Symposium Organizers
Viktoriia Babicheva, Georgia State University
Alexandra Boltasseva, Purdue University
Harald Giessen, University of Stuttgart
Pavel Ginzburg, Tel Aviv University
Symposium Support
Neaspec GmbH
NKT Photonics Inc.
ED10.1: Active and Tunable Materials
Session Chairs
Viktoriia Babicheva
Matthew Sheldon
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 131 B
11:30 AM - ED10.1.01
Continuous Beam Steering at 1500 nm with Gate-Tunable Conducting Oxide Reconfigurable Metasurfaces
Ghazaleh Kafaie Shirmanesh 1 , Ragip Pala 1 , Ruzan Sokhoyan 1 , Muhammad Alam 1 , Harry Atwater 1
1 , California Institute of Technology, Pasadena, California, United States
Show AbstractWe report design principles for and experimental realization of gate-tunable metasurfaces that enable electrical phase control of plane wave reflection from the metasurface. The presented design utilizes field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna elements which are configured in reflectarray geometry1. Here, we demonstrate continuous beam steering by applying independent biases to individual antenna elements of the reflectarray metasurface.
The metasurface we study consists of an aluminum back plane, an ITO layer followed by 5 nm thick HfO2 gate dielectric layer and a periodic array of 70nm thick aluminum fishbone antenna reflectarray on top. By applying an electrical bias between the antenna and ITO layers, a charge accumulation or depletion layer is formed in ITO at the interface of ITO and HfO2 layers. This results in modulation of the complex permittivity of ITO, which alters the interaction of the incident light with the metasurface and modulates the reflection.
We measured a phase shift of 270o by analyzing the reflection phase from the metasurface elements using a Michelson interferometer. Next, we applied independent bias to each antenna element to demonstrate continuous beam steering with steering angles up to 40o. Electrically gated phase control for individual metasurface elements opens the path to many applications in ultrathin optical components for imaging and sensing technologies, such as reconfigurable beam steering devices, dynamic holograms, tunable ultrathin lenses, nanoprojectors, and nanoscale spatial light modulators.
1. Huang, Y.-W. et al. Gate-Tunable Conducting Oxide Metasurfaces. Nano Letters 16, 5319-5325 (2016).
11:45 AM - *ED10.1.02
Ultrafast and Nonlinear Plasmonics with Alternative Material Platforms
Vladimir Shalaev 1 , C. DeVault 1
1 , Purdue University, West Lafayette, Indiana, United States
Show AbstractSurface plasmon polaritons are the collective and coherent coupling of electromagnetic fields with a material’s underlying elementary charges. For noble metals, the linear optical properties mediated by plasmons polaritons are generally well understood; however, the study of ultrafast and nonlinear plasmon interactions in metals is attracting wide attention due to the potential for enhancing functionality in nano-scale photonic devices and applications. Although noble metals are ideally suited for supporting plasmon excitations, their fundamental drawbacks are significant and include low melting points, chemical instabilities, and an incompatibility with standard CMOS processing techniques. Here we investigate the ultrafast and nonlinear properties of two alternative plasmonic materials, namely the transition metal nitride, titanium nitride (TiN), and the transparent conducting oxide, aluminum-doped zinc oxide (AZO). We observe a large third-order nonlinearity in titanium nitride thin films—comparable to nonlinearities in gold—which is strongly tunable via the dependence on stoichiometry, growth conditions, and crystallinity. In addition, we performed time-resolved spectroscopy of TiN films in order to elucidate the ultrafast electron dynamics and to demarcate which transitions contribute to the third-order nonlinearities. We also perform time-resolved spectroscopy on aluminum-doped zinc oxide films. These films exhibit an unprecedentedly large and ultrafast (sub-picosecond) response. Furthermore, we find that this response is significantly enhanced near the epsilon-near-zero point of our film and the corresponding extracted modulation of refractive index is on the order of unity. Together, both TiN and AZO constitute two alternative plasmonic materials with exceptional ultrafast and nonlinear properties that might engender the next class of material platforms for the development and realization of practical plasmonic technologies.
12:15 PM - *ED10.1.03
Electrically Tunable Antennas
Mark Brongersma 1
1 , Stanford University, Stanford, California, United States
Show Abstract
The scaling of active photonic devices to deep-submicron length-scales has been hampered by the fundamental law of diffraction and the absence of materials with sufficiently strong electrooptic effects. Here, we demonstrate a solid state electro-optical switching mechanism that can operate in the visible spectral range with an active volume of ~ 10-6 mm-3 or about 10-5 l3, i.e. comparable to the size of the smallest active electronic components. The switching mechanism relies on electrochemically displacing atoms inside the nanometer-scale gap between two crossed metallic wires forming a crosspoint junction. Such junctions afford extreme light concentration and display singular optical behavior upon formation of a conductive channel. We illustrate how this effect can be used to actively tune the resonances of a plasmonic antenna. The tuning mechanism is analyzed using a combination of electrical and optical measurements as well as electron energy loss (EELS) in a scanning transmission electron microscope (STEM).
12:45 PM - ED10.1.04
Spatiotemporal Light Control in Dielectric Metasurfaces for Ultrafast Laser Beam Steering
Amr Shaltout 1 , Konstantinos Lagoudakis 1 , Jelena Vuckovic 1 , Vladimir Shalaev 2 , Mark Brongersma 1
1 , Stanford University, Stanford, California, United States, 2 , Purdue University, West Lafayette, Indiana, United States
Show AbstractLaser beam steering is a pivotal component in numerous current and developing applications including LIDAR, laser scanners, autonomous vehicles, geographical mapping and imaging applications. Faster laser scanning is directly related to higher frame rates as well as improved imaging resolution. Rapid beam rotation is typically achieved using optical phased-arrays implemented with liquid crystals 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. To further enhance the scanning time, we present a novel methodology of laser beam steering based on light-matter interaction between a silicon-based metasurface and a mode-locked laser with a frequency-comb spectrum (i.e., an equally spaced phased-locked frequency lines).
Over the past few years, metasurfaces have been used with CW lasers to engineer the spatial distribution of light in the far-field leading to successful implementations of light bending, meta-lenses, meta-holograms and other applications. This is achieved through coherent interference of scattered waves from an array of nano-structured elements that are locally controlling the optical phase-front. These applications require spatial coherence which imposes employment of a monochromatic laser, but this leads only to generation of static optical patterns. Instead, we demonstrate that it is possible to generate dynamic patterns through coherent interference of waves in 4D space-time if the CW laser is replaced with a frequency-comb source. In our work, the metasurface is judiciously designed such that the spatial distribution of light generated in the far-field is different for each of the frequency-comb spectral lines. Because the spectral lines are phase-locked, their different optical patterns are constructively interfered at a narrow angle in the far-field leading to directivity of the laser beam. The temporal coherence of the phase-locked spectral components causes the direction of the constructed laser beam to be at a time-dependent rotating angle; and henceforth, beam steering is realized. The generated laser scans an angle of view in the order of ±450, over a time interval about 100 ps.
This new methodology produces beam steering with a wide angle of view and 4-5 orders of magnitude enhancement in scanning time. In addition to the laser steering application, the integration of metasurfaces and frequency-comb sources broadens the scope of flat photonics towards engineering spatiotemporal optical patterns.
ED10.2: Optoelectronics and Hybrid Nanostructures
Session Chairs
Koray Aydin
Viktoriia Babicheva
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 131 B
2:30 PM - *ED10.2.01
Nonlinear Optics with Metasurfaces—Integration with Semiconductor Heterostructures
Igal Brener 1 2
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 , Center for Integrated Nanotechnologies, Albuquerque, New Mexico, United States
Show AbstractTremendous progress has been made over the last few years in the area of passive metasurfaces. Several groups have shown exciting results in fundamental science such as modified Snell’s laws, control of emission, etc. and also in applications such as flat optics and holographic elements. An equally important number of advances are taking place in fundamental and applied issues of nonlinear optics when metasurfaces are used either standalone or in combination with other materials.
One example is record second order nonlinearities that are obtained when metallic metasurfaces are coupled with resonant electronic transitions in semiconductor heterostructures such as intersubband transitions. Additionally, since the nonlinear unit in this case is a single resonator coupled to the semiconductor heterostructure, additional functionality can be obtained at the second harmonic beam. These phenomena can be described as a phased-array source. Using this principle, we have created beam and polarization splitters operating at the second harmonic wavelength. This is new functionality that has no counterpart in conventional nonlinear optical materials.
Another interesting case arises when all-dielectric metasurfaces are made from different semiconductors and their heterostructures, that have intrinsically high optical nonlinearities. We observe record high second and third optical nonlinearities and interesting polarization selection rules that can only be explained by the large surface to volume ratio present in top-down fabricated nanoscale resonators. Additionally, the use of direct bandgap semiconductors as the constituent material for these all-dielectric metasurfaces enables the possibility for a new class of all optical switching devices that can potentially use lower energy than existing counterparts.
3:00 PM - ED10.2.02
Bimodal Phase-Matching in Nonlinear Photonic-Plasmonic Waveguides
Taiki Hatakeyama 1 , Alessandro Salandrino 2 , Kevin O'Brien 1 , Yuan Wang 1 , Xiang Zhang 1
1 , University of California, Berkeley, Berkeley, California, United States, 2 , University of Kansas, Lawrence, Kansas, United States
Show AbstractNanostructured media and metamaterials have enabled novel classical nonlinear optics such as phase-matching in a compact device, which is difficult to achieve in natural crystals. Here we present the concept of bimodal phase-matching of the second harmonic generation in hybrid photonic-plasmonic waveguides. The device has an array of plasmonic nanobars embedded in a dielectric waveguide. The array of plasmonic nanobars is horizontally aligned to maximize the interaction with the first horizontally polarized waveguide mode, which propagates with a mode index n1(ω). The pump field at the fundamental frequency ω propagates in the fundamental mode of the waveguide and excites the dipolar mode of the embedded plasmonic nanobars. The mechanism of the frequency conversion is the surface nonlinearity of the plasmonic bars. The second harmonic response of the bar is quadrupolar, while the linear scattering of the bar is dipolar. This fact can be understood from the distribution of nonlinear polarization currents. The nonlinear polarization currents are excited by the local fields at the pump wavelength through the surface nonlinear susceptibility at the metallic interfaces. The main contributions to the second harmonic currents are antiparallel and concentrated at the edges of the nanobars, which results in a quadrupolar second harmonic pattern. By symmetry the second harmonic radiation at 2ω by these currents is completely decoupled from the waveguide fundamental mode, but can efficiently excite one of the higher order antisymmetric waveguide modes with the mode index n2(2ω). The condition of perfect phase matching can be obtained if the dimensions of the waveguide are designed such that n1(ω)=n2(2ω). When the condition is satisfied, the second harmonic contributions of the quadrupolar emission from each plasmonic element couple to the second mode and add up in phase in the propagation direction. We also experimentally demonstrated the bimodal phase-matched second harmonic generation. The waveguide was made of silicon nitride deposited by PECVD. The gold nanobars were placed in the middle of the waveguide. In order to get the perfect phase-matching, the waveguide was suspended by etching the silicon substrate in KOH. The length, width, and thickness of the waveguide were 10 µm, 400 nm, and 800 nm, respectively. We measured the second harmonic generation by shining the light onto the input grating. The second harmonic signal was generated in the middle of the waveguide, which had gold nanobars, and the signal was collected at the output grating. The wavelength of the pump beam was 1.3 µm. The spectrally resolved nonlinear emission of the output signal showed the coherent second harmonic peak at 650nm superimposed with two-photon and multi-photon luminescence signals. Our approach can pave the way to the realization of novel ultracompact nonlinear optical devices harnessing the nonlinear properties of hybrid photonic-plasmonic systems.
3:15 PM - *ED10.2.03
Surface Plasmon Enhanced Optoelectronics
Pierre Berini 1 2 3
1 School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, Ontario, Canada, 2 Physics, University of Ottawa, Ottawa, Ontario, Canada, 3 Centre for Research in Photonics, University of Ottawa, Ottawa, Ontario, Canada
Show AbstractMetallic nanostructures such as optical antennas and sub-wavelength gratings can be designed to operate efficiently as coupling structures for incident optical beams to surface plasmon polaritons (SPPs) propagating thereon. On a semiconductor, nanostructures such as these can act simultaneously as a device electrode while ensuring strong optical field overlap with the active region. Additionally, SPP fields can be confined to sub-wavelength dimensions and significantly enhanced relative to the exciting field. These features are very attractive for nanoscale optoelectronic devices such as photodetectors and modulators as the excitation of SPPs alters conventional trade-offs between responsivity and speed, or modulation and speed, respectively. This is due to the facts that sub-wavelength confinement enables the active region to be shrunk to nano-scale dimensions yet good optoelectronic performance can be maintained due to the SPP field enhancement. In this paper we discuss recent progress on surface plasmon enhanced photodetectors and modulators, particularly recent proposals for a high-speed reflection modulator based on a metal-oxide-semiconductor capacitor structure exploiting the carrier refraction effect in Si [1,2], and for a Schottky contact sub-bandgap hot-hole infrared photodetector on p-Si [3]. Application to non-contact Si CMOS electronic wafer testing will be discussed.
References:
[1] S. Hassan, E. Lisicka-Skrzek, A. Olivieri, R. N. Tait and P. Berini, “Fabrication of a Plasmonic Modulator Incorporating an Overlaid Grating Coupler,” Nanotechnology, Vol. 25, 495202, 2014.
[2] A. Olivieri, C. Chen, S. Hassan, E. Lisicka-Skrzek, R. N. Tait, P. Berini, “Plasmonic nanostructured metal-oxide-semiconductor reflection modulators,” Nano Letters, Vol. 15, 2304, 2015.
[3] M. Alavirad, A. Olivieri, L. Roy, P. Berini, “High-responsivity sub-bandgap hot-hole plasmonic Schottky detectors,” Optics Express, Vol. 24, 22544, 2016.
3:45 PM - ED10.2.04
Hot Electron Enhanced Thermionic Emission (HEETE) Converters for All-Metal Optical Power Generation
Matthew Sheldon 1
1 Chemistry, Texas A&M University, College Station, Texas, United States
Show AbstractWe report on our initial studies of photo-induced charge transport from metal nanostructures. In particular, we outline how the remarkable thermal and optical energy concentration provided by plasmonic resonances can enable a new thermodynamic power cycle whereby photo-excited ‘hot’ electrons and resonant photothermal heating provides a dual excitation mechanism for electron emission. Because this process is closely related to purely thermionic emission, we label an optical power-converting device based on this mechanism a Hot Electron Enhanced Thermionic Emission (HEETE) converter. The strong enhancement of both thermal and optical energy channels, may enable a significantly more efficient strategy for optical power conversion, and one that can theoretically out-perform traditional semiconductor-based solar sells.
Our study emphasizes theoretical and experimental development of refined models for electronic distributions in metals, specifically when characteristic structural features are smaller than the mean free path of excited carriers. In addition, we have developed a mechanistic model of the photo-thermal response of optimized plasmonic absorbers accounting for factors such as spectral width of absorbance and emissivity, as well the role of thermal damping pathways such as conduction and convection. When radiative loss is the dominant cooling mechanism, as can be achieved with thermionic devices in vacuum, we anticipate solar-induced temperature increases over 900 K without additional optical concentration, and consequent photo-induced current densities with 10^15 enhancement compared with purely thermionic emission at the equivalent temperature. The optimal structures to achieve these temperatures have high absorption ( > 90% ) with spectral bandwidth that spans the visible up to 1100 nm, and emissivity of ~2% throughout the infrared. We show a variety of noble metal nanostructures (Au, Ag, Cu), and high melting point metals (W, Ir, Pt), combined with refractory dielectric cladding that can provide these ideal optoelectronic properties due to their thermal tolerance, highly absorbing and tunable plasmon resonances in the visible, and naturally low emissivity in the infrared. In combination with full-wave optical simulations that guide optimized designs, we have fabricated HEETE device test structures and measured the spectral and temperature performance, outlining opportunities for efficient power conversion.
ED10.3: Plasmonic Lasers
Session Chairs
Viktoriia Babicheva
Mark Stockman
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 131 B
4:30 PM - ED10.3.01
Organo-Lead Halide Perovskite Plasmonic Nanolaser
Yu-Jung Lu 1 , Jing-Shun Huang 1 , Wei-Hsiang Lin 1 , Harry Atwater 1
1 , California Institute of Technology, Pasadena, California, United States
Show Abstract
One of the main obstacles limiting potential applications of semiconductor nanolasers is the high threshold carrier density required for lasing, which makes them difficult to realize electrically driven lasing and integrate into optoelectronic devices. Organo-lead halide perovskite materials have recently received considerable attention for achieving a economic and tunable diode laser, owing to the use of solution-processable materials and the exceptional optical attributes of long carrier lifetimes and diffusion lengths, high fluorescence quantum yields, wavelength tenability and high optical gain coefficients1 (>104 cm−1). However, reducing the volume of such lasers to the nanoscale is the challenge nanophotonics, with potential applications in arrays of ultra-compact lasers on a chip.
In this work, we demonstrate room temperature operation of organo-lead halide perovskite nanodisk plasmonic lasers consisting of a formamidinium lead mixed-halide perovskite film active layers on ultrathin spacer layers consisting of a CVD grown boron nitride (BN) thin film on top of an atomic smooth template-stripped Au films. Perovskite nanodisk laser cavities were defined by focus ion beam (FIB) milling. Electromagnetic mode calculations indicate that the field was tightly confined in the dielectric space layer due to its relatively low refractive index. In the experiments, we observed a spectrally non-uniform mode spacing, which indicates the lasing modes arise from the plasmonic cavity instead of whispering gallery modes of the disk. We measured extremely low lasing thresholds (of 13 W/cm2) for perovskite nanodisk lasers with a diameter of 225 nm and a thickness of 100 nm. We further fabricated perovskite plasmonic lasers with sysmetically varying spacer dielectric layer thickness (CVD growth BN or ALD growth SiO2) and characterized the spontaneous emission rate using time-resolved photoluminescence (PL) measurements. Electromagnetic simulations indicate that a variation of coupling strength can be observed as the spacer thickness is varied.. Using power-dependent and time-resolved photoluminescence measurements, we determined the dependence of lasing threshold and spontaneous emission rate as a function on dielectric spacer thickness. We will also discuss the outlook for lead halide perovskite plasmonic nanolasers in applications including, on-chip coherent light sources for of bio-imaging, optical communication applications.
References
1. Brandon R. Sutherland and Edward H. Sargent. Nature Photonics 10, 295–302 (2016).
4:45 PM - *ED10.3.02
Colloidal-Quantum-Dot Spasers and Plasmonic Amplifiers
David Norris 1
1 , ETH Zurich, Zurich Switzerland
Show AbstractDue to their robust efficient fluorescence, colloidal quantum dots are currently used in applications such as light-emitting diodes, displays, and lasers. Consequently, when the spaser, a laser-like source of plasmons, was initially proposed, quantum dots were suggested as the ideal gain material. However, despite several spaser demonstrations, colloidal quantum dots and their advantages (tunability, solution-processability, etc.) have not yet been exploited. We will discuss a versatile class of quantum-dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We place block reflectors on ultrasmooth silver to obtain high-quality aberration-corrected plasmonic cavities. Colloidal quantum dots are then incorporated via electrohydrodynamic printing or simple drop-casting. Above specific excitation thresholds, monochromatic plasmons matching cavity modes are produced under ambient conditions. This output is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. The resulting spaser platform is deployable at different wavelengths, scales, and geometries for fundamental studies and applications.
5:15 PM - *ED10.3.03
Multi-Modal Lasing from Plasmonic Superlattices
Teri Odom 1
1 , Northwestern University, Evanston, Illinois, United States
Show AbstractBand structure engineering is critical for controlling the emission wavelengths and efficiency in electronic and photonic materials. Single band-edge states that show trapped slow light have been used as high-quality optical feedback for lasing from photonic bandgap crystals and metal-dielectric waveguides. Recently, we demonstrated that single band-edge lattice plasmons in periodic metal nanoparticle arrays could contribute to single-mode lasing at room-temperature with directional emission. However, the manipulation of more than a single band-edge mode for nanolasing has not been possible because of limited cavity designs. This talk will describe a new architecture based on plasmonic superlattices—finite-arrays of nanoparticles grouped into microscale arrays—to achieve multi-modal lasing. The underlying mechanism was found to depend on trapped slow light at both zero and non-zero wavevectors. We will discuss how the spectral separation and spatial emission angles of the lasing modes can be tuned by changing patch periodicity. Such characteristics may enable multi-frequency multiplexing and fast-processing of nanoscale coherent light for on-chip photonic integration.
5:45 PM - ED10.3.04
Ultrafast Dynamics of Lattice Plasmon Nanocavities
Weijia Wang 1 , Ankun Yang 2 , Richard Schaller 3 4 , George Schatz 1 3 , Teri Odom 1 2 3
1 Applied Physics Program, Northwestern University, Evanston, Illinois, United States, 2 Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States, 3 Department of Chemistry, Northwestern University, Evanston, Illinois, United States, 4 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractOne important criteria for designing plasmonic lasers is whether the gain can overcome the loss in the system. However, quantifying the losses of plasmonic nanocavities is not straightforward, because metallic materials are absorptive and the definition of mode volume is inadequate for the unconventional cavity modes. Lattice plasmon nanocavities sustain lasing at room temperature and provide directional and spectral control of lasing signals. In this work, we have characterized the intrinsic losses of lattice plasmon nanocavities and the ultrafast dynamics of plasmonic lasing action. In contrast with femtosecond lifetime of surface plasmons, lattice plasmons exhibited a picosecond photon lifetime, dramatically slowing down the group velocity of light and providing optical feedback for lasing action. Furthermore, we identified amplified spontaneous emission (ASE) as an energy transfer channel that competes with lasing action at high pump power. The picosecond lifetime of lattice plasmons indicated the extremely low loss in the cavities, which is promising to enhance light-matter interactions on nanoscale.
ED10.4: Poster Session I: Novel Materials—Nanostructures and Applications
Session Chairs
Viktoriia Babicheva
Pavel Ginzburg
Wednesday AM, April 19, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - ED10.4.01
Wideband Light Absorbers in the Visible by Ge2Sb2Te5 and Al Nanogratings
Weiling Dong 1 , Yimei Qiu 2 , Joel Yang 1 3 , Robert Simpson 1 , Tun Cao 2
1 , Singapore University of Technology and Design, Singapore Singapore, 2 Department of Biomedical Engineering, Dalian University of Technology, Dalian, Liaoning, China, 3 , Institute of Materials Research and Engineering, A-STAR, Singapore Singapore
Show AbstractIn this research, we experimentally compare two different structures based on Ge2Sb2Te5 films as candidates for broadband absorbers in the visible. One based on a planar Al/Ge2Sb2Te5 stacked structure, the other is based on a Ge2Sb2Te5/Al nanograting structure. The planar Al/Ge2Sb2Te5 stacked structure provides good absorptance in the near infrared but the crystalline state gives less than 60% absorptance in the visible. In contrast, Ge2Sb2Te5/Al nanograting structure shows strong absorptance in the visible by combining the plasmonic resonance of the Al nanograting with the absorbing Ge2Sb2Te5 film, with an absorptance bandwidth of 120 nm. In addition, different colours were obtained by engineering the width of the Al nanogratings. This structure has potential applications in light harvesting, sensing and tuneable filters.
9:00 PM - ED10.4.02
Refractory Plasmonic Absorber for Efficient CZTS Solar Cells
Omar Abdelraouf 1 , Nageh Allam 1
1 Energy Materials Laboratory (EML), Department of Physics, School of Sciences and Engineering, The American University in Cairo, Cairo Egypt
Show AbstractResonate refractory plasmonic and metamaterials nanostructures enable guiding, absorbing, and reflecting light at subwavelength dimensions. These structures are widely used in enhancing the performance of many photovoltaic cells. Herein, we target improving performance of planar CZTS solar cells. Cu2ZnSnS4 solar cell efficiency reached above 9% only in 2016, which enables a great room for improving efficiency of CZTS solar cells using engineered nanophotonics structures.
In this paper, we studied theoretically the effect of depositing titanium nitride (TiN) metamaterial wire grating structures on upper surface of active layer of CZTS solar cell. TiN is a promising low cost refractory plasmonics as its properties is similar to gold in the visible spectrum. Different cross section wire shapes were simulated, while tuning their dimensions, to find the optimum structure. The results showed enhancements in light absorption and overall efficiency over planar cells, which open a new route for integrating metamaterial absorber surface in CZTS solar cells. Simulations were performed using finite element method software COMSOL multiphysics in three-dimensional optical model.
9:00 PM - ED10.4.05
Scalable Energy-Tuned Plasmonic Nanoadditive Composites
Mark Griep 1 , Devon Boyne 1 , Joshua Orlicki 1
1 , US Army Research Lab, Aberdeen Proving Ground, Maryland, United States
Show AbstractThe development of plasmonic-enabled polymer composite materials with tailored optical properties and controlled additive orientation utilizing scalable manufacturing techniques is presented. Plasmonic nanomaterials, such as gold nanorods, hollow metal shells, and silver nanoplates, provide tunable optical properties from the visible to the near infrared regime that make them ideal additive materials towards functionalized polymer nanocomposites (PNC). Multiple applications require active plasmonic nanoadditives to be integrated into various polymer matrices, thus potentially subjecting them to extreme processing conditions, and require the materials retain their intrinsic plasmonic properties. Small-scale PNC fabrication techniques, such as drop-casting and spin-casting, can suffer from poor dispersity, aggregation and limited reproducibility. To address these issues and adapt engineered metal plasmonic additives towards large-scale manufacturing, we have developed highly effective methods to prepare PNCs incorporating functional nanoadditives utilizing extrusion and injection molding. The stability and thermal effects of the processing on the additives is mitigated by engineering stabilizing shells such as silica and poly-ethylene glycol. The resultant PNCs display excellent dispersity, minimal aggregation, controlled flow-induced alignment, and a high retention of the optical properties is confirmed. Localized degradation that occurs due to high temperature processing is predictable and therefore the optical properties are tailored by appropriate extinction peak selection prior to integration. Varying thermoplastics are utilized and to demonstrate the versatility of this method as it relates to different matrices and consequently a wide thermal processing range up to 350C.
Symposium Organizers
Viktoriia Babicheva, Georgia State University
Alexandra Boltasseva, Purdue University
Harald Giessen, University of Stuttgart
Pavel Ginzburg, Tel Aviv University
Symposium Support
Neaspec GmbH
NKT Photonics Inc.
ED10.5: Metasurfaces and Metamaterials
Session Chairs
Viktoriia Babicheva
Joshua Caldwell
Wednesday AM, April 19, 2017
PCC North, 100 Level, Room 131 B
9:00 AM - ED10.5.01
Gapless States in Microwave Artificial Graphene
Yulia Dautova 1 , Andrey Shytov 1 , Ian Hooper 1 , J. Roy Sambles 1 , Alastair Hibbins 1
1 , University of Exeter, Exeter United Kingdom
Show AbstractGraphene, the forefather of the 2D materials family, remains the focus of interest of various research communities, owing to its unusual band structure arising from its honeycomb lattice, resulting in a number of distinctive effects observed in this Dirac material. These include phenomena such as Klein tunneling, pseudo-magnetic fields, and the anomalous quantum Hall effect. A large number of successful projects to create and study artificial analogies of graphene for electronic, acoustic, and photonic waves have been undertaken in recent years [M. Polini et. al., Nature Nanotechnology 8, 161 (2013)]. All these systems have demonstrated the presence of Dirac crossings in their band structure.However no direct experimental observations of a Dirac dispersion in the electromagnetic modes supported by honeycomb arrays of metallic elements have been reported in the literature to the best of our knowledge.
In this work, we experimentally observe the presence of Dirac points in the dispersion of electromagnetic waves, propagating along a medium comprised of metallic rods arranged in a honeycomb lattice. We find two Dirac crossings at the K point of the hexagonal Brillouin zone, a new phenomenon that has not been observed in other artificial graphene systems. We attribute this to the presence of higher order modes of each individual rod. We confirm our findings with electromagnetic finite-element simulations, and further use modelling as a tool to predict possible manipulations of the “microwave graphene” band structure through bandgap opening at the Dirac points.
9:15 AM - *ED10.5.02
Absorbers in the Flatland—From Plasmonic Metasurfaces to 2D Materials
Koray Aydin 1
1 , Northwestern University, Evanston, Illinois, United States
Show AbstractOhmic losses in metals pose a significant challenge for plasmonic device applications. All the exciting phenomena associated with plasmonics such as subwavelength field localization, reduced wavelength, strong light-matter interactions come with a cost. Although quest for searching novel materials with manageable losses are underway, it is worth considering how one can make good use of such inherent optical losses associated with metals. Plasmonic absorbers have recently become an active area of research with huge potential in applications such as thermophotovoltaics, hot-electron devices, thermal emitters, biosensors. In this talk, I will present an overview of various plasmonic metasurface absorbers that have been developed in our group. It is indeed possible to control the bandwidth of plasmonic resonances to realize either broadband or narrowband absorbers using nanostructured materials. Combined with phase-change materials, the absorption, thus emission, spectra of metasurface absorbers can be dynamically controlled in an active manner. In addition to nanostructured plasmonic absorbers, it is also possible to obtain perfect absorbers utilizing ultrathin metallic films in Fabry-Perot cavities. Plasmonic absorbers enable strong light-matter interactions with subwavelength thicknesses. On the other hand, two-dimensional materials such as graphene, two-dimensional transition metal di-chalcogenides (2D TMDC), and black phosphorus have recently emerged as exciting electronic materials. However, these ultimate subwavelength thick materials pose a significant challenge for light-material interactions. Controlling and engineering absorption at monolayer thickness of such materials is rather difficult. In the remaining part of the talk, I will describe several routes for boosting light absorption in atomically-thin materials like black phosphorus and TMDCs for practical applications.
9:45 AM - *ED10.5.03
Recent Progress in Dielectric Metasurfaces
Uriel Levy 1 , Jonathan Bar David 1 , Noa Mazurski 1 , Boris Desiatov 1 , Xiaolong Zhu 2 , Marcus Shultz Carstensen 2 , N. Asger Mortensen 3 , Anders Kristensen 2
1 Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem Israel, 2 Department of Micro- and Nanotechnology, Technical University of Denmark, Kongens Lyngby Denmark, 3 Department of Photonics Engineering, Technical University of Denmark, Kongens Lyngby Denmark
Show AbstractIn this talk we will describe our recent results related to dielectric metasurfaces. Various mechanisms for achieving phase, amplitude and polarization control will be discussed. Polarization diversity will be shown as a useful feature of dielectric metasurfaces. We will also present mechanisms for integrating atomic media with metasurfaces for achieving tunability. Finally, We will also present recent results demonstrating advanced methods for high resolution resonant laser printing of metasurfaces.
10:15 AM - *ED10.5.04
Metamaterials for Nonlinear Optics
Anatoly Zayats 1
1 , King's College London, London United Kingdom
Show AbstractCombining plasmonic nanostructures in metamaterials allows precise engineering not only their spectral response and dispersion but also nonlinear optical response. From this point of view, hyperbolic metamaterials, in particular those based on plasmonic nanorod arrays, provide wealth of exciting opportunities in nonlinear optics offering ultrafast Kerr nonlinearity, polarization control, spontaneous emission control and many others. These properties can be designed as required at a given frequency range by controlling the effective plasma frequency of metamaterial, the field distribution associated with meta-atoms, as well as the mode structure of the metamaterial waveguides. In this talk, we will discuss experimental studies and numerical modelling of second- and third-order nonlinear optical processes in hyperbolic metamaterials and other plasmonic systems where coupling between the resonances plays important role in defining a nonlinear response. Second-harmonic generation and ultrafast Kerr-type nonlinearity originating from a free-carrier nonlinearity will be considered. Some of the examples to be discussed include ultrashort pulse propagation in metamaterials, nonlinear polarization control, nonlinear metamaterial integrated in silicon photonic circuitry and nonlinear metasurfaces providing efficient all-optical control of coherent nonlinear response.
ED10.6: Light Control with Graphene
Session Chairs
Pavel Ginzburg
Jon Schuller
Wednesday PM, April 19, 2017
PCC North, 100 Level, Room 131 B
11:15 AM - ED10.6.01
First Demonstration of Phase Tuning from a Mid-IR Graphene-Gold Metasurface Greater than 200 Degrees
Philip Hon 1 3 , Michelle Sherrott 2 , Juan Garcia 1 , Katherine Fountaine 1 3 , Samuel Ponti 1 , Victor Brar 2 , Harry Atwater 2 , Luke Sweatlock 1 3
1 , Northrop Grumman Corporation, NG Next, Redondo Beach, California, United States, 3 Resnick Sustainability Institute, California Institute of Technology, Pasadena, California, United States, 2 , California Institute of Technology, Pasadena, California, United States
Show AbstractMetasurfaces configured with subwavelength resonant structures have been proposed to provide phase discontinuities at the interface of a surface for beam engineering [1,2]. In this work, we have designed a mid-IR metasurface with active optical components for spatial control of phase, where the phase tunability is derived from graphene’s charge carrier tunable dielectric constant. The designed and fabricated metasurface is a periodic array of 1.2 μm long planar graphene-loaded gold dipoles spaced by a 50 nm graphene gap on a 500 nm SiN membrane which is terminated with a gold back reflector. The resulting gap plasmon mode defined by the graphene and gold dipole boundary conditions provides a strongly confined electric field at the graphene surface and by electrostatically gating the graphene, one can detune the resonance/phase about the designed center operating wavelength of 8.70 μm.
Measured data using a custom-built MIR Michelson interferometer from a 105μm x 105μm device for a range of biases show 215 degrees of phase shift. Antenna array theory predicts tuning up to ±40 degrees with side lobe levels below half the main beam intensity. By electrically isolating subwavelength subarrays, we will, through a custom-built, MIR reflection spectroscopy setup, be able to experimentally demonstrate a reflected beam at a desired angle. Demonstration of such a device could lead to fast tuning, fully solid-state dynamic apertures in the MIR.
[1] N.Yu, et al., Science, vol. 334. No. 6054, pp. 333-337, 2011
[2] Y. Yao et al, Nano Lett. 2014 Nov 12;14(11):6526-32
11:30 AM - ED10.6.02
Graphene-Coated Metasurface as a Tunable SERS Platform
Vrinda Thareja 1 , Mark Brongersma 1
1 , Stanford University, Stanford, California, United States
Show AbstractArtificially engineered ultra-thin planar optical components, referred to as metasurfaces, can effectively mold the spatial distribution of amplitude and phase of an incident light wave with sub-wavelength resolution. We demonstrate a graphene-coated, metallic metasurface as a robust, uniform and tunable Surface Enhanced Raman Scattering (SERS) substrate and exploit the two-dimensional nature of graphene to probe the surface-enhanced electric fields. By patterning sub-wavelength groove arrays of different sizes in the metal, we can enhance the electromagnetic fields and hence the Raman signal at precisely targeted wavelengths of light. We analyze the strengths of G and 2D Raman peaks of graphene as a function of these groove dimensions. Good agreement was attained between the experimentally observed and theoretically predicted Raman enhancement trends from these structures. Further, we quantitatively establish a link between the absorption in these arrays and the Raman signal enhancement by correlating reflection spectra with the corresponding Raman measurements as a function of the array dimensions. Simulated reflection spectra and Raman enhancement trends treating graphene as a thin conductive layer described by the Kubo formula agree well with the experimental observations. We conclude that the array dimensions required for maximum Raman enhancement lie between the dimensions causing maximum absorption at the excitation and emission wavelengths. Building a SERS platform whose effectivity can be visually inferred using absorption measurements will aid in fast and straightforward prediction of the achievable Raman enhancements. This work opens doors towards generation of what we refer to as ‘visual’ SERS devices that no longer depend on the more complex Raman measurements for detecting their potency.
11:45 AM - *ED10.6.03
Sculpting Nanosecond Laser Pulses In-Flight Using Grapheneintegrated Metasurface
Gennady Shvets 1
1 , The University of Texas at Austin, Austin, Texas, United States
Show AbstractOne of their most appealing features of graphene-integrated metasurfaces is their ability to change their optical properties on a nanosecond time scale. I will describe our experiments showing temporal reshaping of an optical pulse through its interaction with a metasurface evolving on the time scale of the pulse itself.
12:15 PM - *ED10.6.04
Probing Quantum Phenomena in Graphene by Infrared Nano-Imaging of Plasmonic Waves
Dmitri Basov 1
1 , Columbia University, New York, New York, United States
Show AbstractOptical spectroscopies are an invaluable resource for exploring electronic phenomena and lattice dynamics of new materials. Surface plasmon polaritons and other forms of hybrid light-matter polaritons provide new opportunities for advancing this line of inquiry [1]. 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 all from graphene physics: i) ultrafast dynamics of hot photo-excited electrons [2]; and ii) control of the electronic structure of graphene in moire superlattices [3].
[1] D.N. Basov, M. M. Fogler and J. Garcia de Abajo, Science, October 2016.
[2] 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)
[3] G. X. Ni, H. Wang, J. S. Wu, Z. Fei, M. D. Goldflam, F. Keilmann, B. Özyilmaz, A. H. Castro Neto, X. M. Xie, M. M. Fogler & D. N. Basov Nature Materials 14, 1217 (2015)
12:45 PM - ED10.6.05
Full Phase Control of Light Using Graphene Plasmons
Achim Woessner 1 , Yuanda Gao 2 , Iacopo Torre 3 , Mark Lundeberg 1 , Cheng Tan 2 , Kenji Watanabe 4 , Takashi Taniguchi 4 , Rainer Hillenbrand 5 , Marco Polini 3 , James Hone 2 , Frank Koppens 1
1 , The Institute of Photonic Sciences (ICFO), Barcelona Spain, 2 Department of Mechanical Engineering, Columbia University, New York, New York, United States, 3 , Istituto Italiano di Tecnologia, Genova Italy, 4 , National Institute for Materials Science, Tsukuba Japan, 5 , CIC nanoGUNE, San Sebastian Spain
Show AbstractOptical modulators are an integral part of modern telecommunication technology.[1] Recently two dimensional materials, such as graphene, have shown promising performance to outperform current technology.[2] One of the main challenges still remaining is to reduce their footprint.[1,2] Graphene plasmons are a versatile tool for integrated photonics and reducing the size of optoelectronic devices as they provide extreme sub-wavelength confinement of light while still offering a long propagation length.[3-5] Furthermore the graphene plasmon wavelength is in-situ tunable which makes graphene a unique material to be used for controllable transformation optics in two dimensions.[6] This has thus far remained a great challenge and the propagation of graphene plasmons was controlled by physical features in the graphene or by selectively exciting different plasmon modes.[3-5,7,8]
In this work we show a novel graphene plasmonic phase modulator which is able to tune the far-field light phase steplessly between 0 and 2π in-situ. With a physical footprint of only 350nm it is more than 30 times smaller than the 10.6µm free space wavelength of the light used.
The phase modulation is achieved by spatially tuning the graphene plasmon wavelength using a local split gate structure. We excite plane wave graphene plasmons at a sharp metal edge. These plasmons undergo a tunable phaseshift by propagating through the tunable carrier density landscape. We then measure and observe the light phase in the far-field and characterize the phase shift. We present a simple model based on the optical path length of light to explain our observations and to provide guidelines for designing such graphene plasmonic phase modulators.
This constitutes an essential step towards the full control of light propagation in two dimensions and ultimately towards ultra-compact graphene plasmonic phase modulators. This will be useful for high-speed telecommunications,[1,2] biosensing[9] and two dimensional transformation optics.[6]
References
[1] Liu, K., Ye, C. R., Khan, S. & Sorger, V. J. Laser Photon. Rev. 9, 172–194 (2015)
[2] Sun, Z., Martinez, A. & Wang, F. Nature Photon. 10, 227–238 (2016)
[3] Fei, Z. et al. Nature 487, 82–85 (2012).
[4] Chen, J. et al. Nature 487, 77–81 (2012).
[5] Woessner, A. et al.Nature Mater. 14, 421–425 (2015).
[6] Vakil, A. & Engheta, N. Science 332, 1291–1294 (2011).
[7] Alonso-González, P. et al. Science 344, 1369–1373 (2014).
[8] Fei, Z. et al. Nature Nanotech. 8, 821–825 (2013).
[9] Rodrigo, D. et al. Science 349, 165–168 (2015).
ED10.7: Switchable and Tunable Materials
Session Chairs
Pavel Ginzburg
Uriel Levy
Wednesday PM, April 19, 2017
PCC North, 100 Level, Room 131 B
2:30 PM - ED10.7.01
Dynamic Thermo-Optic Tuning of Infrared PbTe Mie Resonators
Jon Schuller 1 , Tomer Lewi 1 , Nikita Butakov 1 , Hayden Evans 1
1 , University of California, Santa Barbara, Santa Barbara, California, United States
Show AbstractThe ability to engineer the optical phase at subwavelength dimensions has led to metasurfaces that provide unprecedented control of electromagnetic waves. To reach their ultimate potential, metasurfaces must incorporate reconfigurable functions. The central challenge is achieving large tunability in subwavelength elements. Here, we demonstrate ultra-wide continuous and dynamic tuning of PbTe Mie resonators across a wide infrared range. Exploiting the large refractive index and thermo-optic coefficient of PbTe, we experimentally demonstrate tuning of high-Q Mie resonances by several linewidths with less than 10K change in temperature. We conclude by describing ongoing efforts to exploit these phenomena in reconfigurable nanophotonic and metasurface devices.
2:45 PM - ED10.7.02
Scalable Physical Coloration Based on Plasmonic Nanostructures
Tianyi Shen 1 , Jessica Cheng 1 , Domenico Pacifici 1
1 School of Engineering, Brown University, Providence, Rhode Island, United States
Show AbstractPhysical coloration based on plasmonic nanostructures has drawn great attention in the past few years. Compared with traditional dye- and pigment-coloration methods, physical coloration has unique advantages, such as the environmentally friendly process and resistance to the degradation under UV light and moisture. Recently, plasmonic nanostructures have helped generate subwavelength 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 demonstrate a scalable physical coloration approach based on plasmonic nanostructures that have been fabricated using nanoimprint lithography and then coated with an ultrathin semiconducting film acting as the absorbing layer (e.g. germanium or carbon). First, three dimensional finite difference time domain (3D FDTD) simulations are performed to optimize the design of nanostructure arrays combined with absorbing layers for saturated color generation. Then, dense arrays of plasmonic nanostructures (e.g., pillars and rods) are fabricated using an nanoimprint lithography. By tuning the size and periodicity of the plasmonic nanostructures, together with the thickness of absorbing layer deposited on the top surface, plasmonic resonances can be properly engineered to generate desired colors. Of great interest, plasmonic resonances at the rough AAO/Al interface also play an important role in light absorption as well as coloration. These findings may help us better understand the color generation mechanism based on plasmonic resonances and intrinsic absorbing properties of materials.
3:00 PM - ED10.7.03
Ultrafast Mid-Infrared Modulator Based on Optically Controlled Graphene Metasurface
Ali Basiri 1 , Yu Yao 1
1 School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona, United States
Show AbstractTechnological demands for manipulating various attributes of electromagnetic (EM) waves, including amplitude, phase and frequency, have intrigued enormous research studies during the recent years. Introduction of two dimensional (2D) materials has brought additional degrees of freedom to the fabrication design of optical modulators. Graphene, for example, has been illustrated as a promising candidate due to its linear and gapless dispersion relation, as well as having significant interband coupling and broadband interaction with EM waves from ultraviolet to microwave regime.
In order to extract the full potential of 2D materials in optical modulators, it is essential to dramatically enhance their interaction with incident light to compensate for their atomically-reduced thickness, along with having control over their optical properties on ultra-short time scales. Among different operation schemes, wave modulation in plasmonic structures by applying voltage bias on graphene has been proven extremely promising to address the aforementioned expectations. However, the operation bandwidth of this proposal is limited by the RC constant of the external electrical circuit. In this work, we propose and demonstrate a novel hybrid scheme to circumvent the upper limitation of modulation speed by incorporating the ultrafast carrier dynamics in photo-excited graphene with a plasmonic metasurface of nanoantenna arrays. The carrier concentration of graphene is derived out of equilibrium by a preceding ultra-short optical pump pulse which results to a corresponding change in the surface conductivity of graphene. As the optical properties of graphene change in time, the resonance wavelength of metasurface structure redshifts. This is associated with a transition from perfect absorption condition to near to complete reflection off the surface, exhibiting ultrafast strong modulation effect. Relying on this notion, we have developed a heuristic analytical model to reveal the fundamental device physics of the modulator and facilitate device design. Then we set up a complete time-domain full-wave simulation model to verify the device performance. Our theoretical and numerical study has shown that the overall modulation speed of the system is determined by the competing time constants of carrier relaxation dynamics in graphene and plasmonic damping of the metasurface structure. We have demonstrated all-optical modulators with ultrashort response time (~100 fs) and high extinction ratio (>30 dB), with a subwavelength footprint (<λ0/10) for the whole mid-infrared (MIR) wavelength range (3-12 µm).
In conclusion, our study opens up new possibilities for the next generation of optical modulators embedded in integrated photonic circuits. Moreover, further tailoring of the nanoantenna design enables covering a broad range of operational bandwidth from MIR to terahertz frequencies which are deemed challenging in conventional modulator schemes.
3:15 PM - ED10.7.04
Comparison of Different Phase-Change Materials for Mid-Infrared Antenna Resonance Frequency Tuning
Ann-Katrin Michel 1 , Matthias Wuttig 1 , Thomas Taubner 1 , Martin Lewin 1
1 1st Institute of Physics (IA), RWTH Aachen University, Aachen Germany
Show AbstractPhase-change materials (PCMs) have proven to be a well-suited platform for programmable metamaterials (MMs) in the infrared (IR) spectral range.[1,2] This is based on the large refractive index change between the amorphous and crystalline phase of PCMs accompanied by their low dielectric losses in the IR. PCMs can exist in different stoichiometries, which in turn lead to different dielectric properties.[3,4] To investigate these differences, we use thin films of three different (GeTe)-(Sb2Te3) compounds - Ge2Sb2Te5 (GST-225), Ge3Sb2Te6 (GST-326) and Ge8Sb2Te11 (GST-8211) – in combination with nanoantennas. We experimentally demonstrate an increase of the antenna resonance frequency position shift by up to 78% due to an increasing GeTe content in the compound. Furthermore, by exploiting the interplay between the lattice resonance of the array and the antenna resonance, narrower resonance peaks are realized. In turn, this leads to an increase of the tuning figure of merit of up to 67% by replacing GST-225 with GST-8211.[5] By this insight into the different stoichiometries and the related dielectric properties, the PCMs can be chosen to be best-suited for the desired optical applications, e.g. for tunable metamaterials.
[1] Q.Wang, N. I. Zheludev et al., Nat. Photon. 2016, 10, 60-65. [2] P. Li, A. Michel, M. Wuttig, T. Taubner et al. Nat. Mater. 2016, 15, 870-875. [3] A. U. Michel, T. Taubner et al. Nano Lett. 2013, 13, 3470-3475. [4] B. Gholipour, N. I. Zheludev et al. Adv. Mater. 2013, 25, 3050-3054. [5] A. U. Michel, M. Wuttig, T. Taubner in preparation
4:30 PM - ED10.7.05
Reversible Switching of Highly Confined Phonon-Polaritons with an Ultrathin Phase-Change Material
Peining Li 1 , Xiaosheng Yang 1 , Tobias Mass 1 , Julian Hanss 1 , Martin Lewin 1 , Ann-Katrin Michel 1 , Dmitry Chigrin 1 , Matthias Wuttig 1 , Thomas Taubner 1
1 Institute of Physics (IA), RWTH Aachen University, Aachen Germany
Show AbstractThe strong confinement and enhancement of light when coupled to surface waves or nanoparticles is the key for various applications in nanophotonics such as sensing, imaging or other devices that enable the manipulation of light fields. In the mid-infrared spectral range, metallic nanoantennas and materials supporting surface phonon polaritons (SPhPs) can be used as building blocks of such devices. In both cases, the optical functionality is usually only obtained at a fixed wavelength, determined by the geometric design and the material properties.
For active plasmonics, one way of tuning of nanoantenna resonances is to use an embedding medium that offers a variation of the refractive index n. We recently showed that specific phase-change materials (PCMs) [1,2] offer a huge contrast in the refractive index n due to a phase transition from amorphous to crystalline state, which can be thermally, optically or electrically triggered.
Now, we introduce Phonon-Polariton-based IR antennas made from polar dielectrics which exhibit lower losses and larger Q-values compared to metallic nanoantennas. Specifically, we employ a PCM as a switchable dielectric environment for loading the SPhPs [3]. This allows us to realize all-optical, non-volatile, and reversible switching of the SPhPs by controlling the structural phase of the PCM. We experimentally demonstrate that single nanosecond (ns) laser pulses can locally switch an ultra-thin PCM (down to 7 nm, < λ/1200) for exciting ultra-confined SPhPs (polariton wavevector kp > 70k0, k0 = 2p/λ) in quartz. This offers a new, elegant way to prepare all-dielectric, optically rewritable SPhP resonators without the need of complex fabrication methods.
Our approach of combining PCMs and SPhPs opens up new possibilities for non-volatile, rewritable and active nanophotonics, in particular for re-configurable, digital and memory metamaterials, flat optics and metasurfaces.
References
[1] A.-K. U. Michel, , D. N. Chigrin, T. W. W. Maß, K. Schönauer, M. Salinga, M. Wuttig, T. Taubner. 'Using Low-Loss Phase-Change Materials for Mid-Infrared Antenna Resonance Tuning', Nano Lett., 13, 3470 (2013).
[2] A.-K. U. Michel, P. Zalden, D. N. Chigrin, M. Wuttig, A. M. Lindenberg, T. Taubner, 'Reversible Optical Switching of Infrared Antenna Resonances with Ultrathin Phase-Change Layers Using Femtosecond Laser Pulses', ACS Phot., 1, 833 (2014).
[3] P. Li, X. Yang, T. W. W. Maß, J. Hanss, M. Lewin, A.-K. U. Michel, M. Wuttig, T. Taubner, 'Reversible Optical Switching of Highly Confined Phonon–Polaritons with an Ultrathin Phase-Change Material', Nat. Mat. 15, 870 (2016)
4:45 PM - *ED10.7.06
Reconfigurable Metasurfaces Using Phase Change Materials
Jacob Scheuer 1
1 School of Electrical Engineering, Tel-Aviv University, Tel-Aviv Israel
Show AbstractThe physics and applications of plasmonic metasurfaces at optical frequencies have been the focus of numerous studies during the last decade. These studies have resulted in applications in diverse fields ranging from spectroscopy and near-field microscopy to non-linear optics, holography, sensing and many others. The high sensitivity of nano-nanostructure performance to their dimensions and surroundings , suggests that for practical applications it is highly desired to have the ability to tune the response post-fabrication. Such ability is not only important for compensating for fabrication errors, but also for obtaining devices with larger functionality.
Here we present an approach for realizing tunable metasurfaces by utilizing the properties of VO2. More specifically, we target the application of optical phased-array antenna for electronic beam steering applications in the near-IR spectral range. The device is based on a 1D array of slot nano-antennas engraved in a thin Au film grown over VO2 layer. The tuning is obtained by inducing a temperature gradient over the device, which changes the refractive index of the VO2, and hence modifies the phase response of the elements comprising the array, by producing a thermal gradient within the underlying PCM layer. Using a 10-element array, we show that an incident beam can be steered up to with respect to the normal, by applying a gradient of less than 10°C.
5:15 PM - *ED10.7.07
Approaches towards Actively Tunable Mid- to Far-Infrared Nanophotonics
Joshua Caldwell 1 , Adam Dunkelberger 1 , Chase Ellis 1 , Virginia Wheeler 1 , Michael Mastro 1 , Marc Currie 1 , Joseph Tischler 1 , Jeffrey Owrutsky 1 , Igor Vurgaftman 1 , Chul Soo Kim 1 , Mijin Kim 1 , Mario Ancona 1
1 , U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractThe spectral range encompassing the mid- (3-8 μm) and long-wave (8-15 μm) infrared provides a wealth of information, for instance, regarding the local temperature variation and molecular vibrations. In addition, two ‘atmospheric windows’ (~3-5 and 8-12 μm) occur within these bands that open up the potential for optical communications, obscurant-free imaging, extended range signaling, and stand-off chemical sensing. However, optical components in this spectral range are less than optimal with hygroscopic and/or brittle material characteristics, are rarely compact, and have a small ratio of the photon to thermal energies. Polaritonic materials may allow these challenges to be overcome with optical components that are sub-diffractional in scale and composed of more traditional materials, and can thereby lead to new kinds of optical sources, components and detectors in these longer wavelengths of interest. Furthermore, this approach can exploit surface plasmon polaritons, typically supported by highly doped semiconductors, or surface phonon polaritions, incorporating polar dielectric and semiconductor crystals. Here we discuss general concepts and our recent data demonstrating active tuning of local polaritonic resonators, including free-carrier injection, nanoscale thickness phase-change films and ferroelectric layers. Initial results detailing potential near term applications will also be discussed, in particular demonstrating an approach towards realizing modulated IR sources based on thermal emitters.
5:45 PM - ED10.7.07
Phase Change Metamaterial Pollution Sensor
Weiling Dong 1 , Yimei Qiu 2 , Tun Cao 2 , Robert Simpson 1
1 , Singapore University of Technology and Design, Singapore Singapore, 2 Department of Biomedical Engineering, Dalian University of Technology, Dalian, Liaoning, China
Show AbstractWe demonstrate a tuneable metamaterial device for gas sensing. The transmission peak of this metamaterial is tuned to over a wide frequencies band in the mid-infrared. Upon switching of structure of the phase change chalcogenide, the transmission peak can be red-shifted by as much as 500 nm. In addition, the transmission peaks can be engineered by controlling the geometry of the metamaterial. The relatively large dimensions will enable large area production of device using fabrication tools such as nano imprinting. Compared with most other metamaterial designs that are passive and show transmission peaks at a fixed frequency, tuneable chalcogenide metamaterial-based filters will have extensive applications in sensing and colour filters.
ED10.8: Poster Session II: Novel Materials and Phenomena
Session Chairs
Viktoriia Babicheva
Pavel Ginzburg
Thursday AM, April 20, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - ED10.8.01
Counterintuitive Optical Properties of Infrared-Plasmonic Oxide Superlattices by Atomic Layer Deposition
Do-Joong Lee 1 , Carlos Bledt 1 , Yeong-Ho Cho 2 , Ki-Bum Kim 2 , Jimmy Xu 1
1 , Brown University, Providence, Rhode Island, United States, 2 , Seoul National University, Seoul Korea (the Republic of)
Show AbstractTransparent conductive oxides (TCOs) are a unique class of optical materials that is optically transparent and highly electrically conductive. Their wide optical bandgaps (> 3 eV) provide high optical transmittances to the visible lights, while their extremely high density of free electrons (> 1020 cm-3) allow metallic conductivity of 103 -104 S/cm. Beyond conventional uses in displays and photovoltaics, they also exhibit unusual plasmonic responses from near- to mid-infrared to RF frequencies. In this study, we propose a new form of TCOs, enabled by atomic layer deposition (ALD), for potential applications of infrared-plasmonic, low loss, and optically anisotropic metamaterials. Unlike conventional ‘bulk’ homogeneously doped TCOs, this new ALD-grown TCO is a superlattice of oxides interlaced periodically with atomically-thin oxide doping-layers. In the ALD-TCOs, material properties can be simply tuned by changing the number of AlOx atomic-doping layers [1], or by introducing other dopant layers, such as TiOx, InOx, and GaOx [2,3], within a host ZnO matrix. Our efforts so far have resulted in highly conductive and transparent TCOs with an electrical conductivity exceeding 2,000 S/cm, an extremely high electron density up to 7×1020 cm-3, and excellent shielding efficiency of microwaves (22 dB) [4]. Such atomic-layer doping has also been found to affect optical properties in surprising and extraordinary ways. Contrary to prediction in the Burstein-Moss theory, the measured transmission spectra showed an increase in transparency and a widening of bandgap with increasing doping concentrations even up to an ultra-heavy level. It was suggested the observed phenomena were attributed from improved crystallinity (lower loss), reduced refractive index, and anisotropic strains by the atomic-layers doping. Optical properties in both visible and infrared frequencies were further studied using spectroscopic ellipsometry. Details on the counterintuitive optical and infrared-plasmonic responses of the ALD-grown oxide superlattices will be given.
This research was supported by National Science Foundation (DMR-1408743).
[1] D.-J. Lee, H.-M. Kim, J.-Y. Kwon, H. Choi, S.-H. Kim, and K.-B. Kim, “Structural and electrical properties of atomic layer deposited Al-doped ZnO films”, Adv. Funct. Mater. 21, 448-455 (2011).
[2] D.-J. Lee, K.-J. Kim, S.-H. Kim, J.-Y. Kwon, J. Xu, and K.-B. Kim, “Atomic layer deposition of Ti-doped ZnO films with enhanced electron mobility”, J. Mater. Chem. C 1, 4761-4769 (2013).
[3] D.-J. Lee, J.-Y. Kwon, J. Kim, K.-J. Kim, Y.-H. Cho, S.-Y. Cho, S.-H. Kim, J. Xu, and K.-B. Kim, “Ultrasmooth, high electron mobility amorphous In-Zn-O films grown by atomic layer deposition”, J. Phys. Chem. C 118, 408-415 (2014).
[4] G. E. Fernandes, D.-J. Lee, J. H. Kim, K.-B. Kim, and J. Xu, “Infrared and microwave shielding of transparent Al-doped ZnO superlattice grown via atomic layer deposition”, J. Mater. Sci. 48, 2536-2542 (2013).
9:00 PM - ED10.8.02
Plasmon to Exciton Energy Conversion in a Single Nanoparticle
Natalia Kholmicheva 1 , Mikhail Zamkov 1
1 , Bowling Green State University, Bowling Green, Ohio, United States
Show AbstractOur research is focused on developing a novel paradigm for solar energy conversion in colloidal nanostructures aimed toward improving their photocatalytic activity. The proposed nanomaterial architecture is designed to funnel the solar light into the center of a composite nanoparticle via a built-in antenna. The absorbed radiation is then routed toward the exterior of the nanoparticle to drive catalytic reactions on its surface. To enable an efficient catalytic cycle, a novel type of energy transfer mechanism between the antenna and the catalyst will be employed. The proposed innovation makes use of judiciously engineered interfaces between inorganic domains of the composite nano-object to ensure a seamless transfer of the solar power across the photocatalytic system. The key innovation of the nanomaterial architecture lies in the plasmon-assisted light-harvesting scheme, which takes advantage of the strong electro-magnetic field that exists in metal nanoparticles to boost the production of excitons in the surrounding semiconductor shell. The excitation energy of the shell is then relayed to suitable oxidation/reduction catalysts on the surface. To ensure that different constituents of the composite nano-object work seamlessly, inter-domain interfaces will be grown using molecular epitaxy. Such stoichiometric bonds, either covalent or ionic, reduce the density of defect states that dissipate the excitation energy enabling a high throughput of the absorbed radiation. The catalytic nanostructures are rendered soluble, which allows combing the benefits of homogenous reactions on the surface (excellent activity and selectivity) with the facility of the heterogeneous systems to recycle the catalyst. These materials are particularly suited to drive aqueous phase reactions, including hydrogen production and environmental clean-up with enhanced reactivity under the solar flux.
9:00 PM - ED10.8.05
Purcell-Like Effect for Actively Controlled Resonant Semiconductor Nanostructures
Aaron Holsteen 1 , Soren Raza 1 , Pengyu Fan 1 , Mark Brongersma 1
1 , Stanford University, Stanford, California, United States
Show AbstractSubwavelength, high-refractive-index nanostructures support optical resonances that endow such structures with optical antenna functions. These resonances have been engineered to enhance the volumetric absorption and scattering of light in various optoelectronic devices such as photodetectors, solar cells, and light emitters. Whereas the impact of the size and geometry of dielectric optical antennas has been studied extensively, the impact of the local environment around such antennas has not been investigated in great detail. We demonstrate that, as with the Purcell effect for dipolar quantum emitters, the local environment of a dielectric antenna is as important as the intrinsic properties in determining its optical properties. More specifically, we demonstrate the frequency tuning of Mie-like optical resonances in silicon nanowires as their height above a surface is altered. We demonstrate tuning of the optical resonances across the visible spectrum and present a theoretical model that explains the observed spectral changes. This work demonstrates the importance of tailoring the local environment of nanostructures to optimize their performance for actively controlled optical device applications.
9:00 PM - ED10.8.06
Mechanically-Assembled Meta-Materials Based on Atomically-Thin Crystals
Juyoung Leem 1 , Pilgyu Kang 1 , Michael Cai Wang 1 , SungWoo Nam 1
1 , University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractMeta-material, a synthetic material with a structure such that it exhibits properties not usually found in natural materials, enables innovations in various research fields, including optics, mechanics, and electronics. This innovative concept can be extended to the thinnest materials systems in the world, i.e., two-dimensional (2D) materials, to enable new properties. Here, we report a novel strategy to mechanically self-assemble heterogeneous structures of graphene with 2D and three-dimensional (3D) topographies by a combination of a thin film cracking and buckle-delamination for higher degrees of structural complexity. Our meta-material based on graphene exhibits flat and crumpled topographies with precise control of their respective widths, enabled by our unique mechanical self-assembly process. The structural controllability was verified with optical and scanning electron microscopy and analyzed by fast Fourier transform. In addition, the 2D-3D heterogeneous structure maintains excellent material integrity, which is confirmed by Raman spectroscopy and sheet resistance measurement. The 2D-3D heterogeneous structure also exhibits high stretchability; it can be stretched up to 200% without any structural and/or electrical degradation. Furthermore, the 2D-3D heterogeneous structure with various widths demonstrate unique optical characteristics, and this suggests tunable optical properties enabled by our unique 2D-3D heterogeneous morphology. Our approach to forming 2D-3D heterogeneous graphene structures offers a unique avenue for enabling new materials properties and engineering of advanced device functions.
Symposium Organizers
Viktoriia Babicheva, Georgia State University
Alexandra Boltasseva, Purdue University
Harald Giessen, University of Stuttgart
Pavel Ginzburg, Tel Aviv University
Symposium Support
Neaspec GmbH
NKT Photonics Inc.
ED10.9: Energy Harvesting and Sensing Applications
Session Chairs
Viktoriia Babicheva
Pavel Ginzburg
Thursday AM, April 20, 2017
PCC North, 100 Level, Room 131 B
9:00 AM - ED10.9.01
Metasurface Back Reflectors for External Control over Semiconductor Nanowire Resonances
Jorik Van de Groep 1 , Mark Brongersma 1
1 , Stanford University, Stanford, California, United States
Show AbstractSemiconductor 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, spectrum and angular response, 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. Finally, by engineering the far-field interference between light scattered from the resonant mode and its image charge in the mirror, the angular response of the NW can be controlled.
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 Al contacts are used to extract photocurrent from the NW. Next, we apply a 200 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 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, wavelength, and angular response of the Si NW through accurate engineering of the metamirror pattern. These results demonstrate how metasurfaces enable nanophotonic devices with enhanced functionality.
9:15 AM - ED10.9.02
Nanogrid Made Invisible by Texture for Thin Film Solar Cells
Joop van Deelen 1 , Marco Barink 1
1 , TNO, Eindhoven Netherlands
Show AbstractMost research of metallic nanofeatures have been devoted to embedding or adding of those features in a device. We show the results of a nanotextured device designs combined with carefully placed nanogrid in order to minimize optical losses. Our FEM based optical modeling indicates that the reflection of both the layer stack and the metal is diminished by more than an order of magnitude if the metallic nanowires at the front of a device are placed into the relatively shallow crevices of the texture in such a way that the metal is not covered by the textured materials.
Impact of texture period and height was systematically investigated and complete mappings of parameter windows include nanowire widths between 25 and 300 nm. The spectra reveal dimension-specific optical features. The electric field distribution and energy density (i.e. absorption) diagrams of the texture show how the light is distributed and where it is absorbed. This analysis was done for wavelengths up to 1100 nm. It shows that light is ‘concentrated’ at the tips of the texture (depending on the size and wavelength of the light). So far this follows basic reasoning. Simultaneously, there appears to be reduction of E-field in the lower part of the texture and putting a metallic nanowire in this position has hardly any optical effect. This is the case even if the nanowire itself has a flat top surface and exposed to the front glass medium (i.e. not embedded underneath absorbers). Furthermore it was found that ‘texture height/metal width’ ratio is the primary factor that determines how much light is reflected and not so much the texture height, period or the metal width. This is the case over a wide range of texture heights and metal widths. An effective CIGS absorption over 95% was calculated and the reflection could be reduced to values below 2% using a texture for 20% surface coverage of the metal. It was also noted that the absorption in the nanowire is extremely low. This opens up exciting new ways of manufacturing nano-metal containing devices without the usual optical losses.
9:30 AM - *ED10.9.05
Dielectric and Plasmonic Platforms for Surface-Enhanced Sensing, Nanochemistry and Nonlinear Optics
Stefan Maier 1 , Emiliano Cortes 1
1 , Imperial College London, London United Kingdom
Show AbstractPlasmonic as well as dielectric nanostructures provide distinct approaches for channeling light to the nanoscale. This talk will focus on three different materials systems. Firstly, we will examine the potential of hot electron emission and more generally charge transfer in plasmonic systems, for appplications in nanoscale control over chemical reactions and surface-enhanced Raman scattering. The notion of a reactivity hot spot will be established in a metal bow tie system where we mapped reactivity sites of hot electron emission with 15 nm resolution. Additionally, the importance of charge transfer for control over the chemical enhancement of Raman scattering will be discussed, using a hybrid semiconductor-metal platform.
The second part of the talk focuses on all-dielectric systems. Here, we will present new studies on the light-confining and non-linear properties of germanium and gallium phosphide nanoantennas, focusing on the unique opportunities for energy confinement offered by the anapole mode.
10:00 AM - ED10.9.03
Suppression of Infrared Absorption in Nanostructured Metals by Controlling Faraday Inductance and Electron Path Length
Sang Eon Han 1 2 , Samuel M. Clark 1
1 Department of Chemical & Biological Engineering, University of New Mexico, Albuquerque, New Mexico, United States, 2 Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico, United States
Show AbstractNanostructured metals have been intensively studied for optical applications over the past few decades. However, the intrinsic loss of metals has limited the optical performance of the metal nanostructures in diverse applications. In particular, light concentration in metals by surface plasmons or other resonances causes substantial absorption in metals. Moreover, if the device operates over a broad band as in many photovoltaic devices, metal absorption needs to be controlled over the whole spectrum of interest and this poses a significant scientific and engineering challenge. Here, we avoid plasmonic excitations for low loss in infrared optoelectronics and investigate methods to further suppress loss in nanostructured metals. We demonstrate that parasitic absorption in metal nanostructures can be significantly reduced over a broad band by increasing the Faraday inductance and the electron path length. Surprisingly, we find that nanostructured metals, when cleverly designed, can behave almost like a vacuum with a negligible optical loss in the infrared region. For an example structure, the loss is reduced in comparison to flat films by more than an order of magnitude over most of the very broad spectrum between short and long wavelength infrared. For a photodetector structure, the fraction of absorption in the photoactive material increases by two orders of magnitude and the photoresponsivity increases by 15 times because of the selective suppression of metal absorption. Further, we investigate how the physics of loss suppression can be realized in 2-dimensionally patterned metal nanostructures. In this case, we increase the electron path length by using serpentine nanostructures. These nanostructured metals become transparent with optical loss of less than 7% in the infrared even at a large metal area fraction of 30%. The loss suppression effect in the serpentine structures far exceeds that in metal grid structures or straight wire arrays. These findings could benefit many metal-based applications that require low loss such as photovoltaics, photoconductive detectors, solar selective surfaces, infrared-transparent defrosting windows, and other metamaterials.
This talk is based on the following papers:
S. E. Han, “Suppression of infrared absorption in nanostructured metals by controlling Faraday inductance and electron path length,” Opt. Express 24, 2577-2589 (2016).
S. M. Clark and S. E. Han, “Two-dimensional metamaterial transparent metal electrodes for infrared optoelectronics,” Opt. Lett. 39, 3666-3669 (2014).
10:15 AM - ED10.9.04
Plasmonic Nanoantennas with Vertically Coupled Anisotropic Complementary Structures for Dual-Mode Infrared Molecule Sensing
Xiahui Chen 1 2 , Chu Wang 1 2 , Yu Yao 1 2 , Chao Wang 1 2 3
1 School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona, United States, 2 The Center for Photonics Innovation, Arizona State University, Tempe, Arizona, United States, 3 Biodesign Center for Molecular Design & Biomimetics, Arizona State University, Tempe, Arizona, United States
Show AbstractLocalized surface plasmon based nanoantennas have attracted considerable attentions for their design flexibility, high field enhancement, strong field localization, etc. Conventionally, nanofabricated structures with small (usually smaller than 10-50 nm) critical dimensions, such as bowtie antennas, were used to greatly enhance the coupling strength and near field intensity. However, it is very challenging to reliably fabricate such planar structures with uniform gaps, hence seriously affecting the nanoantenna performance. Here we present a vertical nanoantenna structure featuring strongly coupled complementary bar-shaped disks and apertures.
Our nanoantenna structure has the following advantages. First, our nanogap is determined by dry etching and metal deposition, thus more reliable in dimension control than e-beam lithography based nanopatterning. Second, our design has complementary and asymmetric structures that enable it to work at two distinct modes depending on light polarization along or perpendicular to bars. Three, nucleated gold particles on gap areas during metal deposition strongly enhance electric field intensity more than 5,000 times in our 40 nm vertical coupling scheme, i.e. up to two times enhancement compared to horizontally coupling with the same gap size. To evaluate the device molecule detection capability, monolayer octadecanethiol (CH3(CH2)17SH, 2.8 nm thick) molecules were self-assembled on gold surface of the antenna with 40 nm gap size. Significant resonance shifts of 135.6 nm and 94.0 nm for the two modes were observed, corresponding to a sensitivity of about 1 pm per molecule, i.e. a detection limit of 166-200 zepto mole per nanoantenna. In addition, a strong Fano-type resonance attributed to the interference between molecule fingerprint and antenna resonance was clearly detected. Four characteristic peaks were faithfully demonstrated, and the most intense CH2 asymmetry peak induced 6.3% change of reflectance (ΔR/R).
This demonstration of vertically coupled nanoantenna structure proves its high sensitivity in biochemical and molecular detection, and this concept can be widely extended to more complex structures and have potential applications in nano-optics, molecule sensing, energy harvesting, imaging, etc.
10:30 AM - ED10.9.04.5
Dual-Resonant Perfect Absorber for Detecting Multiple Molecular Fingerprints
Habibe Durmaz 1 2 , Arif Cetin 3 , Semih Korkmaz 4 , Ekin Aslan 4 , Sabri Kaya 4 , Roberto Paiella 1 , Mustafa Turkmen 4
1 , Boston University, Boston, Massachusetts, United States, 2 , Recep Tayyip Erdogan University, Rize Turkey, 3 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 4 , Erciyes University, Kayseri Turkey
Show AbstractRecent developments in nanophotonics have provided considerable progress in realization of thin composite layers that can be utilized strong absorption of incident electromagnetic radiation from microwave to visible region. When structure is manufactured in subwavelenght scale, the thin layer is generally called “perfect absorbers” (PAs). The PAs are metametarials for which a narrow frequency respond can be obtained with near-unity absorbance, which makes them an ideal candidate for surface enhanced infrared absorption (SEIRA) spectroscopy applications. Since the radiation damping is low at the infrared region, high Q-factors that lead to strong near-field could be obtained with the plasmonic resonances of the PAs.
Recent studies have demonstrated that high Q-factor is crucial for achieving large spectroscopic signals associated with the molecular vibrational modes. 2 Here we introduce a simultaneous detection of absorption signals corresponding to C=O and C–H bands of a polymethyl methacrylate (PMMA) film. We have demonstrated a PA platform in which the two bands of maximum absorption of 98% are experimentally accomplished3. Furthermore, by tuning the geometrical device parameters (i.e., spectrally tuning the plasmonic modes), the PA system maintains the amplitude and linewidth. These features are ideal for multiband surface-enhanced infrared spectroscopy applications. In addition, the coupling between plasmonic and vibrational modes, leading to splitting and anticrossing behavior within the PA absorption spectra, is determined. These results demonstrate the simultaneous identification of different molecular vibrational modes with a possibility of identifying variety of molecular species or even larger complex biological entities compared to classical SEIRA systems.
1) C. Wu et al., Nat. Mater. 11, 69 (2012)
2) K. Ataka, J. Heberle, Anal. Bioanal. Chem. 2007, 388, 47.
3) A. E. Cetin et al., Advanced Optical Materials, vol. 4, pp. 1274–1280, (2016)
10:45 AM - ED10.9.06
CMOS-Compatible Integrated Surface Enhanced Raman Scattering Sensors
Cuong Nguyen 1 , Will Thrift 1 , Qiancheng Zhao 1 , Arunima Bhattacharjee 1 , Mahsa Darvishzadeh-Varcheie 1 , Filippo Capolino 1 , Katrine Whiteson 1 , Allon Hochbaum 1 , Ozdal Boyraz 1 , Regina Ragan 1
1 , University of California, Irvine, Irvine, California, United States
Show AbstractAdvances in understanding of genomics have led to the knowledge that complex and dynamic set of molecules called metabolites can provide real-time information about a person health state. While liquid chromatography mass spectrometry (LC-MS) can measure trace levels of metabolites in biological samples at parts-per-trillion limits, they are unsuitable for commercial healthcare uses. Here, we demonstrate the integration of highly nonlinear sub-micron silicon nitride trench waveguides with Au nanoparticle oligomers as nanoantennas as a low-cost biosensor system using surface enhanced Raman scattering. The CMOS-compatible waveguides were fabricated using conventional optical lithography followed by anisotropic potassium hydroxide etching and low vapor chemical vapor deposition of silicon nitride. With an open width of 5µm, propagation loss was reported at 0.8±0.26 dB/cm. The waveguides are then patterned with phase-separated diblock copolymer thin films composed of polystyrene (PS) and poly(methylmethacrylate) (PMMA). Fabrication of optically uniform nanoantennas on the waveguides were then done using electrohydrodynamically driven chemical crosslinking to form a dense layer of 2-dimensional, small, and close-packed Au oligomers that attach to the PMMA domains. Using a monolayer of benzenethiol to benchmark the nanoantennas on fabricated on silicon, we showed an average SERS enhancement factor of 1.4x109 with SERS signal standard deviation of 10% over 1mm2 area using excitation wavelength of 785 nm. Nonlinear refractive index for waveguides integrated with nanoantennas was calculated to be 7.0917x10-19 m2/W by measuring spectral broadening caused by self-phase modulation of high-energy pulses. Additionally, we use nanoantennas fabricated on silicon to detect pyocyanin, a metabolite released by Pseudomonas Aeruginosa during biofilm formation, a biological process responsible for lung infections in cystic fibrosis patients. We demonstrated a 100 parts-per-trillion detection limit and 1 part-per-billion quantification limit with a quantification range spanning 5 orders of magnitude. With this, we showed the capability of our low-cost biosensing system in revolutionizing the way physicians make informed decisions by providing the ability to monitor bacterial metabolic activity.
11:30 AM - ED10.9.07
A Piezoplasmonic Response in Metal Nanoislands—Optical Sensing of Strain in Biological Environments Using Low-Dimensional Metamaterials
Brandon Marin 1 , Justin Liu 1 , Darren Lipomi 1
1 , University of California, San Diego, La Jolla, California, United States
Show AbstractLow–dimensional materials and their interfaces have attracted a great deal of interest over the last decade due to their extraordinary mechanical, photonic, and electronic properties. Particularly, graphene as a stand-alone 2D material has been researched extensively for its unique properties. However, its use as a low–dimensional surface template has been less explored. Recently, our group investigated graphene as a surface template for the fabrication of metal nanoislands and demonstrated control over morphology and order. This method was shown to be a robust and facile approach to creating low–dimensional metal interfaces- called “metal nanoislands”. These metal nanoislands show a high potential for interesting and unique applications in optical and electronic sensing. To this end, we demonstrate the use of these metal nanoislands for optical detection of electrically-stimulated strain in muscoskeletal cells using surface-enhanced Raman scattering (SERS). This optical response, called a “piezoplasmonic” effect, demonstrated sensitivity to strains as low as 0.03% and gauge factors as high as 1200. This platform offers a unique multi-modal platform for optoelectronic sensing, as these materials were used for both stimulus and detection of signal in biological environments.
11:45 AM - *ED10.9.08
Aluminum Plasmonics—New Wavelengths and New Versatility for Sensing Applications
Naomi Halas 1
1 , Rice University, Houston, Texas, United States
Show AbstractAluminum, the most abundant metal on earth, is a highly promising material for plasmonics with the potential for low-cost photonic technologies in the visible region of the spectrum. From sensing to photocatalysis to large-area patterned active displays, applications have recently showcased how the properties of Aluminum can be exploited to provide similar, if not superior, functionalities relative to the more traditional noble metals. For surface-enhanced spectroscopies such as SERS, we will show how the ultrathin oxide coating of chemically synthesized Al nanocrystals facilitates molecular binding that provides new detection capabilities. Al nanocrystals are ideal nanoantennas to be combined with reactive nanoparticles for modular, “antenna-reactor” complexes for photocatalysis. Our studies of Al nanocrystal growth by chemical means has led to new insight into the controlled growth chemistry of this nanoparticle.
12:15 PM - ED10.9.10
Laser Processing of Low Optical Reflection Micro/Nano-Patterned Si Substrates for SERS
Ashwani Verma 1 , Rupali Das 1 , R.K. Soni 1
1 Physics, Indian Institute of Technology Delhi, NEW DELHI, Delhi, India
Show AbstractLight collection efficiency and specific molecular detection are crucial factors for the performance of bio-chemical molecule sensors. In this paper, the low optical-reflection silicon (Si) substrates which combines reduced optical reflectivity by light trapping effect and high Raman enhancement ability of gold nanoparticles coated textured Si substrates are investigated for surface enhanced Raman scattering (SERS). A fast, single-step and highly controllable nanosecond (ns) laser processing technique is employed to fabricate textured Si substrates under ambient conditions. Parallel array of micro-pyramids are fabricated on Si surface by direct laser writing two dimensional structures. SEM micrographs clearly show well-ordered surface features in the form of micro-pyramid shape with well-defined sharp tips on the laser processed Si substrates. The aggregation of Si micro/nano-particles on Si surface forms nanocavities and nanogaps and further enhances the surface roughness in order to minimize the optical reflection. The low optical-reflection of the Si substrates exhibit optical reflection below 15% over a broad wavelength range from 300 nm to 1200 nm. The textured Si substrates with high signal reproducibility were successfully applied as SERS substrates to detect very small concentration of Rhodamine B molecules with an average enhancement factor of the order of ~105. The low optical reflection and SERS signal amplification are also altered by the variation of laser pulse energy resulting into low optical reflection and high SERS signal intensity over the entire laser-patterned area. This approach provides a novel high-speed and cost-effective method for fabricating SERS substrate with micro/nano-scale surfaces roughness and low optical reflection for high Raman signal enhancement.
12:30 PM - *ED10.9.11
Control of Light-Matter Interactions with Nonlocal Dielectric Environments
Ekembu Tanyi 1 , Vanessa Peters 1 , Srujana Prayakarao 1 , Nicholas Kotov 2 , Mikhail Noginov 1
1 Center for Materials Research, Norfolk State University, Norfolk, Virginia, United States, 2 Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States
Show AbstractInteraction of molecules and quantum dots with metallic nanostructures and nanostructured composite materials, including metamaterials, enable scores of rich physical phenomena, spanning from stimulated emission of localized [1] and propagating [2,3] surface plasmons to control of spontaneous [4] and stimulated [5] emission, Förster energy transfer [6] and van der Waals forces [7]. Many of these processes occur in the regime of weak coupling of molecular excitons and surface plasmons, which affects e.g. the rate and the directionality of spontaneous emission but not the energy positions of the molecular eigenstates. The latter control can be achieved in the regime of strong coupling of molecules with surface plasmons and cavities. Examples include control of chemical reactions [8,9], surface potential and Raman scattering. The review of the State-of-the-Art in the field [10,11] will be followed with the discussion of the novel results and phenomena stemming from both weak and strong exciton-plasmon coupling.
[1] M. A. Noginov, G. Zhu, A. M. Belgrave, R. Bakker, V. M. Shalaev, E. E. Narimanov, S. Stout, E. Herz, T. Suteewong, and U. Wiesner, “Demonstration of a spaser-based nanolaser“, Nature 460, 1110-1112 (2009). Virtual Journal of Nanoscale Science & Technology (2009).
[2] M. A. Noginov, G. Zhu, M. Mayy, B. A. Ritzo, N. Noginova, and V. A. Podolskiy, “Stimulated emission of surface plasmon polaritons”, Phys. Rev. Lett. 101, 226806 (2008). Editor’s Choice.
[3] J. K. Kitur, V. A. Podolskiy and M. A. Noginov, “Stimulated emission of surface plasmon polaritons in microcylinder cavity”, Phys. Rev. Lett. 106, 183903 (2011).
[4] M. A. Noginov, H. Li, Yu. A. Barnakov, D. Dryden, G. Nataraj, G. Zhu, C. E. Bonner, M. Mayy, Z. Jacob, E. E. Narimanov, “Controlling spontaneous emission with metamaterials”, Opt. Lett. 35, 1863-1865 (2010).
[5] J. K. Kitur, L. Gu, T. Tumkur, C. Bonner, and M. A. Noginov, “Stimulated emission of surface plasmons on top of metamaterials with hyperbolic dispersion”, ACS Photonics (2015), DOI: 10.1021/ph500475x.
[6] T. Tumkur, J. Kitur, C. Bonner, A. Poddubny, E. Narimanov and M. Noginov, “Control of Förster energy transfer in vicinity of metallic surfaces and hyperbolic metamaterials”, Faraday Discussions 178, 395-412 (2015).
[7] Yu. A. Barnakov, D. A. Adnew, T. Tumkur, V. I. Gavrilenko, C. E. Bonner, E. E. Narimanov, M. A. Noginov, “Control of wetting with hyperbolic metamaterials and metallic films”, in CLEO: 2013 (Optical Society of America, Washington, DC, 2013), presentation number QTu2A.3.
[8] J. A. Hutchison, T. Schwartz, C. Genet, E. Devaux, & T. W. Ebbesen, Angew. Chem. Int. Ed. 51, 1592–1596 (2012).
[9] A. F. i Morral and F. Stellacci, “Ultrastrong routes to new chemistry”, Nature Materials 11, 272-273 (2012).
[10] Lee, J.; Govorov, A.O.; Kotov, N.A. Bioconjugated Superstructures of CdTe Nanowires and Nanoparticles: Multistep Cascade Förster Resonance Energy Transfer and Energy Channeling. Nano Lett. 2005, 5(10), 2063–2069.
ED10.10: Plasmonics and Metamaterials Applications
Session Chairs
Viktoriia Babicheva
Wenshan Cai
Thursday PM, April 20, 2017
PCC North, 100 Level, Room 131 B
2:30 PM - ED10.10.01
Plasmonic Transition Metal Nitrides for Harsh-Environment Applications
Urcan Guler 1 , Harsha Reddy 1 , K. Chaudhuri 1 , Alberto Naldoni 1 , Alexander Kildishev 1 , Vladimir Shalaev 1 , Alexandra Boltasseva 1
1 , Purdue University, West Lafayette, Indiana, United States
Show AbstractTransition metal nitrides exhibit plasmonic properties in the visible and near infrared regions of the electromagnetic spectrum together with refractory properties. Titanium nitride (TiN) has been studied extensively as a refractory plasmonic material for use in applications that impose harsh environmental conditions. In this talk, we will present our recent results with spectrally selective emitters and sensors based on refractory metamaterials. Potential use of TiN nanoparticles in plasmon-enhanced photocatalysis will be discussed with initial experimental results showing enhanced performance compared to identical systems with gold nanoparticles. Alternative fabrication techniques, such as nitridation of titania under ammonia flow, will be presented. Initial results show that it is possible to fabricate complex nanostructures of TiN utilizing the well-known material synthesis of titania. In addition, zirconium nitride (ZrN) will be presented as an alternative transition metal nitride with relatively lower loss compared to TiN. High temperature characterization of plasmonic materials will also be discussed. Temperature dependence of the dielectric permittivity is studied via a customized variable angle spectroscopic ellipsometry setup where thin films of transition metal nitrides and noble metals are characterized in detail.
2:45 PM - ED10.10.02
Temperature and Phase Transition Sensing in Liquids with Fluorescent Probes
Ivan Shishkin 1 2 , Tmiron Alon 1 , Ronen Dagan 1 , Pavel Ginzburg 1 2
1 , Tel Aviv University, Ramat Aviv Israel, 2 , ITMO, St. Petersburg Russian Federation
Show AbstractLocal environment of fluorescent dyes could strongly affect emission dynamics of the latter. In particular, both signal intensities and emission lifetimes are highly sensitive to solvent temperatures. Here, temperature-dependent behavior Rhodamine B fluorescence in water and ethanol solutions was experimentally investigated. Phase transition point between liquid water and ice was shown to have a dramatic impact on both in intensity (30-fold drop) and in lifetime (from 2.68 ns down to 0.13 ns) of the dye luminescence along with the shift of spectral maxima from 590 to 625 nm. At the same time, ethanol solvent does not lead any similar behavior. A dramatic drop both in intensity and lifetime in case of aqueous solution could be considered as sensitive probe for phase transition in water. Nanostructures, such as plasmonic metasurfaces and metamaterials, could enhance the responsivities furthermore, as will be shown in this contribution. From the fundamental stand-point, the reported results and approaches enable further investigations of dye-solvent interactions and studies of physical properties of liquids at phase transition points. Application-wise, properly chosen fluorescent tags could enable efficient monitoring of dynamical processes in liquid solutions. - arxiv:1609.09284
3:00 PM - ED10.10.03
Scalably Manufactured Metamaterial for Effective Day-Time Radiative Cooling
Yao Zhai 1 , Yaoguang Ma 1 , Sabrina David 1 , Dongliang Zhao 1 , Runnan Lou 1 , Chuanwei Wu 1 , Ronggui Yang 1 , Xiaobo Yin 1
1 , University of Colorado Boulder, Boulder, Colorado, United States
Show AbstractPassive radiative cooling draws heat from a room-temperature object’s surface and radiates it into cold sky in form of infrared radiation to which the atmosphere is transparent. Nanophotonic structures that fully reflect solar irradiance while emit strongly infrared radiation were recently introduced for effective day-time radiative cooling[1-3]. Given the intrinsic low power density of emitted infrared radiation, however, practical radiative cooling applications demand scalable manufacturing capability of these judiciously designed photonic structures. Recently we have developed a scalably manufactured metamaterial for effective radiative cooling using a random glass-polymer metamaterial, achieving an infrared emissivity greater than 0.93 across the entire atmospheric window while being fully transparent to the solar spectrum, approaching the theoretical limit for day-time radiative cooling. The 300-mm-wide metamaterial was fabricated with a roll-to-roll process at a 5-meter-per-minute output rate. The noon-time (11am – 2pm) radiative cooling effect has been demonstrated with an average cooling power of 93 W/m2 under direct sunshine during a continuous three-day field test. The 72-hr average cooling power is greater than 110 W/m2. The scalably manufactured metamaterial shows its potentials in large scale cooling applications, such as cooling roof and cooling solar cell panels to improve solar cell efficiency.
References
[1] E. Rephaeli, A. Raman, and S. Fan, Ultrabroadband photonic structures to achieve high-performance daytime radiative cooling, Nano Letters, 13, 1457 (2013).
[2] A. P. Raman, M. A. Anoma, L. Zhu, E. Rephaeli, and S. Fan, Passive radiative cooling below ambient air temperature under direct sunlight, Nature, 515, 540 (2014).
[3] Md. M. Hossain, M. Gu, Radiative Cooling: Principles, Progress, and Potentials, Adv. Sci., 4, 1500360 (2016).
3:15 PM - ED10.10.04
Metaplatforms for Analog Computing
Brian Edwards 1 , Nasim Mohammadi Estakhri 1 , Nader Engheta 1
1 , University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractThe recently proposed concept of metamaterial-based analog computing [Silva et al. Science 343 (2014)] opened up an intriguing possibility to perform mathematical operations by tailoring the light-matter interactions at the nanoscale. As the light propagates through such structure, the "operator" layout is carefully designed to gradually modify the profile of the impinging beam and accomplish various functionalities such as differentiation, integration, and convolution. In the present work we explore the possibility of using material-based metastructures for light-based signal processing to find solutions to various equation systems, including the scenarios of translationally-variant differential and integral equations. While these equations are generally solved using numerical methods, contrary to the previous proposals to employ light as a computational tool, here using proper material design we create a proper feedback mechanism through a set of waveguides, allowing the light to physically recurse through a kernel. The kernel then has a more complicated relationship with the output than can be easily achieved through traditional means. We numerically demonstrate several kernel designs that compute the solutions to different equations. We envision that our results will lead to fully-analog, light-based, ultrafast equation-solving machines.
3:30 PM - ED10.10.05
Polarization-Resolved Spectroscopy Using Multiresonant Plasmonic Bull’s-Eye Antennas
Eva De Leo 1 , Ario Cocina 1 , Boris le Feber 1 , Ferry Prins 1 , David Norris 1
1 , ETH Zurich, Zurich Switzerland
Show AbstractPlasmonic antennas are able to confine electromagnetic fields at the nanoscale as well as shape the far-field pattern of coupled emitters. Specifically, careful design of these nanostructures allows enhanced in- and out-coupling of light for targeted wavelengths or propagation directions. Moreover, the ability to control both the polarization-dependent response of the plasmonic antenna and the polarization state of the outgoing light, offers an effective strategy to manipulate electromagnetic fields [1], [2]. Thanks to these properties, optical nanoantennas represent a powerful tool in a wide range of applications including optical imaging, light harvesting, and sensing [3].
One of the most successful examples of plasmonic antennas are the so-called bull’s eye apertures [4-6]. Using concentric circular grooves around a central subwavelength hole, these single-resonant structures provide spectrally selective and directional transmission of light [4,5]. Here, inspired by these structures, we introduce a new class of plasmonic bull’s eye antennas, consisting of concentric polygons [7]. In contrast to the traditional circular bull’s eyes, our polygonal bull’s eyes can accommodate multiple resonances by introducing variations in the periodicity along the different axes of the structure. Moreover, the resonant color associated with each axis will acquire a unique linear polarization imposed by the axis orientation.
We experimentally demonstrate that the resonance wavelengths of our structures can indeed be directly mapped to the transmitted polarization. Furthermore, by measuring the emission direction of these multi-resonant bull’s eyes, we demonstrate wavelength dependent optical beaming. From these observations, that we support with far-field simulations, we will work toward polarimetric applications that may enable increased sensitivity and selectivity in plasmonic sensing.
References
[1] C. Osorio et al., Scientific Reports 5, 9966 (2015)
[2] F. Afshinmanesh et al., Nanophotonics 1, 125 (2012)
[3] L. Novotny et al., Nature Photonics 5, 83 (2011)
[4] H.J. Lezec et al., Science 297, 820–822 (2002)
[5] J. Schuller et al., Nature Materials 9, 193 (2010)
[6] S. Han et al., Physical Review Letters 104, 043901 (2010)
[7] E. De Leo et al., in preparation (2016)
ED10.11: Optical Phenomena in Metasurfaces and Nanostructures
Session Chairs
Yohannes Abate
Pavel Ginzburg
Thursday PM, April 20, 2017
PCC North, 100 Level, Room 131 B
4:15 PM - ED10.11.01
Ultra-Light Subwavelength-Thickness Emissive Metaphotonic Structures for Thermal Radiation Management
Samuel Loke 1 , Ali Naqavi 1 , Dennis Callahan 1 , Michael Kelzenberg 1 , Pilar Espinet 1 , Emily Warmann 1 , Tatiana Vingoradova 2 , Alexander Messer 2 , Tatiana Roy 1 , Harry Atwater 1
1 , California Institute of Technology, Pasadena, California, United States, 2 , Northrop Grumman Corporation, Azusa, California, United States
Show AbstractA major challenge in designing thermal radiation management structures for spacecraft, aircraft and space power systems is the development of ultralight, flexible structures with emissivity control in the 8–14 micron wavelength range, required for rejection of the generated heat. Here we report the design, fabrication and characterization of ultralight metaphotonic structures with subwavelength thickness for emission of thermal radiation. These structures weigh only 2–7 g/m2, are easy to fabricate, and provide high emissivity over a very wide spectral range, from 5-30 micron in wavelength, for angles up to 60 degrees. Furthermore, the materials that we use in our structures are suitable for use in space applications.
Our designs are layered planar heterostructure laminates of ultrathin (thickness less than optical skin depth) metals and wavelength-scale thickness dielectric layers that exploit the absorption-emission reciprocity of Kirchhoff’s thermal radiation law. Our simplest heterostructure consists of a metallic back reflector, an optically transparent quarter-wavelength layer and a thin metallic sheet, from bottom to top, similar to a Salisbury screen [1]. A high emissivity can be obtained for this structure from design that impedance matches the heterostructure to free space, by varying the thicknesses of the dielectric and metallic layers. Adding to this structure an additional quarter-wavelength transparent layer and thin metallic sheet lead to higher performance heterostructures. Suitably chosen layer thicknesses lead to emissivity values of 65 % and 85 % for the first and the second heterostructures, respectively. Notably, the total thickness of these structures is in the range of λ/5 – λ/2 in units of free space wavelength at the peak wavelength of the blackbody spectrum at 300°K. The increased emissivity of the latter structure is attributed to the better impedance matching to free space. Finally, we designed a third class of emissive structures that feature subwavelength trapezoidal texturing on top of the basic planar structure. For the optimized structure, we find emissivity values as high as 90 %. The very high emissivity of this structure is attributed to its broadband resonant behavior due to the tapered coupler shape.
We fabricated experimental structures by spinning of thin film polyimide layers on Cr-coated Si substrates, followed by electron beam evaporation of Cr and SiO2. The thickness of each polyimide layer is close to 2 microns, so the total structure thickness is smaller than λ/2. Our measurements indicate an emissivity of 70 % and 87 % for the planar structures with one and two transparent layers. We will report results of ongoing simulations and fabrication efforts seeking to achieve even higher emissivity at lower areal mass.
[1] W. W. Salisbury, U.S. Patent No. 2 599 944 (1952).
4:30 PM - ED10.11.02
Silicon Nanoantennas for Highly Directional Light Emission from Monolayer MoS2
Ahmet Fatih Cihan 1 , Alberto Curto 1 , Soren Raza 1 , Mark Brongersma 1
1 , Stanford University, Stanford, California, United States
Show AbstractControlling the direction of light from quantum emitters has important applications ranging from nanoscale single-photon sources to macroscale lighting and displays. High-refractive index semiconductor antennas have emerged as promising tools for such directionality of light at the nanoscale. They support electric and magnetic resonances that can result in directional interference by satisfying the so-called Kerker conditions for plane wave scattering. Going beyond passive far-field scattering, tuning the interference of antenna modes with emitter dipoles in an active light-emitting material can offer highly directional emission. Here, we experimentally demonstrate and theoretically analyze a more than 25-fold forward-to-backward ratio of visible light emission from dipole sources in monolayer MoS2 coupled to Si nanowire antennas for TM excitation. Within the operation regime of our nanowires, we observe such strong directionality in emission as a result of the interference between the source dipole and the excited electric dipole in the antenna. Our theoretical and analytical results suggest that there may be multiple different directionality methods for the nanowire geometry. The demonstrated directionality of visible light emission with dielectric antennas can have broad applications in nanophotonics, lighting and displays.
4:45 PM - *ED10.11.03
Magnetic Resonant Effects in High-Index Dielectric Nanostructures and Metasurfaces
Arseniy Kuznetsov 1 , Ramon Paniagua-Dominguez 1 , Ye Feng Yu 1 , Hanfang Hao 1 , Egor Khaidarov 1 , Yuan Hsing Fu 1 , Boris Luk'yanchuk 1
1 , Data Storage Institute, Singapore Singapore
Show AbstractOptical magnetism has long been one of the major goals for metamaterial community. With plasmonic components, achieving of strong magnetic response is challenging in the visible part of the spectrum. Even though some particular particle geometries, such as split-ring resonators, can have a measurable magnetic response it is still typically much weaker than associated electric response of the same nanostructures at the same frequency. This, together with high Ohmic losses, makes observation of magnetic effects with resonant plasmonic nanostructures difficult. Recently high-index dielectric nanostructures have been proposed as a low-loss alternative to plasmonics to achieve strong resonances in the visible and IR spectral ranges [1]. In contrast to plasmonics, high-index dielectric nanostructures may have a strong resonant magnetic response even for simple nanoparticle geometries due to the field penetration and phase retardation inside the particles. This, together with inherently low losses of some dielectric materials, makes it possible to observe completely new effects and optical phenomena arising due to magnetic response and its interference with electric response in the same nanostructures.
In this talk, we will review our recent experimental observation of several new effects related to this electric-magnetic resonance interference. One of them is so-called first Kerker’s condition when dielectric nanoparticles act as Huygens’ sources scattering light only into forward direction with no scattering backward [2]. This property can be applied to design high-efficiency transmissive Huygens’ metasurfaces for wavefront control [3]. Another example is generalized Brewster effect in dielectric metasurfaces which appears as a result of interference of electric and magnetic dipole resonances and cancellation of their scattering under specific angles [4]. In contrast to conventional Brewster effect, the generalized effect can be obtained for any angle and polarization of choice. Finally we will show how control of scattering resonances in dielectric nanoparticles may help to achieve light bending at extra-high angles.
References
[1] A. I. Kuznetsov, A. E. Miroshnichenko, M. L. Brongersma, Y. S. Kivshar, B. Luk’yanchuk, "Optically resonant dielectric nanostructures," Science (2016), in press.
[2] Y. H. Fu, A. I. Kuznetsov, A. E. Miroshnichenko, Y. F. Yu, B. Luk’yanchuk, Directional visible light scattering by silicon nanoparticles. Nature Comm. 4, 1527 (2013).
[3] Y. F. Yu, A. Y. Zhu, R. Paniagua-Domínguez, Y. H. Fu, B. Luk’yanchuk, A. I. Kuznetsov, "High-transmission dielectric metasurface with 2π phase control at visible wavelengths," Laser Photon. Rev. 9, 412 (2015).
[4] R. Paniagua-Domínguez, Y. F. Yu, A. E. Miroschnichenko, L. A. Krivitsky, Y. H. Fu, V. Valuckas, L. Gonzaga, Y. T. Toh, A. Y. S. Kay, B. Luk’yanchuk, A. I. Kuznetsov, "Generalized Brewster effect in dielectric metasurfaces," Nat. Commun. 7, 10362 (2016).
5:15 PM - *ED10.11.04
Nanoimaging of IR and THz Polaritons in 2D Materials
Rainer Hillenbrand 1
1 , CIC nanoGUNE, San Sebastian Spain
Show AbstractA promising solution for active control of light on the nanometer scale are plasmons in graphene, which offer ultra-short wavelengths, long lifetimes, strong field confinement, and tuning possibilities by electrical gating. Here, we discuss scattering-type scanning near-field optical microscopy (s-SNOM) for real-space imaging of infrared plasmons in graphene nanoresonators [1]. We also introduce THz near-field photocurrent nanoscopy based on s-SNOM, and discuss its application for imaging acoustic graphene plasmons in a graphene-based THz detector [2]. Further, we study the propagation of hyperbolic phonon polaritons in boron nitride nanostructures, which is governed by positive and negative phase velocities, as well as by group velocities as small as 0.002c [3].
[1] A. Nikitin, et al., Nat. Photon. 10, 239 (2016)
[2] P. Alonso-González et al., arXiv: 1601.05753
[3] E. Yoxall, et al., Nat. Photon. 9, 674 (2015)
5:45 PM - ED10.11.05
Near-Field Edge Fringes in Nanolayer Materials
Viktoriia Babicheva 1 , Vladislav Yakovlev 2 1 , Sampath Gamage 1 , Mark Stockman 1 , Yohannes Abate 1
1 , Georgia State University, Atlanta, Georgia, United States, 2 , Ludwig Maximilians University of Munich, Munich Germany
Show AbstractScattering type near-field optical microscope (s-SNOM) breaks the diffraction limit by employing a tip with an apex radius of ~20 nm, much smaller than the excitation wavelength. s-SNOM provides optical, chemical, and structural information of a surface enabling its imaging with nanoscale resolution. Here, we investigate nanolayers of materials with different permittivities and demonstrate an approach to identify material type based on near fields at sample edges.
To characterize near-field properties of different structures, we developed a theoretical approach that allows for calculations of s-SNOM response. In contrast to previous models where the effective polarizability of the tip in the presence of a sample was evaluated in semi-analytical point-dipole or finite-dipole approximations, our model relies on evaluation of the tip-sample polarizability numerically found using frequency-domain solver of CST Microwave Studio. Thus, we fully consider the tip-sample near-field interaction, and our model is applicable to any sample (not just thin films) without any fitting parameters. In this model, the whole conical shape of the illuminated tip is considered, and the full structure of the sample, including the various layers of the substrate, is fully accounted for to simulate the experiment [1].
Using this model, we have found that metallic edge has bright and dark fringes in near-field characterization [2], whereas an edge of dielectric material has no outside fringe. Similar behavior is observed for anisotropic material with hyperbolic dispersion, e.g. boron nitride in mid-IR range: depending on the wavelength, boron nitride shows either metal or dielectric optical properties.
[1] Y. Abate, D. Seidlitz, A. Fali, S. Gamage, V. Babicheva, V. Yakovlev, M. Stockman, R. Collazo, D. Alden, N. Dietz, “Nanoscopy of Phase Separation in InxGa1-xN Alloys,” ACS Applied Materials & Interfaces 8, 23160–23166 (2016).
[2] Y. Abate, S. Gamage, L. Zhen, S.B. Cronin, H. Wang, V. Babicheva, M.H. Javani, M.I. Stockman, “Nanoscopy reveals surface-metallic black phosphorus,” Light: Science & Applications, accepted, 2016, doi: 10.1038/lsa.2016.162
ED10.12: Poster Session III: Plasmonic Materials for Sensing
Session Chairs
Friday AM, April 21, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - ED10.12.03
Nitride-Based Surface Plasmon Resonance Biosensors
Kun-Yu Lai 1 , Fan-Ching Chien 1
1 , National Central University, Chung-Li Taiwan
Show AbstractComparing with conventional techniques, surface plasmon resonance (SPR) biosensors allow label-free, wash-free, multi-analyte and real-time measurement, greatly expediting the assay process. However, most of the current SPR biosensors are made of complicated optical components to achieve sufficient detection resolution. Specifically, a prism coupled with an metal-coated glass is usually required to attain the SPR effect. The prism-glass complex is not only expensive, but often encounters the difficulty in optical coupling between the two components. These problems can be addressed by replacing the prism-glass complex with a thin GaN-based epi-wafer. Since the refractive index (RI) of GaN (n = 2.5) is much larger than that (n = 1.5) of the glass, the SPR effect can be easily achieved through the total internal reflection on the epi-surface, simplifying the optical design in the biosensor. The presented SPR structure comprises InGaN quantum wells coated with a thin Ag layer. Biomolecular interactions are sensed by the SPR effect induced at the GaN/Ag interface, where a minute change in RI can lead to measurable variation of the emission intensity from the quantum well. Preliminary results show that the sensitivity over 10000 %/RIU and the detection limit below 50 nM can be reached with the quantum-well-based biosensor. Details on device structure and performances will be presented.
9:00 PM - ED10.12.04
Electrokinetic-Manipulation Integrated Plasmonic-Photonic Hybrid Raman Nanosensors with Dual Enhanced Sensitivity
Chao Liu 1 , Zheng Wang 1 , Erwen Li 2 , Zexi Liang 1 , Swapnajit Chakravarty 3 , Xiaochuan Xu 3 , Alan X. Wang 2 , Ray T Chen 1 3 , Donglei (Emma) Fan 1 4
1 , The University of Texas at Austin, Austin, Texas, United States, 2 , Oregon State University, Corvallis, Oregon, United States, 3 , Omega Optics, Inc, Austin, Texas, United States, 4 , Novel Minds LLC, Austin, Texas, United States
Show AbstractTo detect biochemicals with ultra-high sensitivity, efficiency, reproducibility and specificity has been the Holy Grail in the development of nanosensors. In this work, we report an innovative type of photonic-plasmonic hybrid Raman nanosensors integrated with electrokinetic manipulation by rational design, which offers dual mechanisms that enhance the sensitivity for molecule detection directly in solution. For the first time, we integrate large arrays of synthesized plasmonic nanocapsules with densely surface distributed silver (Ag) nanoparticles (NPs) on lithographically patterned photonic crystals via electric-field assembling. With the patterned microelectrodes, the applied electric fields not only assemble the hybrid plasmonic nanocapsules on photonic crystals but also generate electrokinetic flows that focus analyte molecules to the Ag hot spots on the nanocapsules for Surface-enhanced Raman scattering (SERS) detection. The synergistic effects of plasmonic-photonic resonance and the electrokinetic molecular focusing can promote the SERS enhancement factor (EF) robustly to 5×109- 5×1010. Various molecules including SERS probing molecules, nucleobases, and unsafe food additives can be detected directly from suspension. The innovative mechanism, design, and fabrication reported in this work can inspire a new paradigm for achieving high-performance Raman nanosensors, which is pivotal for lab-on-chip disease diagnosis and environmental protection.
9:00 PM - ED10.12.05
Optical Contribution of Graphene in Enhanced Sensitivity of Graphene-Gold Coupled Surface Plasmon Resonance Sensing
Kyungwha Chung 1 , Kyungeun Lee 2 , Sang Ouk Kim 2 , Hyesung Park 3 , Dong Ha Kim 1
1 , Ewha Womans University, Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of), 3 , Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of)
Show AbstractSurface plasmons at metal/dielectric interface can resonate with the incident light depending on the incident angle, wavelength of the light or the refractive index (RI) of the medium. These characteristics have been utilized as a basis of surface plasmon resonance (SPR) sensors, providing label-free and real-time sensing format. However, the sensitivity of SPR sensors still needs to be improved to meet the requirements for the small molecule sensing. In order to enhance the performance, plasmonic nanomaterials have been introduced on SPR sensor chip.
Dirac fermions in graphene can behave like photons showing linear dispersion relation. In this regard, graphene can be utilized as an alternative plasmonic material to conventional metal nanostructure. Herein, we employed graphene from different preparation methods; graphene oxide (GO) using Hummer’s method, graphene from chemical vapor deposition (CVD) and N-doped reduced graphene oxide were incorporated on top of Au film of 50 nm thickness with the aim to increase electric field through coupling of graphene plasmons with propagating SPs from Au film which was located in Kretschmann configuration-based surface plasmon resonance spectroscopy. Thickness, reduction state and nitrogen doping state of graphene were systematically controlled and RI sensing was conducted. Au substrates with CVD graphene bilayers showed highest RI sensitivity (RIS) compared to bare Au film or Au film with other types of graphene and the figure of merit of Au/graphene substrates was not deteriorated due to the extremely thin graphene layer. Immuno-sensing was demonstrated with the mass sensitivity of 1430 pg/mm2, 3.3 times higher than that of bare Au film. Moreover, the optical contribution of graphene for the overall sensitivity enhancement mechanism could be confirmed by studying RIS. Therefore, graphene adlayers could amplify electric field and biomolecular adsorption which was experimentally proved by monitoring RIS and immunoassay.
9:00 PM - ED10.12
ED10.12.02 transferred ED10.9.04.5
Show Abstract
Symposium Organizers
Viktoriia Babicheva, Georgia State University
Alexandra Boltasseva, Purdue University
Harald Giessen, University of Stuttgart
Pavel Ginzburg, Tel Aviv University
Symposium Support
Neaspec GmbH
NKT Photonics Inc.
ED10.13: Novel Plasmonic Materials and Metamaterials
Session Chairs
Pavel Ginzburg
Arseniy Kuznetsov
Friday AM, April 21, 2017
PCC North, 100 Level, Room 131 B
9:15 AM - ED10.13.01
Palladium Germanides for Mid- and Long-Wave Infrared Plasmonics
Evan Smith 1 2 , William Streyer 3 , Nima Nader 1 4 , Shivashankar Vangala 5 1 , Richard Soref 6 , Daniel Wasserman 7 , Justin Cleary 1
1 Sensors Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, United States, 2 , KBRwyle Laboratories, Beavercreek, Ohio, United States, 3 Department of Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, Illinois, United States, 4 , Solid State Scientific Corporation, Nashua, New Hampshire, United States, 5 , Azimuth Corporation, Dayton, Ohio, United States, 6 The Engineering Program, University of Massachusetts, Boston, Massachusetts, United States, 7 Department of Electrical and Computer Engineering, University of Texas, Austin, Texas, United States
Show AbstractPalladium germanide thin films were investigated for infrared plasmonic applications. Palladium thin films were deposited onto amorphous germanium thin films and subsequently annealed at a range of temperatures. X-ray diffraction was used to identify stoichiometry, and SEM micrographs, along with Energy Dispersive Spectroscopy (EDS) was used to characterize composition and film quality. Resistivity was also measured for analysis. Complex permittivity spectra were measured from 0.3 to 15 µm using IR ellipsometry. From this, surface plasmon polariton (SPP) characteristics such as propagation length and mode confinement were calculated and used to determine appropriate spectral windows for plasmonic applications with respect to film characteristics. Films were evaluated for use with on-chip plasmonic components.
9:30 AM - *ED10.13.02
New Materials for Infrared and Active Plasmonics
Otto Muskens 1 , Christoph Riedel 1 , Kai Sun 1 , Cornelis de Groot 1
1 , University of Southampton, Southampton United Kingdom
Show AbstractPlasmonic antennas enable extremely compact optical devices that can operate in an extended spectral range and with active tunability of properties. In our work we combine materials research with advanced modelling and experiments to achieve new functionalities using plasmonic elements. Metal oxides such as indium-tin-oxide (ITO) and Al-doped ZnO (AZO) are Drude metals with negative permittivity in the infrared spectral range. We have developed processes for lift-off and etching of metal oxide antennas and have demonstrated plasmonic response at infrared wavelengths. The unique combination of dielectric response in the visible and plasmonic mid-IR response opens up new applications in optical sensing and spectroscopy, thermal management and metasurfaces. In particular, we present here new results exploiting metal oxide metasurfaces for passive thermal coatings in space technology. The feasibility of metasurfaces for optical solar reflectors is demonstrated experimentally using small-area prototypes. Metal oxides also provide a platform for electrical and all-optical tunability in near- and mid-IR. All-optical tuning makes use of synergy in the excitation and readout of the material optical nonlinearity through antenna-assisted local field concentration, possibly in combination with epsilon-near zero effects. By using a nanoscale electro-optical modelling approach we are also able to provide new designs for tunable antennas and metasurfaces exploiting electrically and optically controllable materials.
10:00 AM - ED10.13.03
High-Performance Doped Silver Films—Overcoming Fundamental Material Limits for Nanophotonic Applications
Cheng Zhang 1 2 , Nathaniel Kinsey 3 , Long Chen 1 , Chengang Ji 1 , Mingjie Xu 4 , Marcello Ferrera 6 , Xiaoqing Pan 5 7 , Vladimir Shalaev 8 , Alexandra Boltasseva 8 , Lingjie Guo 1
1 Department of Electrical Engineering and Computer Science, University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States, 2 Center for Nanoscale Science and Technology, National Institute of Standards and Technology , Gaithersburg, Maryland, United States, 3 Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia, United States, 4 Department of Materials Science and Engineering, University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States, 6 Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh United Kingdom, 5 Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California, United States, 7 Department of Physics and Astronomy, University of California, Irvine, Irvine, California, United States, 8 School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, United States
Show AbstractThe field of nanophotonics has ushered in a new paradigm for light manipulation by enabling deep sub-diffraction confinement assisted by metallic nanostructures. However, a key limitation which has stunted a full development of high-performance nanophotonic devices is the typical large losses associated with the constituent metals. Although silver has the highest figure of merit (i.e., ratio between real and imaginary part of its dielectric permittivity) for visible and near infrared plasmonic applications, its usage has been limited due to practical issues, such as difficulty in growing continuous thin films, instability when exposed to air or high temperatures, poor adhesion to substrates, and high surface roughness. In this work, we overcome these limitations by using a unique room-temperature process which incorporates a slight amount of aluminum during the silver deposition [1]. The result is a new kind of doped silver films with drastically improved quality that enables a continuous film formation down to 6 nm with sub-nanometer roughness, long-lasting chemical stability (even at high temperatures), as well as improved adhesion with substrates. This is all attained without degradation in the intrinsic material optical properties.
In order to demonstrate the flexibility and robustness of this material platform, we have investigated the applicability of doped Ag films in diverse nanophotonic systems including, hyperbolic metamaterials, transparent electrodes, and plasmonic interconnects [2]. First, we show that hyperbolic metamaterials consisting of ultra-thin doped Ag films can be attained having a homogeneous and low-loss response, and supporting a broad range of high-k modes as a direct consequence of the nanometric thickness and superior uniformity of the film. Secondly, transparent conductors based on doped Ag are demonstrated and proved to possess both a high and flat transmittance over the visible and near-IR range, giving an averaged transmittance of 92.4% from 400 nm to 1000 nm, and a sheet resistance as low as 20 Ohm/Sq. Finally, long-range surface plasmon polariton (LR-SPP) waveguides made of doped Ag are fabricated and characterized in the linear regime, which show propagation distances of few centimeters. Owing to its unprecedented quality, stability, smoothness, and simple room-temperature deposition, doped Ag provides the foundation for a new class of high-performance nanophotonic devices.
[1] An Ultrathin, Smooth, and Low-Loss Al-Doped Ag Film and Its Application as a Transparent Electrode in Organic Photovoltaics, Advanced Materials, 26, 32, 2014
[2] High Performance Nanophotonic Platform Utilizing Ultra-thin, Low-loss and Stable Aluminum-doped Silver Films, Under Review, 2016
10:15 AM - ED10.13.04
Doped Cadmium Oxide Thin Films Provide a Broadly Tunable, Low-Loss, and Scalable Plasmonic Material Platform
Evan Runnerstrom 1 , Kyle Kelley 1 , Edward Sachet 1 , Christopher Shelton 1 , Jon-Paul Maria 1
1 , North Carolina State University, Raleigh, North Carolina, United States
Show AbstractMaterials with tunable dielectric functions offer a platform to develop tunable plasmonic devices that manipulate light over broad spectral regions. Heavily doped semiconductors, particularly transparent conductive oxides (TCOs), are a particularly promising class of plasmonic materials with optical properties that can be tuned over much of the near- and mid-infrared (IR). This provides the ability to match plasmonic excitations to other optical transitions of interest in order to enable new modes of molecular sensing, hot carrier injection, etc. The efficacy of coupling plasmonic excitations to other optical processes is limited by optical losses within the plasmonic material itself; in this vein, TCOs are attractive because their interband transitions are too high in energy to interfere with their low energy plasmonic excitations, in contrast to more traditional plasmonic materials like gold. However, as semiconductors, TCOs are subject to ionized impurity scattering and suffer optical losses through electronic scattering. When large numbers of impurities are present, the electronic mobility and associated plasmon quality factors are greatly reduced. In 2015, our group showed that cadmium oxide (CdO), particularly when doped with dysprosium, is an excellent materials platform for low-loss, tunable mid-IR plasmonics, with very high free carrier mobility (up to ~500 cm2/Vs) and low damping enabled by suppressed ionized impurity scattering.
Here, we explore additional degrees of freedom for the CdO system, including thickness, substrate, and dopant choice, which afford additional tunability in carrier concentration, plasmonic properties, and epsilon-near-zero modes, while maintaining high carrier mobilities and low optical losses. For example, through the judicious use of dopants, including Ag+, Y3+, and In3+, we access two orders of magnitude in carrier concentration, with plasma frequencies spanning 12,500 cm-1 in the mid- and near-IR, combined with maximum electronic mobilities over 450 cm2/Vs. Furthermore, we utilize a relatively new physical vapor deposition technique, high power impulse magnetron sputtering (HiPIMS), which combines the advantages of magnetron sputtering (high deposition rates and scalability) with the advantages of molecular beam epitaxy (very smooth and dense films). In this talk, we will detail the properties of our plasmonic CdO thin films synthesized with various dopants, as well as the advantages of HiPIMS as a versatile and high quality fabrication technique for plasmonic oxide thin films. This will allow high quality TCOs to be integrated with semiconductor manufacturing processes, opening the door for advanced plasmonic devices, such as passive IR detectors, and for the advancement of advanced plasmonic experiments, such as hot carrier injection, plasmon-vibrational coupling, and more.
10:30 AM - *ED10.13.05
Plasmonic Metamaterials as a Self-Contained Platform for Optoelectronic Signal Processing
Wenshan Cai 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractMetallic nanostructures have offered not only the exciting opportunity to manipulate light waves in unconventional manners, but also the exciting potential to create customized nonlinear media with tailored high-order effects. Two particularly compelling directions of current interests are active plasmonics, where the optical properties can be purposely manipulated by external stimuli, and nonlinear plasmonics, which enable intensity-dependent frequency conversion of light. By exploring the interaction of these two directions, we leverage the electrical and optical functions simultaneously supported in nanostructured metals and demonstrate electrically-controlled nonlinear processes from plasmonic metamaterials. We show that a variety of nonlinear optical phenomena, including the wave mixing and the optical rectification, can be purposely modulated by applied voltage signals. In addition, electrically-induced and voltage-controlled nonlinear effects facilitate us to demonstrate the backward phase matching in a negative index material, a long standing prediction in nonlinear metamaterials. Other t to be covered in this talk include photon-drag effect in plasmonic metamaterials, ion-assisted nonlinear effects from plasmonic crystals in aqueous environments, and pixelated optoelectronic photosensors with tailored spectral and polarization responses. Our results reveal a grand opportunity to exploit plasmonic metamaterials as self-contained, dynamic platforms with intrinsically embedded electrical functions and optical nonlinearities for signal generation, light detection, information processing, and biochemical sensing.
11:30 AM - *ED10.13.06
Beyond Graphene Plasmonics
Tony Low 1
1 Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, United States
Show AbstractIn recent years, one of the most exciting development in nano-optics has been the observation of enhanced light-matter interactions through a plethora of dipole type polaritonic excitations in two-dimensional (2D) layered materials. In graphene, electrically tunable and highly confined plasmon-polaritons were observed, opening up opportunities for optoelectronics, bio-sensing and other mid-infrared applications. Going beyond graphene, I will survey the vast library of 2D materials hosts for various polaritonic modes, their optical spectral properties and figure-of-merits. I will end with two examples of new plasmonic materials; massive Dirac system such as transition metal dichalcogenides and anisotropic system such as black phosphorus. I will discuss how these systems can accommodate novel polaritons modes with chiral and hyperbolic properties, and how these novel properties can lead to new ways of manipulating light not possible with conventional materials, both in the near and far-field.
12:00 PM - *ED10.13.07
Nanoscopy of Black Phosphorus
Yohannes Abate 1
1 , Georgia State University, Atlanta, Georgia, United States
Show AbstractNanolayered and two-dimensional materials such as graphene, boron nitride, transition metal dichalcogenides, and black phosphorus have intriguing physical properties and bear promise of important applications. Of them, black phosphorus has unique electronic properties due to its anisotropic structure and highly tunable band gap both by number of monolayers and by surface doping. I will discuss our recent experimental investigation and theoretically interpretation of anisotropic near-field properties of a few-atomic-monolayer nanoflakes of black phosphorus. We have discovered near-field patterns of outside bright fringes and high surface polarizability of nanofilm black phosphorus consistent with its surface-metallic behavior at mid-infrared frequencies. The major impediment to research and prospective application of single/few-layer black phosphorus is its chemical degradation under ambient conditions. I will present our experimental quantification of geometric properties and theoretical modeling of the chemical degradation process of black phosphorus as well as investigation of the effectiveness of passivation coatings using infrared nanoscopy.
12:30 PM - ED10.13.08
Impedance Spectroscopy Characterization of Colloidal Indium Tin Oxide Films and Related Materials
Rosario Gerhardt 1 , Salil Joshi 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractImpedance and dielectric spectroscopy is used to describe a detailed study on the electrical properties of nanoparticulate films made from colloidal ITO nanoparticles. The highly crystalline ITO suspensions were spin coated onto glass substrates. After deposition, the films were treated with alternating oxygen and argon plasma treatments, followed by air annealing at various temperatures from 150°C to 750°C. Since the plasma treatments and annealing result in partial removal of the organic coating that prevented the nanoparticles from agglomerating, this provides an excellent system for demonstrating changes in the electrical response of films made from these highly conducting nanoparticles. The as deposited thin films were highly insulating but as the annealing temperature was increased, the impedance response became more representative of that of a conducting material. In spite of the high temperature and the plasma treatments used, the organic coatings prevented the films from achieving as high a conductivity as that of sputtered ITO films. Nevertheless, the frequency dependent impedance and dielectric spectra were rich in detail and showed the effects of the systematic removal of the organic coating. The impedance results can be explained by a nested equivalent circuit that contains a parallel RL circuit inside a parallel RC circuit. These results can be used to predict some plasmonic behavior in these materials.
12:45 PM - ED10.13.09
Extracting Dielectric Function of Plasmonic Metal Oxide Using Synchrotron-Based Infrared Nano-Spectroscopy (SINS) on Single Nanocrystal Scale
Ankit Agrawal 1 , Robert Johns 2 1 , Delia Milliron 1
1 , The University of Texas at Austin, Austin, Texas, United States, 2 , University of California, Berkeley, Berkeley, California, United States
Show AbstractDegenerately doped metal oxide has metal-like optical properties, and they offer an alternative to traditional metal. They exhibit similar and, in some ways, enhanced plasmonic responses in which the LSPR frequency is controlled through chemical composition as well as shape and size of the nanocrystal. Metal oxide nanocrystals can be colloidially synthesized and by controlling the nucleation and growth kinetic as well as ligand chemistry, it can be grown in different shapes and sizes. Colloidal synthesis, on the one hand, is cheap to scale up but it faces the challenge of output heterogeneity in shape, size and dopant concentration among the nanocrystals as well as dopant distribution inside the nanocrystal.
Deriving the dielectric property of such nano-system either using ellipsometry on nanocrystal film or fitting optical models to solution extinction spectra are usually not accurate. Both these methods don't take into account the synthetic heterogeneity and gives an average optical constant. In our previous work1,2, we have demonstrated that linewidth of ensemble spectra shows substantial ensemble broadening when compared to single nanocrystal spectra. To eliminate any artificial broadening effect, we have developed a method to extract the dielectric function of metal oxides such as Al:ZnO, Sn:In2O3 and Ce:In2O3. We employ finite element method to numerically fit the experimentally obtained SINS absorption spectra to tip-nanocrystal-substrate coupled system computed absorption spectra to extract the dielectric function of the nanocrystal. We use finite dipole method to estimate our initial guess, to ensure the fast convergence. The derived dielectric function is then used to quantify the heterogeneity within a colloidal system. These dielectric values are further used to predict the near field property of single and coupled metal oxide nanostructures.
References
(1) Johns, R. W.; Bechtel, H. A.; Runnerstrom, E. L.; Agrawal, A.; Lounis, S. D.; Milliron, D. J. Direct Observation of Narrow Mid-Infrared Plasmon Linewidths of Single Metal Oxide Nanocrystals. Nat. Commun. 2016, 7, 11583.
(2) Runnerstrom, E. L.; Bergerud, A.; Agrawal, A.; Johns, R. W.; Dahlman, C. J.; Singh, A.; Selbach, S. M.; Milliron, D. J. Defect Engineering in Plasmonic Metal Oxide Nanocrystals. Nano Lett. 2016, 16 (5), 3390–3398.
ED10.14: Novel Fabrication Techniques
Session Chairs
Friday PM, April 21, 2017
PCC North, 100 Level, Room 131 B
2:30 PM - ED10.14.01
Substrate Insensitive Plasmonic Titanium Nitride Film Deposited by Atomic Layer Deposition
Ing-Song Yu 2 , Hsyi-En Cheng 3 , Chun-Chieh Chang 4 , Yan-Wei Lin 1 , Hou-Tong Chen 4 , Yao-Chin Wang 5 , Zu-Po Yang 1
2 Department of Materials Science and Engineering, National Dong Hwa University, Hualien Taiwan, 3 Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan Taiwan, 4 Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 1 Institute of Photonic System, National Chiao Tung University, Tainan Taiwan, 5 Department of Biomedical Engineering, Hungkuang University, Taichung Taiwan
Show AbstractThe plasmonic nanostructures and metamaterials, which are typically made by gold (Au) and silver (Ag), have attracted great attention due to their promising properties and applications. However, there exist certain inherent issues for Au and Ag that prevent the proposed plasmonic nanostructures from achieving the expected performance. To address these issues, one of the strategies is to find alternative plasmonic materials. Among the proposed alternative plasmonic materials, titanium nitride (TiN) has a comparable loss to Au and other favorable properties compared to Au and Ag. Therefore, TiN is expected to have better performance for some applications than Au. Although different methods have been employed, sputtering is the most used means to deposit TiN films for the applications of plasmonics. However, it has been shown that the plasmonic properties of TiN films deposited by sputtering are fairly sensitive to the underlying substrates. Moreover, sputtering cannot perform the infiltration to have virtually conformal coating on 3D nanostructured templates. Therefore, it is desired to have a method to deposit TiN films with plasmonic properties that are weakly dependent on or even completely independent of the underlying substrates. It would be even more attractive if this deposition method can perform infiltration and conformal coating on 3D nanostructured templates for the fabrication of 3D TiN-based plasmonic nanostructures.
In this paper, we show that plasmonic properties of TiN films deposited by ALD have weak substrate dependence. This weak dependence suggests that, under a given deposition condition, the acquired plasmonic properties of TiN films deposited by ALD on one kind of substrate can be readily used to design and evaluate the optical performance of ALD-deposited TiN plasmonic nanostructures on any other substrate materials we studied here. Our results also show that the plasmonic properties of TiN films deposited by ALD on substrates with more nitrogen-terminated (N-terminated) surface slightly deviate from those of the films on substrates without N-terminated surface. In addition, we demonstrate that the plasmonic properties of TiN films on different substrates can be tailored simply by adjusting the deposition temperature and post-deposition annealing (PDA). Finally, a conformal coating of TiN film deposited by ALD on anodic alumina oxide (AAO) templates with a high aspect ratio was demonstrated, suggesting that ALD can be used to fabricate 3D TiN-based complex plasmonic structures.
This work is supported by Ministry of Science and Technology (contract no. MOST 105-2221-E-009-073, 105-2221-E-259-003, and MOST105-2221-E-218-001).
2:45 PM - ED10.14.02
Nonthermal Plasma-Synthesized Titanium Nitride Nanocrystals with Gold-Like Plasmonic Properties for Biological Applications
Katelyn Schramke 1 , Uwe Kortshagen 1
1 , University of Minnesota, Minneapolis, Minnesota, United States
Show AbstractGold nanomaterials of a certain shape and aspect ratio have a plasmonic resonance in the near-IR making them practical for biological applications including photothermal therapy treatments. Properties of metal nanomaterials are very dependent on their size and shape leading to a drastic change in properties with deformation. The inherent drawbacks of using gold materials are gold’s low deformation temperature as well as its high cost. Titanium nitride has similar desirable optical properties and is a thermally stable, biocompatible, and more cost-effective alternative to gold. Titanium nitride is a proven durable and biocompatible material as titanium nitride coatings have been used on components for joint replacements. In this work, we examine the optical properties of titanium nitride nanocrystals produced in the gas phase using a nonthermal plasma synthesis technique.
The titanium nitride nanocrystals are produced using tetrakis(dimethylamino)titanium (TDMAT) and ammonia (NH3) as the titanium and nitrogen precursors respectively, in an argon plasma. Titanium nitride nanocrystals exhibit a broad plasmon resonance with the peak near 850nm which is comparable to the absorbance of gold nanorods with an aspect ratio of 3.6. These nanocrystals have an average crystallite size of ~5nm as measured by x-ray diffraction and confirmed by transmission electron microscopy.
This work was supported by the Army Office of Research under MURI Grant W911NF-12-1-0407. Part of this work was carried out in the College of Science and Engineering Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the UMN MRSEC program and the College of Science and Engineering Minnesota Nanocenter, University of Minnesota, which receives partial support from NSF through the NNIN program.
3:00 PM - ED10.14.03
Efficient Combination of Interference and Plasmon Resonance Raman Amplification by Optimized Heterostructures for Optical Microscopy and Molecule Detection
Alicia de Andres 1 , Leopoldo Alvarez-Fraga 1 , Esteban Climent-Pascual 1 , Montserrat Aguilar-Pujol 1 , Rafael Ramirez-Jimenez 2 , Felix Jimenez-Villacorta 1 , Carlos Prieto 1
1 , ICMM- CSIC, Madrid Spain, 2 , Universidad Carlos III de Madrid, Leganés Spain
Show AbstractThe detection, identification and quantification of different types of molecules and the optical imaging of, for example, cellular processes are important challenges. The enhancement provided by electric field amplification due to localized plasmons of metallic nanoparticles, called SERS (surface enhanced Raman scattering) is the most efficient process however, the design of amplification platforms for the detection and imaging of extremely diluted and/or complex materials still requires further research and development to get cheap, reliable, reproducible and stable over time systems that can be easily reused several times.
Among the different mechanisms for Raman intensity amplification, the interference process has been scarcely investigated. Here we present how interference enhanced Raman scattering (IERS) in adequately designed heterostructures can provide amplification factors relevant both for detection and imaging. We report how interference enhancement substrates have to be designed to maximize their efficiency and how it is possible to combine SERS and IERS effects. The IERS platforms are demonstrated to improve significantly the quality of white light images of graphene and are foreseen to be adequate to reveal the morphology of ultrathin films and of biological material. We use a transfer matrix method to calculate the propagation of light through the heterostructure (reflecting layer/ dielectric layer/ graphene) for a large set of materials in order to obtain the general trends of Raman interference process and to optimize the effect in view of its application. Graphene is used here as the ideal material to reveal the amplification power of the tested platform and as the appropriate substrate for the deposition of organic molecules. We have designed and fabricated optimized heterostructures for IERS which combined with nanostructured silver films demonstrate the combined IERS + SERS amplification.
3:15 PM - ED10.14.04
Directed Nanopatterning of Self-Organized Bravais Lattices
Onur Tokel 1 , Ozgun Yavuz 1 , Ihor Pavlov 1 , Ghaith Makey 1 , Serim Ilday 1 , Omer Ilday 1
1 , Bilkent University, Ankara Turkey
Show AbstractIn spite of the recent successes of maskless optical nanopatterning methods, it remains extremely challenging to create any desired nanopattern on surfaces. Available optical nanofabrication techniques generally lack the long-range order required for large-area applications such as display technologies, and the high degree of periodicity demanded by photonics and photovoltaics applications. We recently demonstrated a novel approach to these problems with Nonlinear Laser Lithography (NLL)[1], where highly periodic nanopatterns are created over indefinitely large surfaces with the help of lasers. Here, we show that carefully preconditioned surfaces in the form of controlled defects can direct nanopatterns to all possible symmetries on surfaces. Further, we experimentally demonstrate that all Bravais lattices can be fabricated on titanium surfaces by using femtosecond lasers. Such an ability where directed nanopatterning is exploited to form and guide to predetermined symmetries is a new capability, not possible with other optical fabrication methods.
We show that the emergence of the motifs can be regulated and controlled by exploiting a self-consistency requirement between the field and nanopattern, while the polarization of the laser is used to prescribe the lattice symmetry, and the symmetry reinforces the translational invariance. In this approach, self-organized nanopatterns can be directed to desired patterns according to predictive symmetry rules, which allows for rapidly creating highly-controlled laser-induced patterns at the nanoscale without the use of any masks, enabling a new nanofabrication capability. We present a predictive model for the formation of such structures, and experimentally confirm the predictions of our model. The demonstrated directed nanopatterning approach will likely have applications in plasmonics, solar cells, photovoltaics, display technologies as well as in wettability and tribology.
[1] Oktem et. al., Nature Photonics 7, 897–901 (2013)
3:30 PM - ED10.14.05
Lithographically Patterned Plasmonic Au Nanotube Array for Solar Energy Harvesting
Hak-Jong Choi 1 , Daihong Huh 1 , Junho Jun 1 , Moon Sung Jin 1 , Yangdoo Kim 1 , Heon Lee 1
1 , Korea University, Seoul Korea (the Republic of)
Show AbstractCurrently, plasmonic nanostructures have been widely studied due to their unique properties, which can improve the performance of optoelectronic devices such as solar energy devices, optical sensors, and light emitting diodes.[1-2] Especially, various plasmonic nanostructures have been researched for their optical and electronic properties to overcome the limitations of current optoelectronic devices. In order to fabricate the various plasmonic nanostructures such as nanopillar, nanohole, nanocone, and nanowire, many lithographical techniques were already investigated and developed including electron beam lithography, photolithography, porous aluminum template, nanosphere lithography, nanoimprint lithography, and so on.[3] Recently, nanoring and nanotube like metallic structure have a lot of attention due to the unique electric and magnetic resonance and low optical loss.[4]
In this study, we report the characteristics of the free-standing metallic nanoring and nanotube array fabricated using template-assisted secondary sputtering process, which can control the height, pitch, shape, and diameter of Au nanoring and nanotube. Briefly, nanoimprinted polymer templates were used and targeted metal was deposited into the template. Then, Ar sputtering was conducted with adapted bias, which generate secondary sputtering process. Subsequently, templated was removed using chemical etchant. Finally, metallic nanoring or nanotube were completely fabricated on arbitray substrate.
The metallic nanoring or nanotube are analyzed using field-emission scanning electron microscopy (FE-SEM), UV-Vis spectrometer, and Ellipsometer. In addition, FDTD simulation results were compared with experimental data. Then, we confirmed multiple resonances were generated as Au nanotube due to magnetic resonance and Fabry-Perot resonance, which can enhance the light absorption.
References
V. E. Ferry, L. A. Sweatlock, D. Pacifici and H. A. Atwater, Nano Lett. 8, 4391-4397 (2008).
J. N. Anker, W. P. Hall, O. Lyandres, N. C. Shah, J. Zhao1 and R. P. V. Duyne, Nature Mater. 7, 442-453 (2008).
R. Walter, A. Tittl, A. Berrier, F. Sterl, T. Weiss and H. Giessen, Adv. Opt. Mater. 3, 398-403 (2015).
A. R. Halpern and R. M. Corn, ACS Nano 7, 1755-1762 (2013).
3:45 PM - ED10.14.06
Nanoimprinted Self-Folding Mid-IR Tunable Metasurfaces
Vivek Nagal 2 , Tengfei Li 1 , Jacob Khurgin 1 , David Gracias 2
2 Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States, 1 Department of Electrical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
Show AbstractA significant challenge in plasmonics and metamaterial science and engineering is the fabrication of reproducible patterned surfaces over large areas in a cost-effective manner. In this work, we demonstrate the use of nanoimprint lithography (NIL) for fabrication of gold metasurfaces with well defined spectral responses in the mid-IR region. Experimental spectra are in good agreement with FDTD calculations. Further, by utilizing a residual stressed thin film layer, we achieved self-folding, resulting in significant changes in the IR response of the curved nanostructured metasurfaces. Overall, our approach indicates how NIL and thin film strain driven assembly can be used to create reproducible, and tunable metasurfaces in the mid-IR region.
ED10.15: Self-Assembly Methods for Nanostructures and Metamaterials
Session Chairs
Pavel Ginzburg
Cheng Zhang
Friday PM, April 21, 2017
PCC North, 100 Level, Room 131 B
4:30 PM - ED10.15.01
Measuring of the Energy Transfer Efficiency between Plasmon Nanoparticles and Quantum Dots Using Sample-Transmitted Excitation Photoluminescence (STEP)
Pavel Moroz 1 , Mikhail Zamkov 1
1 , Bowling Green State University, Bowling Green, Ohio, United States
Show AbstractMetal plasmonic nanoparticles represent unique class of the materials which can efficiently concentrate light in photovoltaic devices. Such energy transfer could potentially improve device absorption characteristics if the plasmon energy is directly converted to excitons in the semiconductor acceptor. Here, we report spectroscopic measurements of the energy transfer efficiency between metal and semiconductor domains in a hybrid metal-semiconductor nanocrystal film. Using a sample of colloidal nanoparticles as an optical filter which removes the portion of the excitation light, we were able to measure the energy transfer rate between Au and PbS nanocrystals.
5:00 PM - ED10.15.03
Engineering Disordered Metamaterials for Broadband High Optical Absorption
Sheldon Hewlett 1 , Adam Mock 1
1 , Central Michigan University, Mt Pleasant, Michigan, United States
Show AbstractDisordered metamaterials are engineered materials with optical properties which are distinct from those of the constituent materials. These constituent materials often consist of randomly distributed metal nanoparticles in a dielectric matrix. While disordered metamaterials are promising for use in light harvesting applications, few studies have investigated the role of nanoparticle size and spatial distribution in enhancing optical absorption. In the presented research, disordered metamaterials made from gold nanoparticles in solution were fabricated using a simple drop cast process. After drying the resulting metamaterials are a dense, random agglomeration of nanoparticles which we call dense nanoparticle stacks (DNpS). This simple and cheap fabrication process is scalable which makes it suitable for large-scale industrial deployment. However, it allows for relatively little control over the spatial distribution of the constituent particles. On the other hand, in this presentation, we show how spatial control of nanoparticle size and position in the vertical direction can be used to increase optical absorption. Our DNpSs were engineered to obtain maximum absorption by utilizing a trilayer geometry with each layer composed of nanoparticles of a different size. This imposed vertical size grading showed higher absorption over samples whose nanoparticles were randomly distributed either during deposition or before deposition. Overall, DNpS exhibit optical absorptions as high as 95% with very low reflectivity, making them ideal candidates for light harvesting applications. In addition, these structures exhibit broadband absorption in the visible range while being inexpensive to fabricate. The underlying electromagnetic interactions in DNpS were subsequently modeled using finite-difference time-domain (FDTD) modeling, with good agreement between the experimental and modeling results.
5:15 PM - ED10.15.04
Block-Copolymer Based Self-Assembled Hyperbolic Metamaterials in the Visible Range
Xuan Wang 1 , Kevin Ehrhardt 1 , Morten Kildemo 2 , Alexandre Baron 1 , Ashod Aradian 1 , Virginie Ponsinet 1
1 , Centre de Recherche Paul Pascal-Université de Bordeaux, PESSAC France, 2 , NTNU, Trondheim Norway
Show AbstractNovel optical properties in the visible range are foreseen when organizing nanoresonators, which can be performed by the self-assembly of plasmonic nanoparticles prepared by wet chemistry. In this project, we prepare and study thin films of nanocomposites of polymers and gold nanoparticles. Our goal is to relate the structure of the composites, and in particular the nature, density and spatial organization of the nanoparticles, with their optical index. The anisotropic nanocomposites are produced by the assembly of gold nanoparticles (NPs) templated by ordered matrices of diblock copolymers. In particular, lamellar nanocomposite films are obtained by self-assembly of poly(styrene)-b-poly(2-vinyl pyridine) (PS-P2VP) copolymers, followed by gold NPs selective incorporation, and studied by X-ray scattering and scanning electron microscopy (SEM). They consist in periodic lamellar stacks of alternating layers of pure polymer (dielectric) and of composite of polymer loaded with a high density of 9 nm-diameter gold nanoparticles, with a total thickness between 200 and 600 nm and the subwavelength characteristic size do chosen between 20 and 70 nm. The amount of gold in the composite layers can be varied up to typically 40 volume%.
The optical properties of the nanocomposite films are determined by variable angle spectroscopic ellipsometry and analyzed by appropriately developed effective medium models. As can be seen on an example shown in the Figure, the films are structurally uniaxial and homogeneous, and we can define their dielectric permittivity tensor with the ordinary (parallel to the substrate) and extraordinary (normal to the substrate) components. The analysis of the lamellar structures allows the extraction of the components εo and εe, both presenting a resonance close to 2.3 eV, with a significantly stronger amplitude for εo. When the gold load is high enough and the couplings between particles are strong enough, the values of εo become negative close to the resonance, and the material reaches the so-called hyperbolic regime, which constitutes a step towards applications in hyper-resolution imaging.
5:30 PM - ED10.15.05
Dynamic Plasmonic Metamaterials with Broken Symmetry Created via Directed Self-Assembly
David Litt 1 2 , Matthew Jones 1 2 , Mario Hentschel 4 , A. Paul Alivisatos 1 2 3
1 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 Department of Chemistry, University of California, Berkeley, Berkeley, California, United States, 4 4th Physics Institute, University of Stuttgart, Stuttgart Germany, 3 Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States
Show AbstractMetamaterials are low symmetry architectures that interact with light in novel ways, and have opened a window into studying light-matter interactions. However, they are commonly fabricated via lithographic methods, are usually static structures, and therefore cannot react to external stimuli. Creating a dynamic metamaterial that responds to its environment would advance many fields that rely on light-matter interactions. Previously, plasmonic structures that are self-assembled with biological linkers such as DNA have been shown to dynamically interact with small molecules and have been used as detection platforms. However, unlike most metamaterials, they are highly symmetric and therefore have a relatively small plasmon shift upon binding target molecules. Here we show that by combining lithographic techniques with DNA-based self-assembly methods, dynamic plasmonic metamaterials can be generated with low-symmetry geometries that dramatically change their spectra upon motion of their constituent parts. The dynamic metamaterial we have synthesized exhibits electromagnetically induced transparency (EIT), an optical property which is highly-dependent on the arrangement and movement of its plasmonic nanoparticle components. The foundation of the structure is fabricated with lithographic techniques, and then through multi-layer exposure, a portion of the architecture is selectively functionalized with DNA. The remainder of the structure is assembled by hybridizing a DNA-functionalized gold nanorod to the exposed complementary DNA patch. These flexible DNA linkers impart the dynamic sensitivity of the platform. Correlative scanning electron microscopy measurements, scattering dark field microscopy, and computational simulations are performed on single assemblies to determine the relationship between the structures and their scattering spectra in response to a variety of external stimuli. The strength of the EIT effect in these assemblies can be tuned by precisely controlling the positioning of the plasmonic nanoparticles in these structures. By manipulating the environment of the DNA in a flow cell set-up, the coupling of the components in the system can be dynamically tuned to further control the EIT property. For example, changing the ionic environment or dehydrating the sample will change the conformation of the DNA linkers and therefore the distance between the nanoparticles. Dark field spectra of individual assemblies show peak shifts of up to many tens of nanometers upon DNA perturbations. This dynamic metamaterial represents a stepping stone towards more sensitive plasmonic detection platforms and next-generation dynamic metamaterials.
5:45 PM - ED10.15.06
Continuous Flow Colloidal Synthesis and Stabilization of Gold-Polystyrene Patchy Particles and their Thin Film Assembly into Layers with Particle-Anisotropy Dependent Optical Properties
Thomas Meincke 1 4 , Marcel Rey 1 4 , Ines Spies 1 4 , Johannes Walter 1 4 , Satoshi Watanabe 5 , Nicolas Vogel 1 2 3 , Robin Klupp Taylor 1 2 3
1 Institute of Particle Technology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 4 Graduate School "Advanced Materials and Processes", Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 5 Department of Chemical Engineering, Kyoto University, Kyoto Japan, 2 Interdisciplinary Center for Functional Particle Systems, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 3 Cluster of Excellence "Engineering of Advanced Materials", Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany
Show AbstractPatchy particles comprising plasmon resonant patches coated onto dielectric core particles represent a highly promising class of novel functional material. Besides the anisotropic optical properties, which can be tuned by the patch morphology, the directional interactions between patches in a dispersion of such particles may be used to assemble novel film structures with useful sensing, optical filtering or pigmentary properties. There remains however a lack of simple approaches for the synthesis of such particles and almost no studies of their deposition using standard thin-film techniques.
In this contribution we describe the simple and scalable synthesis, post-treatment and substrate deposition of plasmon resonant patchy particles. Nanometric thin gold patches are coated onto polystyrene core particles having diameters as small as 80 nm using a novel template-free and seed-free liquid phase method. Here we rely on the enrichment of the metal precursor and reducing agent at the core particle surface and subsequent heterogeneous nucleation and surface diffusion driven conformal growth of the metal. To ensure a narrow distribution of metal patch numbers and coverages, we replace the initially-developed batch process with a setup based on a continuous flow static mixer. Going from poor to good mixing in this setup we show, using spectroscopic analytical ultracentrifugation, how the distribution of patch dimensions and hence the plasmon resonant properties of the particles can be optimized. We go on to demonstrate that with appropriate core particle and reactant concentrations, the resonance wavelength of the resulting particles can be tuned. Besides achieving a range of patches partially covering the core we show that it is possible to produce coated particles having optical properties similar to those predicted by multishell Lorenz-Mie simulations for complete gold nanoshells with thicknesses as low as 10 nm. We thus offer a considerably simpler route to plasmon resonant nanoshells compared to the well-known seeded growth approach.
We go on to demonstrate how the initially colloidal unstable gold-PS patchy particles can be stabilized and we show how the resulting dispersion can be deposited, by dip-coating or following assembly at the liquid-air interface, onto a substrate. We explore the tuning of particle-particle interactions from non-directional to strongly directional via in situ patch functionalization during patchy particle deposition. In doing so we attempt to reconfigure the morphology of the resulting film during its growth. The resulting films are evaluated by electron and optical microscopy, UV/VIS/NIR and Raman spectroscopy and we deduce the contribution of the patch morphology and patch-patch plasmon coupling on the measured properties.