. It possesses many unique characteristics, such as excellent film formation ability in a variety of substrates by various scalable fabrication schemes, superior optical transparency in the visible spectral range, high electrical conductivity, intrinsically high work function and good physical and chemical stability in air. It has a wide range of applications in energy storage and energy conversion devices, in micro-fluidics and in displays and lighting to name a few. Despite its extreme conductivity, its application in plasmonics has been underestimated or not even foreseen, to certain extend.
In this work, the prospects of printed PEDOT:PSS in plasmonics are investigated. At first, we compare its optical properties with the optical properties of other prominent alternative plasmonic materials, such as Al doped ZnO, Indium-Tin-Oxide, Titanium Nitride as well as with those of conventional metals such as Gold and Silver. We demonstrate that PEDOT:PSS features a permittivity, whose real part is negative at sufficiently long wavelengths, a condition for supporting surface plasmon polaritons. The fundamental properties of PEDOT:PSS and its dielectric function spectra for various PEDOT:PSS formulations are evaluated in this work and an initial screening of material processing parameters is established, in an effort to show that such considerations can impact the entire technological field of nanoplasmonics and metamaterials.
Following that, the potential plasmonic performance of PEDOT:PSS is assessed by calculating: i) the Localised Surface Plasmon Resonance (LSPR) traits (enhanced electric fields and scattering) of various shaped PEDOT:PSS nanostructures utilizing the Finite-Difference Time-Domain (FDTD) method. We explore the modulation of LSPR depending on the shape and size of PEDOT:PSS structures, based on the feature sizes of various printing techniques, and the local structure and ii) the dispersion of SPPs in various PEDOT:PSS/dielectric (Air, Germanium, Silicon, c-diamond, Diamond-Like Carbon) planar interfaces. Our calculations suggest that PEDOT:PSS can be used as a material with sufficient mode confinement in the technologically important infrared regime.
8:00 PM - EM03.18.06
Plasmonic Photoconductive Antennas Based on a Multilayer GaAs: Si/i-LT-GaAs Heterostructure Grown on GaAs with Orientations of (100) and (111) A
Arsenii Buriakov 1 , Elena Mishina 1 , Vladislav Bilyk 1 , Galib Galiev 2 , Dinar Husyainov 1 , Sergey Pushkarev 2 , Petr Maltsev 2 Show Abstract
1 , Moscow Technological University (MIREA), Moscow Russian Federation, 2 , Institute of Ultra High Frequency Semiconductor Electronics RAS, Moscow Russian Federation
Over the past two decades the terahertz frequency band of electromagnetic radiation (0.1-10 THz) has been actively studied. Spectroscopy in this range of wavelengths has many applications. In particular, terahertz spectroscopy of organic substances makes it possible to investigate conformational modifications of complex molecules and to distinguish between structural isomers.
Multilayer films based on LT-GaAs were investigated. The traditional approach is that the LT-GaAs film is doped with beryllium atoms, which are acceptors. Electrons from the energy levels of the anti-structural defects "atom As at the site of atom Ga" pass to acceptor levels, and the anti-structural defects become ionized and function as electron traps, reducing their lifetime. In our samples the following approach was used: in LT-GaAs films grown on GaAs (100) and (111) A substrates, GaAs layers grown in high-temperature mode and doped with Si atoms are inserted. The total film thickness was 1 μm.
Using the Hall effect, the type of conductivity for each structure was determined. The results showed that in a film on a (111) A substrate, the doped layers provide hole-type conductivity: a two-dimensional hole concentration of 2.4×109 cm-2, a mobility of 64 cm2/(V×s), and a two-dimensional resistivity of 4.1×107Ω/sq. In the structure grown on a GaAs (100) substrate, electron-type conductivity was observed: a two-dimensional electron concentration of 1.9×107 cm-2, a mobility of 744 cm2/(V×s), and a two-dimensional resistivity of 4.4×108 Ω/sq.
A series of photoconductive antennas (PCA) with plasmonic topology was created on the basis of films (100) and (111) A. The plasmonic lattice period was 500 nm, 250 nm, 100 nm and just a gap[a1] . The clearance of the plasmonic and conventional antenna[a2] was 20 μm.
It has been experimentally shown that the intensity of THz radiation from a GaAs: Si/i-LT-GaAs film on a GaAs (111)A substrate is 5.8 times greater than that of a similar GaAs (100) film. The amplification of THz radiation relative to ZnTe when the bias voltage of up to 60 V is applied reaches values of 14 and 12 for antennas (100) and (111) A, respectively. Due to the screening effect, PCA (100) goes into saturation mode with a lattice period of 100 nm, which does not occur with PCA (111) A. Depending on the lattice period on PCA (111) A, THz radiation exhibits a linear dependence. The sensitivity of PCA on the substrate (111) A is 3.1 times higher than that of a similar PCA (100). The calculated intensity spectra of THz radiation demonstrated a 5-fold and 3-fold output increase in sensitivity with respect to ZnTe in a frequency range of 0.1-3 THz. A at a voltage of 20 volts was observed for created antennas.
The work was supported by the Ministry of Education and Science of the Russian Federation (State task no. 3.7331.2017/9.10 and grant no. 14.Z50.31.0034).
8:00 PM - EM03.18.08
Nano-Architecture Based Plasmonic Field Enhancement in 3D Graphene
Kriti Agarwal 1 , Chunhui Dai 1 , Jeong-Hyun Cho 1 Show Abstract
1 , University of Minnesota, Minneapolis, Minnesota, United States
The self-assembly of patterned 2D graphene nanoribbons can lead to diverse 3D architectures including graphene-based pyramid, tube, and multi-faced cubes. The addition of the extra dimensionality in these 3D structures drastically changes the coupling between the edges and the faces of the graphene leading to distinct plasmon hybridization modes that cannot be realized in 2D graphene ribbons. The number of faces and edges in the 3D structures as well as their inclination angles and distances between them, determines the 3D coupling to a large extent. For the 5-faced graphene pyramids with the inclined faces and edges meeting at the apex, a strong field is scattered in all directions from apex of the pyramid. This strong field in turn creates a very strong volumetric field within the space confined by the faces of the pyramid. A similar volumetric field confinement is obtained for multi-faced cubic structures which is several orders of magnitude higher than the 2D GNR. At the same time, the coupling of adjoining perpendicular faces and edges from all directions also creates large circular hotspots of near-field enhancement that cover the faces of the cube. The tube structure with only 2 edges occurring at the openings of the tube, does not demonstrate similar volumetric confinement at its primary resonance; however, the coupling of the plasmon at the small circular openings of the tube lead to a virtual hotspot area of extremely high near-field enhancement. Furthermore, the versatility of the self-assembly technique allows the realization of the 3D structures from 100s of µm down to below 100 nm. The scaling of the size of the 3D nanostructures, causes a shift in their plasmon wavelength resulting in near-field enhancements that increases by several orders of magnitude. The resulting small scale 3D structures inducing volumetric field enhancement and large area hotspots of electric-field have the potential to be used in diverse plasmonic applications for an increased efficiency of near-field enhancement and high packaging density due to the nanoscale size of 3D structures with highest enhancement.
8:00 PM - EM03.18.09
Probing Optical Environment with Ultra-Thin Films with Eu Ions
Alexis Bullock 1 , Marvin Clemmons 1 , C. Yang 1 , Natalia Noginova 1 Show Abstract
1 Norfolk State University, Center of Materials Research, Virginia Beach, Virginia, United States
New amphiphilic complex Eu(TTA)(L1a), where TTA is thenoyltrifluoroacetonate and L1a is 2-(N, N-diethylanilino-4-yl)-4,6-bis(3,5-dimethylprrazol-1-yl)-1,3,5-triazine, demonstrates highly efficient Eu luminescence with well-resolved predominantly magnetic and electric dipole transitions. This material can be used to probe optical effects, including optical magnetism, in a very close vicinity of nanostructured surfaces as provides an opportunity to fabricate ultra-thin films with controllable thickness by Langmuir-Blodgett technique. The material was synthetized and fully characterized. Modification of spontaneous emission and excitation spectra of Eu has been studied in films deposited on various metal and high-k dielectric surfaces. The branching ratio of the magnetic vs electric transitions showed significant decrease in very close vicinity of metal in the opposite to predictions of the image model for a flat mirror and to what was observed in the films deposited on silicon. The effects depend on the thickness of metal, and related to the near-field excitation of plasmonic modes by both electric and magnetic dipole emitters with different efficiency.
8:00 PM - EM03.18.10
Synthesis of Titanium Nitride Thin Films for Elevated Temperature Plasmonic Application—The Role of Seed Layers for Nucleation
Robert Bowman 1 , William Hendren 1 , Stacey Drakeley 1 , Christopher Lambert 1 , Fumin Huang 1 , Aidan Goggin 2 , Fadi El Hallak 2 , Mark Gubbins 2 Show Abstract
1 , Queen's University Belfast, Belfast United Kingdom, 2 , Seagate Technology, Derry United Kingdom
Noble metals have proven to be the materials of choice for many scientific and laboratory studies of plasmonic phenomena due to their optical performance particularly in the visible and near infra red wavelength range. However, whilst being optically excellent, the noble metals have a metallurgy that makes them less than ideal for the more demanding world of applications and devices. This is especially so with regards plasmonic operation at elevated temperature.
The next paradigm in magnetic data storage technology is heat assisted magnetic recording (HAMR) . Into a conventional magnetic recording read/write head of a hard disk-drive HAMR will see the incorporation of a light source, waveguide and a near field plasmonic antennae. This optical system is used to delivery electromagnetic energy onto the disk surface to heat the local writing area, above the media magnetic coercive field, thereby easing the challenge of writing magnetic data at densities beyond 1Tb/inch^2.
To heat the media above the coercive magnetic field requires an energy density established in the plasmonic near field antennae that indirectly suggests that the plasmonic material is reaching a temperature around 300C. This is a temperature that is proving to be a major technological and materials challenge. In the HAMR system a noble metal based plasmonic antennae undergoes significant recrystalisation. This process alters the behaviour of the material and also its geometry, degrading plasmonic effectiveness, and utlimately leads to a fatigued failure.
There is a ready need to explore alternate materials that may offer suitable plasmonic performance in tandem with a greater resiliance to elevated temperatures. The nitide family of metals have been identified as such a candidate system , .
In this paper we describe a programme of work using ultra high vacumm reactive sputtering at elevated temperatures to make TiN thin films. Importantly, we restrict deposition temperature to around 300C due to thermal budget restrictions required in making a read/write head and through a combination of sputter process conditions (pressure, rates) allied to novel seeding nucleation layers we have created high quality TiN thin films on amporphous substrates. The paper will discuss materials properties and optical response results in context of a figure of merit and contrast with previous published work in TiN for the n & k of the plasmonic material in the HAMR application.
 W. A. Challener et al, Nature Photonics 3, 220 (2009).
 G.V. Naik, V. M. Shalaev & A. Boltasseva, Adv. Mater. 25, 3264 (2013).
 J. Gosciniak et al, Optics Express 25, 5244 (2017)
8:00 PM - EM03.18.11
Magnetic Control of the Chiroptical Plasmonic Surfaces
Irina Zubritskaya 1 , Nicolò Maccaferri 2 , Paolo Vavassori 3 , Alexandre Dmitriev 1 4 Show Abstract
1 Department of Physics, University of Gothenburg, Gothenburg Sweden, 2 , Istituto Italiano di Tecnologia, Genova, Genova, Italy, 3 , CIC nanoGUNE, Donostia–San Sebastian Spain, 4 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States
A major challenge facing plasmon nanophotonics is the poor dynamic tunability. A functional nanophotonic element would feature the real-time sizeable tunability of transmission, reflection of light’s intensity or polarization over a broad range of wavelengths, and would be robust and easy to integrate. Several approaches have been explored so far including mechanical deformation, thermal or refractive index effects, and all-optical switching. However, the remaining issues of the limited extent of the tunability in both amplitude and spectral bandwidth in combination with the required switching timescales, typically down to at least the picosecond range, and the requirement of an easy integration in devices so far prevented the development of a practical adaptive nanoplasmon-based optics.
Chiroptical nanoantennas in 2D and 3D draw the intense research interest due to their ability to introduce the additional spin degrees of freedom of light to various optical components.1 Here we devise an ultra-thin chiroptical surface, built on 2D nanoantennas, where the chiral light transmission is controlled by the externally applied magnetic field. The magnetic field-induced modulation of the far-field chiroptical response with this surface exceeds 100% in the visible and near-infrared spectral ranges, opening the route for nanometer-thin magnetoplasmonic light-modulating surfaces tuned in real time and featuring a broad spectral response.
We propose a plasmonic surface with chiroptical response that is controlled by an external magnetic field over a broad spectral range. For this we design a 2D composite trimer nanoantennas comprising three near-field-coupled nanosized disks of diameters close to 100 nm and identical height of 30 nm, of which one is made of a ferromagnetic material and the other two are made of a noble metal. Individual trimer nanoantennas fill up the macroscale surface, produced with an affordable, highly parallel and cm2-scale bottom-up nanofabrication.2 We consider the simple 2D symmetric geometry and rely on the interplay between the plasmon phases in the trimer 3, making the nanodisks identical in size but of two different materials, namely gold and nickel. The presented compact 2D design promises the easy integration and potentially fast operation in the broad spectral range, enabling this type of functional plasmonic surfaces entering the realm of practical optical devices.
1. Bliokh, K.Y., et al., Spin–orbit interactions of light. Nature Photonics, 2015. 9(12): p. 796-808.
2. Fredriksson, H., et al., Hole–Mask Colloidal Lithography. Advanced Materials, 2007. 19(23): p. 4297-4302.
3. Wang, H., et al., Giant local circular dichroism within an asymmetric plasmonic nanoparticle trimer. Sci Rep, 2015. 5: p. 8207.
8:00 PM - EM03.18.12
Highly-Efficient Magneto-Optic Kerr Effect Microscopy Using Optical Perfect Absorption
Dongha Kim 1 , Jong-Uk Kim 2 , Young-Wan Oh 2 , Byong-Guk Park 2 , Jonghwa Shin 2 , Min-Kyo Seo 1 Show Abstract
1 Department of Physics, Korea Institute of Science and Technology, Daejeon Korea (the Republic of), 2 Department of Materials Science and Engineering, Korea Institute of Science and Technology, Daejeon Korea (the Republic of)
In surface magnetism research, the magneto-optic Kerr effect (MOKE) microscopy has been an indispensable measurement technique due to its extreme instrumental convenience compared to neutron scattering, spin-polarized photoemission, and X-ray magnetic circular dichroism . The MOKE changes the polarization state of the reflected light proportional to the surface magnetization of the magnetic medium . Thus, the spatial distribution and dynamic behavior of the surface magnetization can be mapped by scanning MOKE signals: Kerr rotation or Kerr ellipticity. However, the precise measurements of the MOKE signal and its spatial distribution require to combine highly-efficient detectors and polarizers, since the Kerr coefficient is typically much smaller than the nonmagnetic reflection coefficient so that the Kerr rotation and Kerr ellipticity are only ~0.1 degree or less.
In this research, we employed the perfect absorption based on optical multilayers to reduce the nonmagnetic reflectance and increase the Kerr rotation and Kerr ellipticity. The multilayer structure is consisting of SiO2 (73 nm) / Ni (10 nm) / SiO2 (130 nm) / Al (130 nm) layers on the SiO2 substrate and exhibit near-perfect absorption with a reflectance of ~0.2% at the wavelength of 680 nm. The incident light and the reflected light from the Al mirror layer constructively interfere in the Ni layer. This constructive interference results the perfect absorption and extremely suppresses the nonmagnetic reflection. Transfer matrix calculations estimate that ~97% of the injected light is absorbed by the Ni layer. The Al mirror layer absorbs only ~2.8% of the injected light. In addition, it is also worth noting that the concentration of the electric field in the Ni layer enhances the MOKE itself. We measured the spectra of the Kerr rotation and Kerr ellipticity over the wavelength range from 560 to 840 nm, and observed the resonance of the Kerr effect at the perfect absorption wavelength. The maximum value of the Kerr magnitude, defined as , is ~7.6 degree, which is ~214 times larger than that of the bare single Ni film with the same thickness deposited on the SiO2 substrate. The full-width at half-maximum of the resonant MOKE signal is ~80 nm.
Our technique has more pronounced advantages when applied to an ultra-thin (~1 nm or less) ferromagnetic film supporting hysteresis loops of the vertical magnetization. We examined a Co (1 nm) / Pt (5 nm) bilayer and obtained a highly-enhanced Kerr rotation of ~11.4 degree. Here, the Pt layer acts as not only an underlayer for the magnetic Co film but also an absorbing layer for the perfect absorption. We expect that this highly-efficient MOKE measurement technique will be a useful and universal method for evaluating the properties of magnetic materials and developing magneto-optic devices.
 Stohr, J., Siegmann, H. C. Magnetism : From Fundamentals to Nanoscale Dynamics (Springer, 2006)
 Qiu, Z. Q. et. al. Rev. Sci. Instrum. 71 1243 (2000)
8:00 PM - EM03.18.13
Plasmon Interactions via the Lorentz Force of Larmor Radiation
Haojie Ji 1 , Jacob Trevino 2 , Matthew Moocarme 1 , Luat Vuong 1 2 Show Abstract
1 , Queens College, Flushing, New York, United States, 2 , Advanced Science Research Center of the City University of New York, New York, New York, United States
Over the last several decades, there has been extraordinary interest in a new family of ultrathin optical devices that can shape light propagation at the nanoscale. There are, conventionally, two predominant approaches towards the design of 2D nanophotonic structures. One approach involves the manipulation of the light sub-wavelength diffraction, for example, as in a 2D photonic crystal; this paradigm focuses on the lattice parameters that create the desired band gaps for spectral shaping and light absorption associated with dispersion and interference, through which lossless confinement and guiding of light is achieved. A second approach involves the manipulation of light absorption and scattering interactions, typically in 2D meta-surfaces; The design of novel nano-sized metal unit cells and tailored surface plasmon response can achieve control of the emission, focusing, and phase of light in both near-field and macroscopic interactions. In the latter case, the response of an individual metal nanostructure is often generalized to explain the collective meta-response of a plasmonic photonic crystal in a manner that neglects the interactions between plasmons i.e., the diffractive coupling or dipole interactions between nanostructures.
Here, we experimentally and analytically demonstrate plasmon interactions in free and fixed ensembles of plasmonic nanostructures. By varying the spatial variation, orientation, and alignment of the unit cell, and monitoring the polarization-dependent modes and light-induced mechanical dynamics, we show that there persists significant and widely-overlooked plasmon interactions associated with the coupling between plasmonic structures. The interactions between nanostructures are considered to stem from the Lorentz force arising from the Larmor radiation of adjacent plasmonic resonators because their inclusion in simple models accurately predicts the bonding/anti- bonding modes and electromagnetic forces that are measured experimentally, as well as forces that overcome Brownian forces (pN/mW-cm^2) associated with pattern formation.
We apply both the dipole-dipole interaction model and the surface plasma Larmor radiation models. With numerical simulation, we calculated the field and force profiles induced by the surface plasmons and show that experimental results in impressive agreement with analytical results. We also experimentally observe the emergence of multiple polarization eigenmodes, among other polarization-dependent responses, which cannot be modeled with the conventional formalism of transmission matrices. Our results are vital to the precise characterization and design of plasmonic materials, as well as understanding of plasmonic electrochemistry and plasmon-induced mechanical effects.
8:00 PM - EM03.18.14
In Situ Formation and Assembly of Metallic Nanoparticles in Polymeric Soft Templates towards Fabrication of Metamaterial Structures
Srikanth Nayak 3 2 , Wenjie Wang 2 1 , Tanya Prozorov 2 , Alex Travesset 2 1 , David Vaknin 2 1 , Surya Mallapragada 3 2 Show Abstract
3 Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, United States, 2 Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa, United States, 1 Department of Physics and Astronomy, Iowa State University, Ames, Iowa, United States
A significant challenge in fabricating functional devices based on plasmonic materials and metamaterials is in obtaining uniform nanoparticles with tunable morphology and controlling their spatial organization. Traditional top-down methods are typically limited to the fabrication of meta-surfaces and are expensive. Hence self-assembly processes at the nanoscale are being actively pursued towards the fabrication of bulk metamaterials and plasmonic structures. Self-assembly of polymers into microphase separated domains such as gyroid and lamellar can be utilized for ordering metallic units in such super-lattices. Here, we discuss a novel method for the in situ synthesis of monodisperse metallic nanoparticles in different phases of polymeric gels. We use amphiphilic triblock copolymers belonging to the Pluronic class as reducing and stabilizing agents for the in situ formation of gold and silver nanoparticles. Pluronic polymers contain blocks of poly(ethylene oxide) and poly(propylene oxide) and show temperature driven micellization and gelation due to micellar packing. Co-operative action of multiple poly(ethylene) oxide chains has been shown to reduce metallic precursors to nanoparticles and the adsorption of hydrophobic poly(propylene oxide) passivates the nascent nanoparticle surface against further growth. In this work, the reducing function of the polymer is enhanced by increasing the pH of the gel. Formation of the nanoparticles is tracked by the movement of surface plasmon resonance band corresponding to the gold/silver nanoparticles. A fast nucleation step followed by nanoparticle growth lead to the formation of large number of nanoparticles. Reaction conditions are optimized by tuning the pH, and concentration of polymer and precursor to obtain a high concentration of stable nanoparticles with a narrow size distribution in the polymer gel. The mean size of the formed nanoparticles is controlled within a range of 10 nm to 20 nm by tuning the reaction parameters. Further, with small angle x-ray scattering technique, we observed temperature driven self-assembly of pluronic gels with cubic morphology loaded with metal nanoparticles. Reduction in water content due to drying at ambient conditions leads to the formation of de-mixed lamellae. The lamellar spacing is found to be in the order of formed nanoparticle size and could be tuned by the choice of polymer length. Cryo-TEM of the gels laden with gold nanoparticles indicates a uniform distribution of nanoparticles in the polymer gel. Based on theoretical results pertaining to our system, further exploration of the parameter space to obtain chiral gyroid structures and thereby metallic chiral structures are being pursued.
8:00 PM - EM03.18.15
Self-Assembled Two-Dimensional Photonic Crystals Based on La4Ti9O24
Jiannan Gao 1 , Bo Li 1 , Jianqiang Li 2 Show Abstract
1 , Advanced Materials Institute, Shenzhen Graduate School, Tsinghua University, Shenzhen China, 2 , National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Key Laboratory of Green Process and Engineering, Institute of Processing Engineering, Chinese Academy of Sciences, Beijing China
Self-assembled two-dimensional photonic crystals are demonstrated modeled numerically and experimentally. Amorphous La4Ti9O24 spheres are prepared through containerless solidification, an economical and fancy preparation approach for novel materials. The diameter of the dielectric spheres is 1.02 mm and the permittivity is about 38 in microwave band through the analysis of the simulation and experiments. A series of frame structures manufactured from direct writing, a new method to change the lattices and spacing efficiently, are used to constraint the position of the spheres. The photonic bandgap is about 37.5 GHz in the case of hexagonal structure and 1.2 mm spacing between the center of each sphere. The position of the peak moves as the structure changes. This work demonstrates efficient high frequency photonic crystals and opens up a novel approach that extends to other active optical devices including biosensing, terahertz imaging and energy harvesting by containerless solidification and direct-write technologies.
8:00 PM - EM03.18.16
Self-Assembled, Dichroic, Plasmonic, Nanostructured Titanium Nitride
Sophie Camelio 2 , David Babonneau 2 , Frédéric Pailloux 2 , Gregory Abadias 2 , Nikolaos Pliatsikas 1 , Nikolaos Kalfagiannis 3 , Panos Patsalas 2 1 Show Abstract
2 , University of Poitiers, Chasseneuil-Futuroscope France, 1 , Aristotle University, Thessaloniki Greece, 3 , Nottingham Trent University, Nottingham United Kingdom
Titanium nitride (TiN) has emerged as a promising alternative plasmonic material, which combines a variety of assets such as optical response similar to gold, refractory character, low work function and its growth being CMOS compatible. While its refractory character is an asset in terms of performance, it is also a liability regarding its growth. In particular, its high melting point results in reduced diffusivity of deposited species rendering fine grains during growth and reducing the potential of self-assembly of TiN nanostructures by thermal or laser processing. Consequently, TiN nanostructures were formed by top-down processes based on lithography methods, so far. In this work we present a two-step process for the formation of self-assembled, dichroic, nanostructured TiN with substantial plasmonic response. It is based on exploiting the shadowing effects during the glancing angle deposition (GLAD) of TiN on pre-patterned rippled substrates. The first step of the process is the patterning of an alumina thin film by glancing angle Xe+ irradiation to form periodic ripples [Babonneau et al, Phys. Rev. B 95,085412 (2017)]. The second step is the GLAD of TiN on the rippled alumina surface that enables the growth of self-assembled and well-aligned nanostructures along the ripples, which exhibit strong dichroism and plasmonic activity. For the GLAD two versions of sputter-deposition were used (dual ion beam sputtering and magnetron sputtering), which were reported to result in different microstructures of continuous TiN films [Koutsokeras et al, J. Appl. Phys. 110, 043535 (2011)]; indeed, it is confirmed that the two methods of deposition resulted in different morphology and plasmonic response of the TiN nanostructures. The plasmonic response and dichroism of the TiN nanostructures were evaluated by polarized optical transmittance measurements, the morphology by transmission electron microscopy and atomic force microscopy, and the surface chemistry by x-ray photoelectron spectroscopy. The optical response of the nanostructures was evaluated by finite-difference time domain calculations, which revealed the excellent consistency of the optical response with the microstructure and chemistry of the nanostructures.
8:00 PM - EM03.18.17
Silver Nanoparticle/Semiconducting Polymer Hybrid Spasers
Jill Tracey 1 , Deirdre O'Carroll 1 2 Show Abstract
1 Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States, 2 Materials Science and Engineering, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
Spasers (Surface Plasmon Amplification by Stimulated Emission of Radiation) are the nanoscale counterpart to a laser. They are a coherent light source which beats the diffraction limit of light by utilizing nanoparticles which support localized surface plasmon resonances to confine light into nanoscale volumes. However, only a few demonstrations of spasers have been shown to date, each of which have used gold for the nanoparticle cavity and laser dyes as the active gain medium, resulting in emission wavelengths in the region of 525 - 627 nm. To improve the efficiencies and emission range of spasers other materials combinations must be implemented. In addition, using different constituents would allow a wider range of wavelengths to be accessed which could lead to more applications of spasers. For example, unlike gold, silver has a low loss surface plasmon resonance which is tunable across the entire visible spectrum. Blue wavelengths are inaccessible using gold due to gold’s interband electronic absorptions at wavelengths below about 550 nm. Silver’s surface plasmon resonance tunability across the entire visible spectrum also allows for the implementation of different gain media such as organic semiconducting conjugated polymers which have higher chromophore densities, superior synthetic tunability, strong room-temperature excitonic emission, biocompatibility, and more facile processing compared to inorganic semiconductors and laser dyes. By utilizing silver and semiconducting polymers for spasers the operation range of these plasmonic devices is expanded to shorter wavelengths than what has currently been demonstrated.
The goal of this research project is to fabricate thin film nanoparticle/polymer hybrid films which can be utilized to demonstrate low threshold, functioning spasers at blue wavelengths. To verify spasing is occurring two tests are performed, first, photoluminescence spectroscopy is utilized to observe spectral narrowing, and, second, pump power-dependent spectroscopyis employed, to observe nonlinear (specifically, linear to superlinear) output intensity behavior. Both of these test are used to observe stimulated emission which is characteristic of spasing. This presentation will focus on the fabrication and characterization of planar thin film array configurations of spasers. Many variables have been investigated to achieve functioning spasers, including silver nanoparticle size, silver nanoparticle density, and semiconducting polymer layer thickness. Our results indicate that spasing is achievable utilizing 60 nm diameter silver nanoparticles as the plasmonic resonator and poly(9,9-di-n-octylfluorenyl-2,7-diyl) as the gain medium. However all three of these variables (nanoparticle size, nanoparticle density, polymer film thickness) play a key role in the functionality of the spasers, and will be discussed in this presentation.
8:00 PM - EM03.18.18
Nanowire Antenna Systems with Substrate-Mediated Tunability and High Directionality
Mohammad Mahdi Salary 1 , Hossein Mosallaei 1 Show Abstract
1 Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts, United States
In recent years, there has been a growing demand for highly directional antennas operating in visible and near-infrared frequencies which enable miniaturization of wireless devices. For this purpose, arrays of plasmonic and dielectric antennas have been used based on phased array, Yagi-Uda and holographic design approaches. However, in these approaches the overall size of the radiating system turns out to be greater than the radiation wavelength.
In order to downscale directive antenna platforms into subwavelength footprints, individual dielectric and plasmonic elements coupled to dipolar emitters have been investigated. These configurations have been shown to enhance the directivity without a significant increase in the size of antenna system.
As a next frontier, realization of tunable antenna platforms whose beaming angle can be controlled on-demand is a highly desirable for a variety of applications. In this work, we demonstrate substrate-supported nanoantennas incorporating electromechanical and electro-optical effects can be used for this purpose. To this end, we consider a silicon nanowire antenna on a layered substrate; excited by a near-by point source. A robust and efficient semi-analytical framework is developed for characterization of far-field emission properties of such antenna system which facilitate quantification and optimization of performance characteristics. The method is subsequently used to design tunable directional antenna systems in different frequency regimes of visible, near-infrared, and far-infrared through integration of nanoactuators and electro-optical materials, such as transparent conductive oxides and graphene into the substrate. Each configuration is optimized to achieve maximal steering range while attaining a proper gain. The design approach devised here exploits the interference effects from the substrate and the symmetry breaking effects introduced by the nanowire antenna at the same time to achieve directionality and tunability. The presented antenna systems are ideal candidates for subwavelength antenna synthesis in the account of enhanced directionality and real-time tunability.
8:00 PM - EM03.18.19
Fabrication of Optically Transparent Laser Filter by Nanoparticles Composite
Debajyoti Mondal 1 , Themos Kallos 2 , George Palikaras 2 , Felipe Chibante 1 Show Abstract
1 Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada, 2 , Metamaterial Technologies Inc., Dartmouth, Nova Scotia, Canada
Powerful and cheap hand-held lasers are increasingly available on the internet and in stores. Despite the fact that lasers when aimed at people or treated as toys are illegal and potentially dangerous, such misuses are on the rise. Based on surface plasmon resonance of gold nanoparticles (AuNPs), flexible laser filters were fabricated by incorporating AuNPs of specific sizes and shape in organic polymers by involving the integration of a number of different technologies (dip coating, thermal annealing, spin coating, etc.). Initially, spherical AuNPs of 25-40nm sizes were synthesized in laboratory scale followed by the scaling up of the same product keeping the optical absorption maximum at 532 nm by maintaining precise control over the size distribution of the AuNPs. In the next stage AuNPs were integrated into a transparent host polymer to produce a polymer nanocomposite. Such manufacturing processes of transparent polymer nanocomposite is energetically viable to make and thermally stable from -50oC to 400oC .Thin transparent films made from this nanocomposite has shown promising results as flexible filters for green lasers (532 nm).
8:00 PM - EM03.18.20
A Tunable Plasmonic Biosensing Platform Based on Two-Dimensional Hydrogenated Molybdenum Oxides
Baoyue Zhang 1 , Jian Zhen Ou 1 Show Abstract
1 , RMIT University, Melbourne, Victoria, Australia
Plasmon resonances are commonly seen in noble metal systems, showing enhanced absorption and scattering resonances in certain wavelengths that can be utilized in many fields, including photovoltaics, surface enhanced spectroscopies, sensors and possibly optical communications. However, the plasmonic responses of such systems are permanently locked in and cannot be actively controlled once they have been engineered through their intrinsic parameters and specific morphologies. The recent demonstration of plasmon resonances in sub-stoichiometric and doped transition metal oxides have presented several advantages over the conventional noble metal plasmonic systems, particularly in the tunability of plasmonic resonance peaks, which provide opportunities to create sensitive measurement tools and new technologies in optics and biological application. In particular, the free charge carrier concentration in transition metal oxides can be manipulated upon the change of dopant concentration, which can result in the plasmon resonances in the visible and NIR regions if a significant number of dopants presented in the host material. This is an important criterion for practical biological application. In addition, the doped transition metal oxides show high sensitivity to oxidants and reductants that result in the change of their plasmonic properties.
In this work, we demonstrate a hydrothermal method to manipulate the H+ dopant concentration into the two-dimensional (2D) MoO3 based on ammonia molybdite salt and organic acid. The H+ concentration is varied between 0.3 and 1.55 for H+/MoO3.and hence the plasmon resonance peaks of the doped compounds can be tuned throughout the whole visible light range. We then utilize a facile LED-photodetector platform to incorporate the 2D hydrogenated MoO3 for sensing glucose. At the LED wavelength of 410 nm, a limit of detection of ~100 nM L-1 is achieved for the doped compound with the H+/MoO3 ratio of 1.55. The response time is also impressive as averagely 4 to 10 s is observed for glucose with concentration between 500 nM L-1 and 50mM L-1. This performance is much better than those based on conventional noble metal based plasmonic system, making the 2D hydrogenated MoO3 a promising candidate for the emerging tunable plasmonic biosensing platform.
Stephanie Law, University of Delaware
Viktoriia Babicheva, ITMO University
Svetlana Boriskina, Massachusetts Institute of Technology
Frank Neubrech, University of Heidelberg
EM03.19: Plasmonic Sensing
Friday AM, December 01, 2017
Hynes, Level 1, Room 104
8:15 AM - *EM03.19.01
Nanoscale Hydrogenography of Individual Magnesium Nanoparticles
Florian Sterl 1 , Heiko Linnenbank 1 , Tobias Steinle 1 , Florian Mörz 1 , Nikolai Strohfeldt 1 , Harald Giessen 1 Show Abstract
1 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Stuttgart Germany
Magnesium has been widely investigated as a promising candidate for solid-state hydrogen storage, due to its ability to absorb up to 7.6 wt% of hydrogen gas. This high capacity of magnesium hydride (MgH2), alongside a large range of other metal hydrides, makes it possible to compress hydrogen fuel to much smaller volumes than pressurized or even liquefied H2. This is an important factor for the development of H2 as an energy carrier, for example in mobility applications, since fossil fuels such as gasoline possess a significantly higher volumetric energy density.
The formation MgH2 is accompanied by a metal-to-insulator transition. This allows for monitoring the kinetics of the hydrogenation process by optical measurements, thus probing the electronic properties. This technique, termed hydrogenography, has been used to observe the nucleation and growth of MgH2 domains in Mg films . The strong contrast between metallic Mg and dielectric MgH2 has also been employed in active plasmonic nanostructures, which can be switched off by exposure to H2 and on by either heating or exposure to oxygen . Like all far-field optical methods, however, these investigations suffer from the diffraction limit and thus possess only limited spatial resolution, therefore preventing the direct observation of the hydrogenation process on the nanoscale.
We overcome this limitation by employing scattering-type scanning near-field optical microscopy and atomic force microscopy. This technique enables us to map the local dielectric properties on the particle surface at different stages of hydrogenation and dehydrogenation, probing thus the electronic properties and hence the local material composition with a spatial resolution on the order of 10 nm. The validity of this novel approach is confirmed by monitoring the far-field scattering spectra of the particles, which exhibit plasmonic resonances in the visible wavelength range, using single-particle dark-field spectroscopy.
Upon monitoring the kinetics of hydrogen absorption and desorption in such polycrystalline nanoparticles we show that the nucleation of this process progresses within individual crystallites. Our combined measurement techniques additionally corroborate a correlation between structural and electronic properties during this dynamic process.
 L. Bannenberg, H. Schreuders, L. van Eijck, J. Heringa, N. Steinke, R. Dalgliesh, B. Dam, F. Mulder,and A. van Well, “Impact of Nanostructuring on the Phase Behavior of Insertion Materials: The Hydrogenation Kinetics of a Magnesium Thin Film”, J. Phys. Chem. C, 120, 10185-10191 (2016).
 F. Sterl, N. Strohfeldt, R. Walter, R. Griessen, A. Tittl, and H. Giessen, “Magnesium as Novel Material for Active Plasmonics in the Visible Wavelength Range,” Nano Lett., 15, 7949-7955 (2015).
8:45 AM - EM03.19.02
In Situ Visualization of Plasmon-Induced Hydrogenation Reactions in Individual Palladium Nanocubes
Michal Vadai 1 , Daniel Angell 1 , Fariah Hayee 1 , Katherine Sytwu 1 , Jennifer Dionne 1 Show Abstract
1 , Stanford University, Stanford, California, United States
Metallic nanoparticles (NPs) are emerging as a new class of heterogeneous photocatalysts due to their ability to efficiently absorb light and convert it into chemical energy. Compared to traditional photocatalysts, plasmonic NPs offer electromagnetic field enhancement, localized heating and efficient hot carrier excitation. Many plasmon photocatalyst studies are based on ensemble measurements, in which nanoparticle heterogeneity conceals many important and interesting structure-dependent catalytic properties. Further, many studies lack the nanometer-scale spatial resolution to help elucidate the role of plasmons in photocatalytic reactions.
Here, we provide the first experimental visualization of a plasmon-induced reaction at the single nanoparticle level. We study the photo-catalytic dehydrogenation of individual palladium nanocubes using an environmental transmission electron microscope (ETEM) combined with light excitation. Pd nanocubes with edge lengths of approximately 50 nm are colloidally synthesized and positioned next to lithographically patterned Au nanodiscs with size ranging between 50 nm and 100 nm. The Pd nanocubes and Au nanodiscs form antenna (Au) – reactor (Pd) systems of varying interparticle separation, from touching to 20nm. Under controlled hydrogen pressure conditions (10 Pa – 60 Pa), we study the kinetics of the desorption reaction, triggered by the optical excitation of plasmons in the adjacent Au nano-antennas. Under illumination, the desorption rate of hydrogen from the Pd nanocubes is significantly enhanced, pushing the system out of equilibrium and thus resulting in a phase change from the hydrogen-rich β phase to the hydrogen-dilute α phase. These changes are monitored in real time using a combination of single particle electron diffraction and direct imaging. This photocatalytic process is wavelength dependent, with a maximum rate at the plasmon resonance of the Au particles. Further, distance-dependent measurements show that the rate enhancement is less pronounced in the Au-Pd dimers with larger separations, with a response time ranging from 2 to 60 sec. The unique capabilities of combined environmental electron microscopy and optical illumination allow us to study photo-induced reactions with unprecedented resolution, unravelling the role of hot carriers, local heating, and light-mediated ion and electron transfer in nanomaterials.
9:00 AM - EM03.19.03
Synthesis and Phase Transfer of Gold-Containing Bimetallic Nanoparticles for Application in Biosensors
Jing Li 1 , Jessica Luo 1 , Michael Kozma 1 , Shiyao Shan 1 , Ning Kang 1 , Shan Yan 1 , Zakiya Skeete 1 , David Truong 1 , Jin Luo 1 , Chuan-Jian Zhong 1 Show Abstract
1 , State University of New York at Binghamton, Binghamton, New York, United States
The gold-based nanoparticles have been widely used in biosensing and biodetection because of their strong plasmonic properties and highly biocompatible characteristics. However, the high cost and limited synthesis scalability of gold itself constitute an important factor in limiting its widespread applications in many areas. This presentation reports new findings of an investigation of the synthesis of composition-tunable gold-containing bimetallic nanoparticles, e.g., bimetallic AuCu nanoparticles, via a highly-scalable route under room temperature reaction in aqueous solution. The sizes and compositions are shown to be highly controllable. The nanoparticles can be easily functionalized with hydrophobic and hydrophilic surface properties, exhibiting excellent optical properties for exploitation as Surface Enhancement Raman Scattering (SERS) nanoprobes and thin film assemblies. This finding is of great significance for the development of scalable and low-cost nanoparticles for applications in biosensors.
9:15 AM - EM03.19.04
Hybridized Plasmonic Nanostructures for Enhanced Sensing
Ashok Kodigala 1 , Thomas Lepetit 1 , Boubacar Kante 1 , Jun-Hee Park 1 Show Abstract
1 , University of California, San Diego, La Jolla, California, United States
Plasmonics and its applications have garnered ample attention over the years. These applications range from chemical and biological sensors to enhanced photovoltaics. We design 3D plasmonic structures with exceptional point (EP) singularities. Exceptional Points (EPs) are singularities of open systems where at least two complex eigenmodes coalesce [1-2]. They manifest themselves by the simultaneous degeneracy of both resonant frequencies and linewidths. These points are highly sensitive to external perturbations as even a tiny variation will lift the degeneracy and cause splitting of both resonant frequencies and linewidths. These results make it possible to envision a highly sensitive molecular sensor.
9:30 AM - EM03.19.05
Degenerately Doped Metal Oxide Nanocrystals as Plasmonic and Gas Sensors
Marco Sturaro 1 , Enrico Della Gaspera 2 , Massimo Guglielmi 1 , Alessandro Martucci 1 Show Abstract
1 , Universita di Padova, Padova Italy, 2 , RMIT University, Melbourne, Victoria, Australia
Highly doped wide band gap metal oxides nanocrystals have recently been proposed as building blocks for applications as transparent electrodes, electrochromics, plasmonics and optoelectronics in general. Here we demonstrate the application of ZnO doped with gallium (GZO), aluminum (AZO), silicon (SZO) and germanium (GeZO) nanocrystals as novel plasmonic sensors for the detection of hazardous gases including hydrogen (H2) and nitrogen dioxide (NO2).
GZO, AZO, SZO and GeZO nanocrystals are obtained by non-aqueous colloidal heat-up synthesis with high trasprency in the visible range and strong localized surface plasmon resonance (LSPR) in the near IR range, tunable with dopant concentration (up to 20% mol nominal). Thanks to the strong sensitivity of the plasmon resonances to chemical and electrical changes occurring at the surface of the nanocrystals, such optical features can be used to detect the presence of toxic gases. By monitoring the changes in the dopant-induced plasmon resonance in the near infrared, we demonstrate that GZO, AZO, SZO and GeZO thin films prepared depositing an assembly of highly doped ZnO colloids are able to optically detect both oxidizing and reducing gases at mild (< 100 °C) operating temperatures. Combined optical and electrical measurements show that trivalent dopants within ZnO nanocrystals enhance the gas sensing response compared to undoped ZnO. Moreover, improved sub-ppm NO2 gas sensitivity is achieved by activating the sensors response through combined purple-blue (λ=430nm) light irradiation and mild heating at 75 °C. In addition, these thin films based on degenerately doped semiconductors are highly transparent in the visible range, enabling the fabrication of “invisible” gas sensors. The use of highly doped semiconductive nanocrystals for both IR plasmonic and chemiresistive sensors represent a marked advancement towards the development of highly sensitive and selective devices.
9:45 AM - EM03.19.06
Targeted Protein Detection Using Gold Nanosphere-Based Functionalized Plasmonic Toroidal Terahertz Metamaterials
Arash Ahmadivand 1 , Burak Gerislioglu 1 , Nezih Pala 1 Show Abstract
1 , Florida International University, Miami, Florida, United States
Terahertz (THz) plasmonic systems have received growing attention recently due to providing reliable features for various applications from biological sensing to imaging. In this study, using planar plasmonic metasurfaces consisting of well-engineered microblocks, we successfully excited toroidal dipoles with high-quality (high-Q) factor in THz spectra. To confirm the formation of a closed-loop magnetic current, we employed both numerical analysis (Finite-Difference Time-Domain (FDTD)) and experimental results. Taking the advantage of high-Q toroidal dipole moment in the THz domain, we developed a promising platform for biosensing applications. To this end, we introduced bioready gold nanospheres with the diameter of 40 nm into THz metasurface to improve the sensitivity of the metasurface. By analyzing the effect of plasmonic nanospheres on the quality and position of toroidal dipole, we utilized the prepared THz plasmonic metasurface to detect Zika-virus (ZIKV) envelope protein using a specific ZIKV antibody. The sharp toroidal resonant moment supported by the surface functionalized structures shifts as a function of the ZIKV protein for ultralow concentrations in the range of picomolar (pM). The results of sensing experiments reveal rapid, accurate and quantitative detection of proteins. We believe that the proposed toroidal metasurface paves new methods for developing cost-effective, and efficient THz plasmonic sensors for infection and targeted bio-agent detection.
EM03.20: Infrared Plasmonic Structures
Friday PM, December 01, 2017
Hynes, Level 1, Room 104
10:30 AM - *EM03.20.01
Fundamental limits to light-matter interactions
Owen Miller 1 Show Abstract
1 , Yale University, New Haven, Connecticut, United States
Nanophotonics is developing at a rapid pace, with ever more materials, form factors, and structural degrees of freedom now available. To confront these large design spaces, and leverage them for transformative technologies, new theoretical tools are needed. In tandem with large-scale computational design, there is significant opportunity to identity fundamental limits to what is possible in light--matter interactions. I show that passivity considerations constrain maximum optical response, answering foundational questions such as: (1) how can we achieve low-loss plasmonics?, (2) what is the analog of a “blackbody” in the near field?, and (3) what is the maximum spontaneous-emission rate of a free electron?
11:00 AM - EM03.20.02
Design of Plasmonic-Enhanced Platinum Substrates for Infrared Catalysis
Hossein Alizadeh 2 1 , Luca Dal Negro 2 1 3 Show Abstract
2 Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States, 1 Photonics Center, Boston University, Boston, Massachusetts, United States, 3 Physics, Boston University, Boston, Massachusetts, United States
Platinum is an important technological material due to its low reactivity, large corrosion resistance and ideal catalytic properties The most common application of platinum is as a catalyst in chemical reactions, often as platinum black. Platinum was first used to catalyze the ignition of hydrogen. It also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen and it is used in fuel cells as a catalyst for the reduction of oxygen, in ethanol production and for C-C bond breaking. The wide range of catalytic applications of platinum would highly benefit from more efficient reactions with chemical agents in controllable nanoscale environments, particularly for infrared catalysis. Due to a large extinction coefficient, platinum has been traditionally considered a poor optical material.
In this work we show for the first time that platinum nanostructures can be designed to achieve active plasmonic field enhancement and resonant energy concentration in the infrared spectral range. The structures that we present here are ideally suited for infrared photo-catalysis in the 5-10µm range. More specifically, we propose a platinum grating structure on silicon that can be utilized to generate hybrid photonic-plasmonic modes with enhanced and localized fields on the surface of platinum thin films. By considering realistic materials dispersion properties within a full-vector three-dimensional Finite Difference Time Domain (FDTD) approach, we demonstrate that our proposed design can greatly improve the spatial overlap between enhanced electric fields and platinum nanostructures in the presence of catalytic fuel. Infrared plasmonic field concentration and enhancement can lead to the development of novel Pt nanoscale catalytic converters with significantly increased efficiency, reduced cost and footprint for energy harvesting and conversion applications.
11:15 AM - EM03.20.03
Metal-Insulator-Metal Plasmonic Infrared Resonant Absorbers with Dispersive Dielectrics
Seth Calhoun 1 , Vanessa Lowry 1 , Reid Stack 1 , Rachel Evans 1 , Chris Fredricksen 1 , Janardan Nath 1 , Robert Peale 1 , Evan Smith 2 3 , Justin Cleary 2 Show Abstract
1 , University of Central Florida, Orlando, Florida, United States, 2 Sensors Directorate, Air Force Research Laboratory (AFRL), Dayton, Ohio, United States, 3 , Wyle KBR, Dayton, Ohio, United States
Metal-insulator-metal (MIM) plasmonic resonant absorbers comprise an optically opaque conducting ground plane, a dielectric of subwavelength thickness, and thin separated metal structures (typically squares) on the top surface. The commonly-used dielectric SiO2 has a strong absorption feature near 9 micron wavelength and correspondingly strong dispersion for the refractive index in the technologically important 8-12 micron long-wave infrared (LWIR) region. This dispersion results in a multitude of plasmonic absorption resonances that span the LWIR, which provides an opportunity for enhancing sensitivity of LWIR bolometric and pyroelectric detectors. In contrast, dielectrics with comparatively low LWIR dispersion, such as TiO2, AlN, and Al2O3, give isolated LWIR resonances that are more suitable for spectral sensing applications. These dispersion-dependent features for infrared MIM devices are demonstrated by experiment, electrodynamic simulation, and an analytic model based on standing waves under the surface structures. Geometrical parameters are optimized via simulation to give strongest absorption, and predictions are confirmed by experiment.
11:30 AM - EM03.20.04
Fano Resonances in the Near Field Radiative Heat Transfer
Raul Esquivel-Sirvent 1 , Giuseppe Pirruccio 1 , Jaime Perez-Rodriguez 1 Show Abstract
1 , Universidad Nacional Autonoma de Mexico, Mexico, FDM, Mexico
In this work, we show the existence of Fano-like resonances in the spectral radiative heat transfer between two bodies at a different temperatures. With the Fano resonances, suppression and enhancement of the spectral heat flux at specific wavelengths is possible .
To produce the Fano resonances, we make use of the plasmon-phonon coupling in a symmetric nano-cavity composed of a polaritonic material (NaBr) coated with a metallic layer (Bi). The plasma frequency of the metallic layer is changed by varying its porosity. The effective dielectric function and effective plasma frequency are calculated using an effective medium approximation [2,3].
By matching the plasma frequency of the metallic layer with the phonon modes of the polaritonic material, strong hybridization of the plasmonic and phononic modes sustained by the multilayer is possible. This leads to the opening of a thermal band gap, where heat transfer in the coupled system is inhibited for all wave vectors and for wavelengths at which the individual constituents are thermally transmissive.
Furthermore, we show that the width of the thermal bandgap is controlled changing the geometrical parameters of the nanocavity.
 J. E. Perez-Rodriguez, G. Pirruccio, R. Esquivel-Sirvent, "Fano Interference for tailoring near-field radiative heat transfer", ArXiv 1706.01550 Cond. Matt. (2017).
 R. Esquivel-Sirvent, “Ultra thin metallic coatings to con- trol near field radiative heat transfer,” AIP Advances 6, 095214 (2016).
 E. Y. Santiago, J. E. Perez-Rodriguez, and Raul Esquivel-Sirvent, “Dispersive properties of mesoporous gold: van der waals and near-field radiative heat interac- tions,” J. Phys. Chem. C. 121, 12392 (2017).
11:45 AM - EM03.20.05
Investigation of Unpatterned Etching of Nanostructures in Immobilized Cubic-Boron Nitride for Infrared Nanophotonic Elements
Ioannis Chatzakis 1 , Athith Krishna 2 , Alexander Giles 1 , Nicholas Sharac 1 , Michael Spencer 2 , Joshua Caldwell 1 3 Show Abstract
1 , U.S. Naval Research Laboratory, Washington, District of Columbia, United States, 2 , Cornell University, Ithaca, New York, United States, 3 Electrical and Mechanical Engineering, Vanderbilt University, Nashville, Tennessee, United States
Phonon polaritons (PhPs) are long-lived electromagnetic modes that originate from the coupling of infrared photons with the bound ionic lattice of a polar crystal. These PhPs can be supported and stimulated within the Restrahlen band, which is the spectral region between the longitudinal and transverse optical phonons of the polar material. Such PhPs, like their surface plasmon polariton counterparts, offer the ability to confine the incident light beyond the diffraction limit. Cubic-Boron nitride (c-BN) is such a polar, semiconductor material, which due to the light atomic masses can support high frequency optical phonons, resulting in a Restrahlen band between 1070 cm-1 and 1300 cm-1 (~9.35-7.69 m). This range overlaps with a broad number of molecular vibrational modes and therefore makes this material well-suited for realizing enhanced spectroscopy through the surface enhanced infrared absorption (SEIRA) process. Here, we report on random arrays of c-BN nanostructures fabricated via an unpatterned reactive ion etching process. The etching results in elliptical-cylinder-shaped c-BN structures on the order of a micrometer in size depending on the etching conditions. FTIR reflection spectra suggest the presence of localized surface PhPs within the Restrahlen band, with quality factors in excess of 40 observed, despite linewidth broadening due to the inhomogeneous distribution of nanostructure sizes and shapes. Through further investigations of the etching process and therefore developing a controlled approach to c-BN nanostructure fabrication, we believe these can provide the basis of next generation infrared optical components like antennas for communication, improved chemical spectroscopies, and enhanced emitters, sources and detectors.