Nader Engheta University of Pennsylvania
Joshua Le-Wei Li National University of Singapore
Ruth Pachter Air Force Research Laboratory
Minas Tanielian Boeing Research and Technology
Tuesday AM, December 01, 2009
Room 104 (Hynes)
9:30 AM - **EE1.1
Photonic Metamaterials: Recent Progress.
Martin Wegener 1 Show Abstract
1 Institut fur Angewandte Physik, Universitaet Karlsruhe (TH), Karlsruhe Germany
We review recent progress regarding metamaterials operating at optical frequencies. Emphasis is put on three-dimensional chiral structures made via direct laser writing and gold electroplating, on enhanced nonlinear optical properties, and on interaction effects among magnetic split-ring resonators.
10:00 AM - **EE1.2
Xiang Zhang 1 Show Abstract
1 , University of California at Berkeley, Berkeley , California, United States
Metamaterials are artificially designed subwavelength composites that possess extraordinary properties not existing in naturally occurring materials. In particular, they can alter the propagation of electromagnetic waves resulting in negative refraction, subwavelength focusing and even in cloaking of macroscopic objects. Such unusual properties can be obtained by a careful design of dielectric or metal-dielectric composites on a deep sub-wavelength scale. The metamaterials may have profound impact in wide range of applications such as nano-scale imaging, nanolithography, and integrated nano photonics. I will discuss a few recent experiments demonstrating intriguing phenomena associated with Metamaterials. These include subdiffraction limit imaging and focusing, low-loss and broad-band negative-refraction of visible light, negative-index metamaterials and the first cloak operating at optical frequencies; an all-dielectric “carpet cloak” with broad-band and low-loss performance. I will also present our recent demonstration of sub-wavelength plasmonic laser.
10:30 AM - EE1.3
Negative Refractive Index at Visible Frequencies in Metamaterials based on Coupled Coaxial Resonators.
Rene de Waele 1 2 , Stanley Burgos 2 , Harry Atwater 2 , Albert Polman 1 Show Abstract
1 Photonic Materials, FOM Amolf, Amsterdam, Noord-Holland, Netherlands, 2 Applied Physics, California Institute of Technology, Pasadena, California, United States
Metamaterials are artificial materials with properties derived from sub-wavelength structuring rather than atomic composition. By controlling the nanoscopic current flow in the structuring elements metamaterials have been achieved that mimic magnetism at optical frequencies. This has opened the way to metamaterials with a negative index of refraction, characterized by simultaneously negative permittivity and permeability. So far, operation of optical negative-index functional metamaterials with considerable figure-of-merit (FOM) has been limited to the near-infrared. We propose a new metamaterial design that enables a negative index of refraction with large figure-of-merit (FOM) in the blue spectral region over a broad angular range. The metamaterial is built up from coupled coaxial waveguides with Ag cores and GaP channels embedded in Ag.
The refractive index and FOM of the metamaterial are largely determined by the dispersion relation of the constituent waveguide elements, and are thus strongly tunable via changes of the coaxial geometry or composition. Based on analytical calculations of the optical dispersion in single waveguides we establish that certain coax geometries can exhibit a negative index of refraction with large FOM at optical frequencies above the surface plasmon resonance. In case of waveguides with 75-nm diameter Ag core and 25-wide GaP we find a refractive index n = -1.8 at a wavelength of ~480 nm with FOM>8.
Using finite-difference time-domain simulations we study the properties of a metamaterial consisting of a triangular lattice of coupled Ag/GaP/Ag coaxial waveguides with these dimensions, at a pitch of 165 nm. Our simulations show that light inside the metamaterial exhibits anti-parallel phase and energy velocity and refracts at negative angles. By averaging the Poynting vector over a unit cell of the material and using Snell’s law we find that the refractive index of the material equals -2, i.e. very close to the mode index of a single waveguide, and also in agreement with the observed wavelength inside the metamaterial. Based on the exponential energy decay in the layer and the refractive index value we obtain a FOM larger than 8. Both the material index and FOM are nearly independent of the angle-of-incidence over an angular range ±50 degrees and independent of the polarization.
To further corroborate these results, we performed simulations to obtain the complex reflection and transmission coefficients for a thin slab of metamaterial. In agreement with the index derived from Poynting vector calculations, we find a refractive index of -2, and estimate a FOM of nearly 8, at an incoupling efficiency of 25%.
10:45 AM - EE1.4
General Properties of Dielectric Metamaterial Subunits.
Jon Schuller 1 , Mark Brongersma 1 Show Abstract
1 , Stanford University, Stanford, California, United States
In metamaterials, periodic or random ensembles of subwavelength structures can be used to form artificial materials that respond to light in a unique and carefully designed fashion. In most metamaterials the constituent subunits are metallic structures. Recently however, researchers have demonstrated the capability to fabricate metamaterials based on spherical or cylindrical dielectric particles. Such dielectric-based metamaterials can be constructed from dissipationless and highly symmetric subunits, and thus ultimately may lead to lossless and isotropic metamaterials.Here, using analytical Mie theory we investigate the resonances of spherical and cylindrical dielectric particles and derive a number of generalized results. Specifically, we prove that the peak scattering cross-section of radiation-limited (dissipationless) systems depends only on the resonance frequency and thus is independent of size and refractive index. By comparing with resonance fluorescence experiments and theory, we demonstrate that this size-independence is valid even for atomic systems and is a signature of the illuminating geometry. Although the peak response depends only on frequency, we show that the resonance bandwidth is strongly size-dependent. We apply the Chu limit from antenna theory to derive geometric scaling laws which relate resonance bandwidth to particle size. The derived scaling laws demonstrate a fundamental tradeoff relevant to lossless metamaterial design--the smaller the constituent subunits the narrower-band the frequency response. We then describe a cylindrical mode which is unique in its ability to support extremely large bandwidths even when the particle size is deeply subwavelength. Finally, we theoretically investigate the response of metamaterials comprising particle arrays and compare with the derived results for single Mie scatterers.
11:30 AM - **EE1.5
Microwave and Optical Cloaking using Transmission-Line and Parallel-Plate Artificial Materials.
Sergei Tretyakov 1 , Pekka Alitalo 1 , Olli Luukkonen 1 , Constantin Simovski 1 Show Abstract
1 , Helsinki University of Technology, Espoo Finland
In this review presentation we will discuss the use of artificial electromagnetic materials (metamaterials) for broadband cloaking applications. We will review our recent results on the cloaking technique, which employs networks of transmission lines. We will show how a mesh of metal conductors can transport electromagnetic waves leaving some space free of the fields (that is, cloaked). Broadband antenna applications in reducing coupling between antennas and nearly positioned large metal structures and in removing reflections from microwave lenses will be demonstrated. Furthermore, we will present a meta-structure composed of a set of thin metal sheets, which can cloak electrically long objects from electromagnetic radiation polarized along the object axis. In contrast to the known approaches based on transformational optics, this design does not need any exotic materials (only metal sheets). With an appropriate choice of the structure dimensions, this cloak can operate at frequencies from microwaves tothe visible light. Experimental results of a microwave design confirms cloaking in a wide frequency range.
12:00 PM - EE1.6
Transformation Optics by using Indefinite Metamaterial.
Yongjian Huang 1 , Bernard Didier Frederic Casse 1 , Srinivas Sridhar 1 Show Abstract
1 Physics, Northeastern University, Boston, Massachusetts, United States
Transformation optics can deals with the transformation of the Maxwell equations due to a transformation of the coordinate system. To implement the material designs requires precise control over spatial variance and anisotropy. Indefinite metamaterial which have extremely anisotropic properties can be used to design special optical device. Here we present an anisotropic lens and its lens equation. The ray-diagram is also given to show the advantage of such lens.
12:15 PM - EE1.7
Near-Field Optical Microspectroscopy on Oxide-Based Superlenses.
Susanne Kehr 1 , Lane Martin 1 , Yongmin Liu 2 , Asif Khan 3 , Martin Gajek 1 , Pu Yu 1 , Marc Wenzel 4 , Hans-Georg von Ribbeck 4 5 , Rainer Jacob 5 , Stephan Winnerl 5 , Manfred Helm 5 , Xiang Zhang 2 , Lukas Eng 4 , Ramamoorthy Ramesh 1 Show Abstract
1 Department of Physics, University of California Berkeley, Berkeley, California, United States, 2 Department of Mechanical Engineering, University of California Berkeley, Berkeley, California, United States, 3 Department of Electrical Engineering and Computer Sciences, UC Berkeley, Berkeley, California, United States, 4 Institute of Applied Physics, Technische Universität Dresden, Dresden Germany, 5 Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, Dresden Germany
Metamaterials, i.e. artificial materials with unique material properties, exhibit many intriguing optical phenomena and potential applications, such as negative refraction , cloaking , perfect lens  etc.. In order to realize a perfect lens that creates a perfect image with a resolution beyond the diffraction limit, the refractive index of a metamaterial should be negative, that is, the permittivity as well as the permeability need to be simultaneously negative . However, similar effects can be found in materials with a negative permittivity only, as e.g. in a superlens, which results in a perfect image for transverse-magnetic (TM) waves only [3,4,5]. In this abstract, we report the first study of oxide-based superlenses based on the dielectric oxides BiFeO3, SrTiO3 and PbZr0.2Ti0.8O3 (PZT), which show a negative permittivity in the infrared wavelength range close to phonon resonances with small absorption of light compared to metals. The samples consist of three layers, which are grown epitaxially by means of pulsed laser deposition.Near-field scanning optical microscopy (NSOM) allows for the examination of evanescent waves close to a sample surface. With this method an optical resolution well beyond the diffraction limit can be reached. As the superlens transforms the evanescent waves of an object into the image plane, NSOM can be used to image these evanescent fields . In this work, we combine such a scattering-type NSOM with the free-electron laser at the Forschungszentrum Dresden-Rossendorf, which is precisely tunable in the wavelength range from 4 to 200 µm [6, 7]. This allows us to excite the oxide-based superlenses at the appropriate wavelengths as well as to study their spectral response. We present NSOM measurements of two different sample systems consisting of the three layers BiFeO3-SrTiO3-BiFeO3 and PZT-SrTiO3-PZT, respectively. We study the lateral distribution of evanescent waves in the image plane as well as their dependence on the wavelength and on the probe-sample distance. In addition we examine the response of superlenses with a missing top layer on the image side, which allows us to study the interface phonon polariton more closely. Comparisons with numerical simulations show a good consistency with these experimental findings.  V.G. Veselago, Soviet Physics Uspekhi 10 (4), 509 (1968). J. B. Pendry, D. Schurig, and D. R. Smith, Science 312, 1780 (2006). J.B. Pendry, PRL 85 (18), 3966 (2000). N. Fang et al., Science 308, 534 (2005). T. Taubner et al., Science 313, 1595 (2006). S.C. Kehr et al., PRL 100, 256403 (2008). S.C. Schneider et al., APL 90, 143101 (2007).
12:30 PM - **EE1.8
Dielectric Building Blocks for Metamaterials and Active Nanophotonics.
Mark Brongersma 1 Show Abstract
1 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States
Metamaterials and nanophotonics devices are most commonly constructed from metallic nanostructures. However, recent research has begun to exploit the scattering resonances of high-permittivity particles to realize similar optical functionalities. In this talk, we experimentally and theoretically characterize the resonant modes of subwavelength, rod-shaped dielectric objects and demonstrate their use in negative index metamaterials, novel infrared light emitters, and photodetectors.
Tuesday PM, December 01, 2009
Room 104 (Hynes)
2:30 PM - **EE2.1
Toward Practical Metamaterials in the Thermal Infrared.
Michael Sinclair 1 Show Abstract
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Metamaterials form a new class of artificial electromagnetic materials that provides the device designer with the ability to manipulate the flow of electromagnetic energy in ways that are not achievable with naturally occurring materials. However, progress toward practical implementation of metamaterials, particularly at infrared and visible frequencies, has been hampered by a combination of absorptive losses; the narrow band nature of the resonant metamaterial response; and the difficulty in fabricating fully 3-dimensional structures. We will describe the progress of a recently initiated program at Sandia National Laboratories directed toward the development of practical 3D metamaterials operating in the thermal infrared. A prime objective of the program is to reduce the reliance on metallic structures so as to minimize the ohmic losses that severely degrade the performance of current metal-based infrared metamaterials. We will describe the design, fabrication, and performance of a negative index RF metamaterial based upon dielectric spheres, and we will describe our efforts to extend this approach to infrared wavelengths. We will also describe our progress toward the development of infrared metamaterials based upon polaritonic dielectrics such as Silicon Carbide. Another important issue that we will discuss is the development of low loss, low permittivity, infrared matrix materials and substrates that will be required in the fabrication of 3D infrared metamaterials. We will describe our utilization of the high performance computing resources at Sandia National Laboratories to perform direct numerical simulations of finite, aperiodic metamaterial devices. Such simulations allow us to investigate the impact of boundary layer effects and scattering from coarse gradients on metamaterial device performance. Finally, we will describe several new approaches to metamaterial characterization that we have implemented which enable unambiguous determination of the amplitude and absolute phase of transmitted and reflected waves. Such a capability allows for the retrieval of effective material parameters from measurements rather than simulations. This work is supported by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.
3:00 PM - **EE2.2
Compact Waveguide Band-Pass and Band-Stop Filters Using Negative Index Material (NIM) Concepts.
T. Lam 1 , R. Greegor 1 , Claudio Parazzoli 1 , M. Tanielian 1 Show Abstract
1 , The Boeing Company, Seattle, Washington, United States
Inspired by frequency selective properties of NIM unit cells, split ring resonators (SRR) and complementary SRR’s are adapted for use in the design of filters in waveguides. Initially conceived to reduce co-site interference between adjacent transmit and receive phased array antennas (PAA) operating in the 15GHz range, they could be used in any waveguide applications requiring frequency selectivity. Design simulations and experimental results are presented for complimentary SRR structures for band pass filters as well as conventional SRR structures for band stop filters having unit cell sizes in the λ/d~3 range. The fabrication techniques use standard lithographic procedures for ½ ounce copper on Rexolite substrates.
3:45 PM - EE2.3
Circuit Analog RF-Visual Antireflection Coatings.
Nicci Dehuff-Abueg 1 , Thomas Delfeld 1 Show Abstract
1 , Boeing, Seattle, Washington, United States
The Boeing Company has modeled, fabricated and measured antireflective (AR) coatings that perform at grazing angles (80°), in the long wave infrared (LWIR). The coatings were designed to perform best at 10 microns, and moderately well over the 8 to 12 micron region. The modeling was based on a circuit analog sheet (capacitive) that is buried within a dielectric, to produce a reflection that adds out of phase with the face sheet reflection. The capacitive sheet is formed from metallic patches and is designed to have a very high impedance for the TM component of the polarization. If desired, in order to improve the TM transmission as well as the TE, two layers can be used at different depths. This dual-layer approach has also been modeled, fabricated and measured. Also, explored in this paper are the impacts of a design that works well azimuthally at grazing angles. Until recently, the above solution would only be limited to RF frequencies, but with advances in fabrication it has become possible to fabricate very small nano structures that operate in LWIR using traditional thin-film vacuum deposition techniques. It is envisioned that eventually such a concept could be used in the visual regime via self assembly.
4:00 PM - EE2.4
Symmetry Breaking and Coupling Effects in Near-infrared Metamaterials.
Koray Aydin 1 , Imogen Pryce 1 , Harry Atwater 1 Show Abstract
1 Thomas J. Watson Lab. of Applied Physics, California Institute of Technology, Pasadena, California, United States
Metamaterials with novel electromagnetic properties such as artificial magnetism, negative refraction, cloaking and superlensing have received a burgeoning amount of interest in recent years. Split-ring resonators (SRR) are commonly used in designing metamaterials over a broad range of frequencies from microwave to near infrared. At microwave frequencies, desired electromagnetic responses could be achieved with a double SRR design; however, available electromagnetic responses at near-infrared wavelengths are limited due to the size effects and fabrication challenges of SRRs. Here, we propose an alternative metamaterial design utilizing coupled asymmetric SRRs at near-IR wavelengths. We introduce coupling as an additional design parameter which allows us to further engineer metamaterial resonances and achieve superior device performances. We will present our experimental and simulation results on the effect of coupling in several asymmetric split-ring resonator arrays. 100 x 100 μm Au SRR arrays (with an in-plane periodicity of 750 x 975 nm and sizes of 360 x 450 nm) on indium tin oxide (ITO) coated glass substrates are fabricated using conventional e-beam lithography. Transmission spectra of SRR arrays are measured using FTIR spectroscopy between 1.4 and 3.0 µm. FDTD simulations are made to calculate the transmission spectra using. Measured complex refractive indices of Au and ITO are used in the simulations which provided a very good agreement between the simulations and experiments. The magnetic and electric field intensities inside the SRR structure at different resonance wavelengths are calculated. Asymmetric coupled SRR design is advantageous in achieving narrower spectral linewidths at the resonance frequency. Frequency selective metamaterial surfaces could be used as modulators, filters and sensors at IR wavelengths. For practical applications, it is desirable to tune the resonant wavelength by a line-width of the resonance peak (FWHM). A narrower resonant peak will increase the tuning figure of merit (FOM), the ratio of the tuning range to the FWHM of the resonant peak. Simply, by breaking the structural symmetry of metamaterials we have experimentally and theoretically shown that narrower metamaterial resonances could be obtained. Different coupling schemes resulted in different peak positions in the reflection spectra. We observe that the resonant peak shift depends on the coupling strength of resonator elements. Finally, we employed SRRs with broken symmetries in active metamaterials based on vanadium-oxide (VO2) phase transition. We have observed that the FWHM of the reflection peak at the resonance wavelengths of asymmetrically coupled SRRs is 0.5 µm, whereas U-shaped SRRs have FWHM of 1.25 µm. We tested our proposed alternative design in metamaterial based active devices which considerably improved the device performance. Alternative active metamaterial design ideas inspired by the asymmetrically coupled SRRs will be provided.
4:15 PM - EE2.5
Lattice Density Effect on the Negative Refractive Index of a Uniaxial Metamaterial.
Enrico Prati 1 , Claudio Amabile 1 Show Abstract
1 Laboratorio Nazionale MDM, CNR , Agrate Brianza Italy
Electromagnetic metamaterials are the key elements of interesting and potentially groundbreaking applications in several fields of electromagnetism, from radiofrequencies to optics, but systematic and accurate experimental characterization of bulk media still lacks. In some relevant applications of metamaterials, such as evanescent mode lensing first conjectured by J. Pendry, a precise control of the negative refractive index value is required for fine tuning around n = -1. It is therefore necessary an accurate knowledge of how the effective constants depend on both the constructing parameters and the frequency of the electromagnetic field, in view of broad band applications. According to classical dielectrics theory, the effective constants depend on the features of both the elementary cell (the single resonator) and the lattice spacing. Few is published upon the lattice dependence. The purpose of this work is to get a better insight onto the dependence upon the lattice spacing of microwave frequency metamaterials based on a hollow waveguide filled with split ring resonators (SRRs), recognized to constitute an uniaxial metamaterial. Analytical expressions for the permeability of SSRs were worked out by different groups (Pendry,Marques,Gorkunov) but inhomogeneous results were found. In particular the dependence upon the density of SRR has different functional forms from work to work. The dependence of the electromagnetic constants upon the resonators density was demonstrated in some experimental studies (Varadan,Powell} but the conclusions are in disagreement about which feature of the effective medium depends upon the single resonator and which one upon their arrangement. Anyway, the clarification of the relation between the density and the electromagnetic constants was not the main objective of those experiments. On the contrary, we performed an experiment specifically devoted to the study of the effects of lattice density on the effective refractive index of SRR based metamaterials. We used SRR as basic elements of our metamaterial due to the abundance of literature and to their importance for applications. We studied their effective permeability and consequently their (negative) refractive index near the resonance around n = -1 because it is the frequency regime of greatest practical interest. Moreover, important deviations from usual behaviours may arise in such range. We show that the resonance frequency of the effective medium depends only on the single resonator properties, whereas its bandwidth and dissipated power depend on the density. We will also work out a threshold density below which the negative permeability behaviour disappears. Finally we provide the dependence upon density of the refractive index of the effective medium, as a function of the microwave frequency.
4:30 PM - EE2.6
Realization of Electrically Small Patch Antennas Loaded with Metamaterials.
Diana Strickland 1 , Jeremy Pruitt 1 , Jerome Helffrich 1 , Brandon Nance 1 , Emilio Martinez 1 , A. Leigh Griffith 1 Show Abstract
1 , Southwest Research Institute, San Antonio, Texas, United States
We have built and tested electrically small (~λ/10) resonant patch antennas as proposed in recent literature [1, 2]. To the best of our knowledge, we are the first to publish experimental results from this type of antenna. The metamaterial array loading the antennas formed a rough cylinder axially enclosed by a patch antenna and a conventional ground plane. The fill ratio, or ratio of the metamaterial radius to the patch radius, was less than one. Given a particular negative permeability metamaterial (spiral rings, in this case), the fill ratio dictates the lower of two resonant frequencies of the antenna. The higher frequency resonance is characteristic of the patch.We observed that each of the antennas radiated at two resonant frequencies, as predicted. The lower frequency resonance disappeared when the metamaterial was removed. We built two versions of this antenna, one with a lower resonance frequency of 365 MHz and higher resonant frequency of 1.8 GHz (Design I) and a second antenna with a lower resonance frequency of 756 MHz and higher resonance frequency of 3.3 GHz (Design II). Because we were interested in reducing the size of patch antennas, we focused on the lower frequency resonances in this work. The antennas’ return loss was measured at -22 dB and -23 dB, the gains were -11 dBi and -13 dBi, and the return loss was less than -10 dB over bandwidths of 4.7% and 1.9% for the lower frequency resonances of Design I and Design II, respectively. The antennas were found to be sensitive to the size of the underlying ground plane. When the ground plane's diameter was seven times that of the patch, the antenna displayed a single smooth broadside radiation pattern in both the E- and H-planes. However, if the ground plane diameter was reduced to only twice that of the patch, the antennas radiated with many nulls and degraded gain. We also predicted the trend of increasing resonant frequency with decreased metamaterial fill ratio. The fill ratio was varied by changing the patch size while maintaining the same metamaterial array. The resonant frequency increased with increasing patch size; an opposite trend to what one would expect without the loading metamaterial. Altering the patch size allows simple tuning during the assembly and test process.  A. Alú, F. Bilotti, H. Engheta, L. Vegni, “Subwavelength, Compact, Resonant Patch Antennas Loaded with Metamaterials”, IEEE Trans. Antennas Propag., 55, 13-25 (2007). F. Bilotti, A. Alú, L. Vegni, “Design of Miniaturized Metamaterial Patch Antennas With Mu-Negative Loading”, IEEE Trans. Antennas Propag., 56, 1640-1647 (2008).
4:45 PM - EE2.7
Nanoparticulate Ruthenium Dioxide Shells on Silica Dielectric Cores—A Single-Unit-Thick Electronic Conductor.
Debra Rolison 1 , Christopher Chervin 2 , Jeffrey Long 1 , Jeffrey Owrutsky 3 , Joseph Melinger 4 Show Abstract
1 Surface Chemistry, U.S. Naval Research Laboratory, Washington, District of Columbia, United States, 2 , Nova Research, Inc., Alexandria, Virginia, United States, 3 Chemical Dynamics and Diagnostics Branch, U.S. Naval Research Laboratory, Washington, District of Columbia, United States, 4 Solid State Devices, U.S. Naval Research Laboratory, Washington, District of Columbia, United States
We recently demonstrated that depositing ~2-nm-thick shells of RuO2 onto dielectric cores (submicron-to-micron silica fibers in filter paper) creates an RuO2(SiO2) extended structure that expresses the impressive properties of ruthenium oxide—high electronic conductivity, high gravimetric capacitive charge storage for pulse power, and fast electron transfer for catalysis—but by using only 0.1 vol.% of RuO2 . The RuO2 is so nanoscopic that 90% of the material is expressed at the surface, making the RuO2 nanoshell the equivalent of a single-unit slice of an electronic conductor. This physically stabilized, single-unit-thick layer of an air- and water-stable metallically conductive oxide affords two distinct opportunities: (1) an additional chemical system (other than graphene) to probe the physics of long-range electron transport under dimensional confinement, but with control of conductivity over three orders of magnitude for the same morphology of ruthenia in the nanoshell and for aspect ratios that range from 10 to >106; and (2) a scalable, atom-efficient form in which to use this material in a broad range of nano-enabled technologies as made feasible by our highly reproducible, self-limiting growth in the z direction using a benchtop-based synthesis. Although a Pt-group metal is being used, the 2009 cost of materials to prepare RuO2(SiO2) paper runs less than $0.30 USD cm-2 of conductive composite.With an object-normalized electron conductivity of ~0.5 S cm-1, RuO2(SiO2) paper is immediately useful as a device electrode and spectroscopic substrate. The anomalously high conductivity of the ruthenia nanoshell (four times that of bulk polycrystalline RuO2 for volume-normalized values), an electron mean free path (at 3.6 nm ) longer than the primary particle size of the deposited oxide, and the closed-loop formulation of the conductor hint that we are only at the beginning of establishing what properties this formulation of a metallic conductor on the nanoscale can exhibit. For example, the measured optical constants of polycrystalline RuO2  indicate that it should exhibit traveling surface plasmon polaritons in the infrared for anisotropic (nanorod) shapes; similar plasmonic character was recently demonstrated for the transparent semiconductor, indium-tin oxide . We anticipate that RuO2(SiO2) core–shell constructs will exhibit plasmonic behavior in the infrared. C.N. Chervin, A.M. Lubers, K.A. Pettigrew, J.W. Long, M.A. Westgate, J.J. Fontanella, D.R. Rolison, Nano Lett. 2009, 9, 2316. K.M. Glassford, J.R. Chelikowsky, Phys. Rev. B 2004, 49, 7107. P. Hones, T. Gerfin, M. Grätzel, Appl. Phys. Lett. 1995, 67, 3078. C. Rhodes, M. Cerruti, A. Efremenko, M. Losego, D.E. Aspnes, J.-P. Maria, S. Franzen, J. Appl. Phys. 2008, 103, 093108.
EE3: Poster Session
Tuesday PM, December 01, 2009
Exhibit Hall D (Hynes)
9:00 PM - EE3.1
The Effect of Refraction Index and Diameter of Porous Alumina of Metallic Wires for Optical Imaging Application.
Guo-Dung Chen 1 , Cheng-Yang Liu 1 Show Abstract
1 , Center for Measurement Standards, Industrial Technology Research Institute, Hsinchu, Taiwan Taiwan
This paper presents the investigation of anodic aluminum oxide (AAO) consisting of metallic wires as a bulk metamaterial for optical imaging application. Anodic aluminum oxide (AAO) is fabricated by electrochemical anodization of aluminum, in which the metallic wires were electrochemically deposited. This work is focused on controlling the diameter of the pores in anodic aluminum oxide (AAO) template in order to observe different negative refractions of the bulk metamaterial. The growth time, temperatures, kinds of electrolyte, working voltage were used to optimize the anodization of alumina. Besides, the effect of working voltage on the diameter of pores in AAO template was also investigated. The surface morphology of alumina film was inspected by scanning electrical microscope (SEM) and the transmission electron microscopy (TEM) was employed to characterize the structure. This material is used to be like an optical lens for microscope on a chip.
9:00 PM - EE3.10
Optical Spectroscopy of a GaAs/AlGaAs Multiple Quantum Well System Near Double Exciton-polariton and Bragg Resonance.
Vladimir Chaldyshev 1 , Denis Sholohov 1 , Alexei Vasil'ev 1 Show Abstract
1 , Ioffe Institute, St.Petersburg Russian Federation
Interaction of electromagnetic waves with excitons in a quantum well (QW) leads to formation of an exciton-polariton that makes resonant changes in the optical properties of the medium. This resonance can be enhanced in the periodic system of QWs, which meets the rule of Bragg diffraction at the frequency of the exciton-polariton state. Under these conditions the electromagnetic coupling of exciton-polaritons in the system of QWs leads to formation of a superradiant mode and a resonant photonic band.In this paper we report the results of optical spectroscopy of the system of GaAs quantum wells separated by AlGaAs barriers. The samples have been grown by molecular-beam epitaxy on semi-insulating GaAs (001) substrates. The QW width was 13, 15 or 20 nm. The number of the QWs was varied from 2 to 60. The AlGaAs barriers were designed to obtain the Bragg resonance near the wavelength corresponding to that of the exciton-polaritons in the QWs. The whole structure was undoped with special care to reduce the density of residual impurities. The samples were optically characterized using reflection and contactless electroreflectance spectroscopy (RS and CERS) at various temperatures, polarizations and angles of the light incidence.The optical reflection spectra have been found to be a result of the interplay of three different contributions, namely (i) the reflection from the air/semiconductor interface, (ii) the Bragg reflection due to periodic modulation of the background indices of refraction being different for the wells and barriers and (iii) the resonant reflection from the periodic system of exciton-polaritons in the quantum wells. The latter contribution was separately studied by CERS in the spectral range covering ground and excited states of the heavy-hole and light-hole excitons. A quantitative analysis of the experimental CERS line shape has been done along with quantum-mechanical calculations, which revealed the characteristic energies and broadening parameters for different exciton-polariton levels. By comparison with theoretical calculations we discuss the radiative and non-radiative contributions to the total broadening. The inhomogeneous non-radiative broadening is found to be mainly associated with the roughness or potential fluctuations at the QW/barrier interfaces. The origin of the radiative broadening is electro-magnetic coupling of exciton-polaritons in the periodic system of the QWs.
9:00 PM - EE3.11
Coexistence of SDW and Pseudo Fine Particle Behaviour.
Ahmad Yazdani 1 , N. Kamali Sarvestani 1 Show Abstract
1 Physics, Tarbiat Modares University, Tehran Iran (the Islamic Republic of)
The spin density wave (SDW) formation is investigated in the distribution of local magnetic felid, manifested by greater exchange distribution in A.C susceptibility measurement. The broad range of transition temperature, as the dynamic of non-equilibrium which is the cause of exchange fluctuation, could be due to the short range interactions, at which the magnetic system is sensitive to physical parameters such as sample shape, magnetic field, and the annealing temperature. While, usually the magnetization is not sensitive to fabrication or heat treatment.The coexistence of both shape (chemo-mechanical character contribution) and magnetic felid (local conduction behaviour contribution), can be the cause of the characteristic and nature of duality of conduction electrons. The sensitive dependence of the magnetic structure - through D.C or A.C magnetic susceptibility - on the external parameters, even heat treatment, is the cause of short range order, by which the strong correlated electron system leads to a decrease in correlation length - where the displacement of magnetic ions in the range of Δx=0.058Å, Δy=0, Δz=0.74Å is investigated. Even though, it will be a question whether the exchange interaction or atomic displacement is the main cause of this phenomenon, the decrease of the correlation length from 3.6Å for Gd to Rc≤3.2 Å should be considered. This effect could decrease the distribution of induced spin polarization in direction of increasing the density of states, as increasing of amplitude of condensation, on which the on-site and inter-site exchange can compete through the strong induced spin polarization. In this case, the effective mass is large and consequently, the magnetic phase transition is derived from condensation energy which is approximately equal to N(Ef)Δ, where Δ is the magnitude of the energy gap opened by the transition, at which the unstable F.M order collapse to AF.M order at TN=48-60 K. Above this gap, system behaves completely paramagnetic. The stabilization effect of magnetic structure can be due to the spin lattice relaxation which is manifested at a critical annealing temperature at which;1- A small doubling can be observed on the intensity line of X-Ray spectrum but not on Yttrium case,2- The magnetic structure stabilizes at the critical topological position of magnetic ions, where the short range unstable F.M breaks or even change to AF.M stable state,3- The existence of some hidden exchange interaction is capable of lowering the entropy of the system while reducing its energy. This is the usual mechanism responsible for re-entrant behaviour of spin lattice relaxation.And above this temperature all internal magnetic fields vanish and the sample behaves completely paramagnet which is independent of the external field.
9:00 PM - EE3.12
Refraction Indices of Structured Materials From the First Principles.
Liudmila Pozhar 1 Show Abstract
1 Physics, University of Idaho, Moscow, Idaho, United States
Recently, a novel, first-principle theoretical approach and synergetic computational methods designed to predict electronic and magnetic transport properties of strongly spatially inhomogeneous systems, including small atomic clusters (such as quantum dots and wires, or QDs and QWs, respectively) and molecules, have been developed. This approach have been derived using a many-body quantum theory formalism - a projection operator method due to Zubarev and Tserkovnikov (ZT) - based on equilibrium, commutatorial two-time temperature Green functions (or TTGFs). There are several significant advantages of this approach, as compared to traditional non-equilibrium two-time thermodynamic and field-theoretical Green function (NGF) methods that are currently used to study electronic and magnetic transport at nanoscale. In particular, the TTGFs are susceptibilities, and thus are directly related to experimentally assessable microscopic charge, spin and microcurrent densities. In the work reported here the equilibrium TTGF approach has been used to derive a fundamental theoretical formula for the tensor of generalized “local” refraction indices (TRI) from the first principles. This correlation uses the TTGF-based expressions for the dielectric permittivity and magnetic permeability, and is applicable to any spatially inhomogeneous systems, including nanostructures, QDs and QWs. The TTGFs necessary to predict TRI can be calculated using quantum statistical mechanical means, modeling and simulations, and experimental data. The most practical and at the same time, accurate TTGF data can be obtained from many-body quantum theory-based, computational modeling.Applications of the theoretical predictions for TRI open new prospects in materials design. In particular, using the theoretical formulae for TRI, (nano)structured materials can be developed to possess both direction- and position-dependent indices of refraction in a desirable wide interval of values, including negative ones.
9:00 PM - EE3.13
Nanoparticle One-Dimensional Photonic-Crystal Dye Laser.
Francesco Scotognella 1 , Daniel Puzzo 2 , Angelo Monguzzi 1 , Diederik Wiersma 3 , Riccardo Tubino 1 , Geoffrey Ozin 2 Show Abstract
1 Dipartimento di Scienza dei Materiali, Universita' di Milano Bicocca, Milano Italy, 2 Department of Chemistry, University of Toronto, Toronto, Ontario, Canada, 3 , European Laboratory for Non-linear Spectroscopy and National Institute for the Physics of Matter, Firenze Italy
Nanoparticle one-dimensional photonic crystals (NP 1D PC) possess high reflectivity arising from Bragg diffraction of light incident on a photonic lattice comprising nanoparticle layers of alternating refractive index. The nanoparticle layers provide mesoporosity, allowing for the introduction of a variety of functional molecules and materials into the intra-nanoparticle voids, creating myriad opportunities for the development of new kinds of optical and optoelectronic devices.In this work, we report the fabrication of a NP 1D PC, made with SiO2 and TiO2 nanoparticles in order to obtain a high refractive index contrast, successively infiltrated with a laser dye (Rhodamine 6G). The realized photonic structure possesses a band gap between 550 and 650 nm. By exciting the sample with a pulsed laser at 532 nm, we demonstrate the lasing emission at around 550 nm, as expected by the distributed feedback (DFB) laser theory. The FWHM of the laser peak is 8 nm and the threshold is 12 μJ cm^-2, one of the lowest threshold reported for a bottom-up nanofabricated DFB laser device.
9:00 PM - EE3.2
Metallodielectric Periodic Nanostructures for Epsilon Near Zero Metamaterials.
M. Joseph Roberts 1 , Simin Feng 1 , Mark Moran 1 , Linda Johnson 1 , Klaus Halterman 1 , Andrew Guenthner 1 Show Abstract
1 Research Department, US Navy NAVAIR NAWCWD, China Lake, California, United States
We report the simulation, fabrication and characterization of metal-dielectric periodic nanostructures with effective epsilon near zero. Previously, we have reported experimental demonstration of diffraction-suppressed propagation through metal-dielectric films [Feng, et al, Applied Physics A 87, 235-244 (2007)] and simulation of resonant transmission through subwavelength ENZ slits [Halterman and Feng, Phys Rev A 78, 021805 (2008)]. For this symposium, we will present new results from such metal-dielectric stacks and newly designed nanostructures. We characterize permittivity of the metal-dielectric periodic structures using NSOM spectroscopy and spectroscopic ellipsometry in the optical regime.
9:00 PM - EE3.3
Compensation for Optical Loss in Metamaterials with Negative Refractive Index.
Jinsong Duan 1 2 , Ruth Pachter 1 Show Abstract
1 , Air Force Research Laboratory, Dayton, Ohio, United States, 2 , General Dynamics Information Technology, Dayton, Ohio, United States
In this study, we report numerical simulations using the finite difference time domain method for the design of optical negative refractive index metamaterials. Semiconductor quantum dots were explored as potential gain materials to compensate for loss in the metal structures. Effects of size, composition and coverage of the quantum dots on loss compensation will be discussed.
9:00 PM - EE3.4
Tunable Microwave Composites Containing Ferromagnetic Microwires.
Julian Gonzalez 1 , Mihail Ipatov 1 , Larissa Panina 2 , Arkady Zhukov 1 , Valentina Zhukova 1 Show Abstract
1 Materials Physics, University of the Basque Country, San Sebastian, Guipuzcoa, Spain, 2 School of Computing, Communications and Electronics, University of Plymouth, Plymouth, Devon, United Kingdom
A possibility to control or monitor the electromagnetic parameters (and therefore scattering and absorption) of composite metamaterials is of great interest for different application such as remote non-destructive testing, remote stress and temperature monitoring, microwave tunable coatings and absorbers. The composites with embedded arrays of metallic wires may demonstrate a strong dispersion of the effective permittivity εef in the microwave range. The use of ferromagnetic wires in composites makes it possible to strongly change the dispersion of εef by modifying the wire magnetic state with external stimulus such as a magnetic field, stress or temperature. The effect of wire magnetism on composite microwave scattering properties was experimentally demonstrated in  for composite with short wires and εef of a resonance type.Here we report novel results on the dependence of the effective permittivity in arrays of Co-based amorphous wires on the external magnetic field applied along the wires. Two types of composites made of lattices of continuous and short–cut wires were prepared and characterized by measuring S-parameters in free space in the frequency band of 0.9-17 GHz from which the effective permittivity was deduced. The continuous wire composites have a plasmonic type dispersion of εef with negative values of its real part below the plasma frequency which is in the GHz range for wire spacing of about 1 cm and wire diameter of about ten micrometers . Both the real and imaginary parts of εef show strong variations with increasing the field owing to the field dependence of the wire impedance which controls the losses in the dielectric response. Above the plasma frequency, the sample becomes practically transparent for microwave radiation as the value of εef tends to be unity and is independent of wire magnetic properties. In the case of cut-wire composites, it is confirmed that their effective permittivity has resonance type dispersion due to the dipole resonance in wires at half wavelength condition. The application of the field broadens the resonance and shifts it towards the higher frequencies. We can conclude that both types of wire composites possess a strong dependence of the effective permittivity on the external magnetic field and are suitable for large scale applications as tunable microwave materials.References:1. D. P. Makhnovskiy, L. V. Panina, C. Garcia, A. P. Zhukov, and J. Gonzalez, Phys. Rev. B, 74, 064205, 20062. Pendry,J. B.,A. J. Holden,W. J. Stewart,and I. Youngs, Phys. Rev. Lett., 76, 4773–4776, 1996.
9:00 PM - EE3.5
Modulation of GaN Light-Emitting Diode With Complementary Metamaterials.
Xiaoxiang Xia 1 , Haifang Yang 1 , Changzhi Gu 1 Show Abstract
1 Laboratory of Microfabrication, The Institute of Physics, Chinese Academy of Sciences , Beijing China
Metameterials (MMs), a new artificially structured composite with exotic electromagnetic (EM) property, has become an attractive topic in recent years. Utilizing the elaborated structured metallic inclusions such as split ring resonators (SRRs) in sub-wavelength scale, the currents in loops are driven by the incident electromagnetic waves, which lead to an L-C resonance and cause the novel features. Recently, a complementary response has been shown in a series of planar metamaterials with SRRs or corresponding inverse planar structures in terahertz region. It indicated the probability of using nanofabricated complementary metamaterials to modulate the photoelectric device such as Light-Emitting Diode (LED). By using electron beam lithography (EBL) and reactive ion etch (RIE), a series of complementary SRRs metamaterials were fabricated on the GaN LED instead of its metal electrode. The new metamaterials layer can modulate the LED spectrum and improve LED performance effectively. More details of the investigation will be reported in the paper.
9:00 PM - EE3.6
Terahertz Magnetic Response from 3D Metamaterials.
Kebin Fan 1 , Andrew Strikwerda 2 , Hu Tao 1 , Xin Zhang 1 , Richard Averitt 2 Show Abstract
1 Department of Mechanical Engineering, Boston University, Boston, Massachusetts, United States, 2 Department of Physics , Boston University, Boston, Massachusetts, United States
The metamaterial composites with tailored permittivity and permeability have given rise numerous electromagnetic behaviors not normally found in nature, such as negative refractive index, superlensing and cloaking. It has been well know how to achieve materials with negative permittivity easily. However, due to the absence of natural materials with negative permeability, the realization of negative permeability response had been a challenge. In this work, we demonstrate 3D split-ring resonators (SRRs) show purely strong magnetic response near 1THz. The Arrayed SRRs with 40um structural size and the gaps perpendicular to the substrate are fabricated on highly resistive silicon by conventional micromachining technology and stand on the substrate. THz-TDS is used to characterize the electromagnetic response of the metamaterials. For normal incidence with magnetic field also normal to the plane of rings, they exhibit a very strong resonance with transmission lower than 20%. Additional simulation results deliver good agreement with the measurements and the circulating current at the resonance confirms the purely magnetic response induced by the magnetic field. This shows that the 3D structures allow for a negative magnetic permeability, which facilitates us to achieve negative-index material at THz. In addition, the negative magnetic permeability can be tuned in terahertz frequency regime by scaling the dimensions of the SRRs.
9:00 PM - EE3.7
Miniaturization of Electromagnetic-Bandgap Structures with Thin Film Dielectrics for Si Interposer Applications.
Koichi Takemura 1 , Noriaki Ando 2 , Hiroshi Toyao 2 , Takashi Manako 1 , Tsuneo Tsukagoshi 2 Show Abstract
1 Device Platforms Research Laboratories, NEC Corporation, Sagamihara Japan, 2 System Jisso Research Laboratories, NEC Corporation, Sagamihara Japan
Electromagnetic-bandgap (EBG) structures have been proposed to be adopted in power distribution network for power noise suppression in high-speed digital and mixed-signal circuits. Because EBG structures embedded in printed circuit boards for the applications generally occupy large area, it is strongly desired to reduce the unit cell size for practical use. We have previously reported the development of inductance-enhanced EBG structures to reduce the unit cell size down to 3 mm for wireless LAN application at 2.4GHz while maintaining a high isolation at the lower frequency of interest and demonstrated their effectiveness. In this paper, we will describe further miniaturization of the unit cell by using thin film technology. Thin film dielectrics enable to downsize the unit cell in combination with inductance-enhanced EBG structures. Consequently, the unit cell size of the EBG structures for the 2.4GHz band can be reduced to less than 1 mm. We are also studying integration of EBG structures into Si interposers. The Si interposers with passive devices are promising candidates for miniaturizing integrated electronic systems and improving electrical properties. Package-level integration of EBG structures with LSIs using Si interposers is expected to improve noise suppression performance because the EBG structures are placed in the immediate area of LSIs which generate power noise. This work was supported by the Ministry of Internal Affairs and Communications of Japan.
9:00 PM - EE3.8
Negative Refraction in Porous Silicon Bragg Mirrors.
Beatriz de la Mora 1 , Rocio Nava Lara 1 , Julia Taguena-Martinez 1 , J. Antonio del Rio 1 , J. Eduardo Lugo 2 , Alejandro Reyes-Esqueda 3 Show Abstract
1 Centro de Investigación en Energía, Universidad Nacional Autónoma de México, Temixco, Morelos, Mexico, 2 Visual Psychophysics and Perception Laboratory, School of Optometry, University of Montreal, Centre Ville, Quebec, Canada, 3 Instituto de Física, Universidad Nacional Autónoma de México, Mexico, D.F. Mexico
Photonic crystals (PC) are structures that show an extraordinary strong nonlinear dispersion at wavelengths close to the band gap. It has beenpredicted that under certain conditions, PC can refract light as if they had a negative refractive index. In photonic bands of one-dimensional PC (Bragg mirrors), light modes propagate with negative effective masses at certain frequencies, and negative refraction may occur near the low frequency edge of the second, fourth and even the sixth bandgaps. Recently, we found evidence of negative refraction in one dimensional PC made of porous silicon. According to the calculated photonic modes, light incidents at the cross section area at 25° and wavelengths of 633 nm and 1350 nm were required to observe negative refraction. Here, we continue the experimental study of these 1 D structure and analyze the refraction at several angles of incidence and wavelengths closed to the predicted one by the theory. Porous silicon multilayers were fabricated by wet electrochemical etching of highly boron-doped silicon wafer type p with orientation (100) and electrical resistivity of 0.001-0.005 Ω-cm. To produce the multilayers, current density applied during the electrochemical dissolution was alternated from 1.5 mA/cm2 to 40 mA/cm2. We study the light propagation through the same multilayer structure at different angles (25°-65°) and for different wavelengths (580 nm -633 nm), and we find that the light coming out in the negative direction does not obey the Snell law.
9:00 PM - EE3.9
Self-Organized Oxide Fibers by the Micro-Pulling Down Method.
Detlef Klimm 1 , Krzysztof Orlinski 2 , Dorota Pawlak 2 Show Abstract
1 , Leibniz Institute for Crystal Growth, Berlin Germany, 2 , Institute of Electronic Materials Technology, Warsaw Poland
It is known that the micro-Pulling-Down (µ-PD) method, that was initially designed for the growth of single-crystalline fibers of a few 100 μm diameter, with length up to several 10 cm, can also be used for the production of micro- and nanostructured eutectic rods. Eutectic self-organization, which is a paradigm of pattern forming, has been recently proposed as potential method for manufacturing of metamaterials while utilizing mechanism of self-organization [1-4]. Usually, eutectics are made or of two metals or of two insulating materials, and for such kind of materials there are the databases of phase diagrams, which are necessary to grow particular material.However considering the metamaterials application, it would be interesting, to create self-organized patterns from components with highly different dielectric properties (eg. metal and insulator). This is not straightforward, as conventional metals (as conductors) do not form easily eutectics with oxides (as insulator) as a result of vanishing miscibility in the liquid state. However some metal oxides like eg. RuO2 show also high conductivity and might be useful to replace normal metals as a basic component of a metamaterial. Other metal oxides with high conductivity recently investigated are based on vanadium oxide and related mixed oxide systems . The system V2O5-MoO3 seems promising for the search for conductor/insulator eutectics, and some theoretical and experimental results are presented for the first time here. The system contains one intermediate compound with about the composition V2MoO8. Simultaneous DTA/TG measurements show, however, that the system is not pseudobinary: Depending on the oxygen partial pressure in the surrounding atmosphere, the melt changes its oxygen content during crystallization by the equilibrium between V5+ and V4+. This equilibrium gives some degree of freedom for manipulating morphology and electrical properties of the solid . Pawlak, et. al., Chem. Mat., 18 (2006) 2450-2457. Kolodziejak et al., Opto-Electron. Rev. 14 (2006) 205-211. Pawlak, Eutectic Fibers with Self-Organized Structures, in Micro-Pulling-Down Technique and Growth of Shaped Crystals, pp. 129-139, Eds: T. Fukuda, V. I. Chani, Springer-Verlag Berlin Heidelberg 2007. Pawlak, Scientia Plena, 4 (2008) 014801. Chandra et al., Solid State Commun. 147 (2008) 83-87. Pawlak, "Manufacturing of self-organized structures" in Handbook of Artificial Materials Vol II: Applications, Taylor and Francis, 2009 – in press.
Nader Engheta University of Pennsylvania
Joshua Le-Wei Li National University of Singapore
Ruth Pachter Air Force Research Laboratory
Minas Tanielian Boeing Research and Technology
Wednesday AM, December 02, 2009
Room 104 (Hynes)
9:30 AM - **EE4.1
Coherent Metamaterials as a Platform for Passive and Gain-assisted Photonic Devices.
Nikolay Zheludev 1 , Vassili Fedotov 1 , Nikitas Papasimakis 1 , Eric Plum 1 , Jinhui Shi 1 Show Abstract
1 Optoelectronics Research Centre, University of Southampton, Southampton United Kingdom
We demonstrate a new class of "coherent" metamaterials, where narrow band EIT-like transmission/reflection resonances correspond to a truly collective response of the entire ordered metamaterial array. The resonances appear as a result of coherent excitations of strongly interacting ordered meta-molecules and are controlled by the size of the array.Coherent metamaterials provide a promising platform for various intriguing applications including slow-light and polarization controlling devices and the “lasing spaser”, which we illustrate in a number of microwave, THz and optical experiments. Also, for the first time we experimentally show that resonant properties and losses in a photonic version of the metamaterial can be controlled through optical gain medium.
10:00 AM - **EE4.2
Bending Back Light: The Science of Negative Index Materials.
Costas Soukoulis 1 2 Show Abstract
1 Dept. of Physics / Ames Lab., Iowa State University, Ames, Iowa, United States, 2 IESL-FORTH / Materials Dept., University of Crete, Heraklion, Crete, Greece
The possibility of negative refraction [1-3] has brought about a reconsideration of many fundamental optical and electromagnetic phenomena. This new degree of freedom has provided a tremendous stimulus for the physics, optics and engineering communities to investigate how these new ideas can be utilized. Many interesting and potentially important effects not possible in positive refracting materials, such as near field refocusing and sub-diffraction limited imaging, have been predicted to occur when the refractive index changes sign. In this talk, I will review our own work on negative refraction in metamaterials, and describe the possible impact of them as new types of optical elements. In particular, I will present theoretical and experimental results on engineered microstructures designed to have chirality with negative index of refraction , electromagnetic induced transparency , and repulsive Casimir forces . Finally, I will report a detailed study of the weakly and strongly coupled fishnets to understand the origin of negative n, as well the mechanism of low losses (that is, high figure of merit (FOM)) for the strongly coupled fishnets . We also study the convergence of the retrieval parameter (e, m, and n) as the number of unit cells (layers) increases. For the weakly coupled structures, the convergence results for n and FOM are close to the single unit cell. As expected, for the strongly coupled structures, hybridization is observed and the retrieval results for n and FOM are completely different from the single unit cell. We demonstrate that the high value of FOM for the strongly coupled structure is due to periodicity effects.Work supported by US-DOE, DARPA, MURI, ONR, and EU (PHOME, and ENSEMBLE projects).References C. M. Soukoulis, M. Kafesaki and E. N. Economou, Adv. Matt. 18, 1941 2006); C. M. Soukoulis, Optics & Photonics News, June 2006, p.16. G. Dolling et. al., Science 312, 892 (2006); Opt. Lett. 31, 1800 (2006); Opt. Lett. 32, 53 (2007). C. M. Soukoulis, S. Linden and M. Wegener, Science 315, 47 (2007). E. Plum et. al., Phys. Rev. B. 79, 035407 (2009); (Selected for a Viewpoint in Physics 2, 3 (2009)); J. Zhou et. al., Phys. Rev. B. 79, 121104(R) (2009); B. Wang, et. al., Appl. Phys. Lett. 94, 151112 (2009). P. Tassin et. al., Phys. Rev. Lett. 102, 053901 (2009). R. Zhao et. al., “Repulsive Casimir Force in Chiral Metamaterials,” Phys. Rev. Lett. (submitted). J. Zhou et. al., “Negative refractive index response of weakly and strongly coupled optical metamaterials,” Phys. Rev. B. (submitted).
10:30 AM - **EE4.3
Plasmonic Optical Negative Index Metamaterials for Modulation and Sensing.
A Bratkovsky 1 Show Abstract
1 , Hewlett-Packard Laboratories, Palo Alto, California, United States
Metal-dielectric metamaterials and systems are of special interest to nanophotonics, since they obviously provide high dielectric contrast, much larger than all-dielectric/semiconductor systems. This makes them promising for applications in dense integrated optical systems, since the mode volume is small. We consider various ways of combining metallic materials for negative dielectric constant and a gain medium to compensate for optical losses. Negative refraction is possible in isotropic medium with both negative permittivity and permeability (“double negative” medium), analyzed by Pafomov in 1959 and Veselago in 1967 . Very attractive feature is their potential for subwavelength imaging .For fast modulation, we have designed the metamateria, which is a stack of metallic films with periodic hole arrays separated by dielectric layers (so-called `fishnet’, FN) for IR range of 1.5-1.7 µm, and fabricated various samples by nanoimprint lithography . The FN supports the `backward’ waves, magneto-plasmon resonance, and have negative index of refraction at IR. We have achieved very fast optical modulation of the effective refractive properties of a Ag/Si/Ag fishnet with the fast ~1ps relaxation time . New very interesting possibility is opened up by exploring the binary mixtures of e.g. lossy metallic nanostructure with gain medium, like e.g. PbSe nanoparticles. We have shown that a binary mixture of quantum dots with silver nanorods makes a lossless negative operation for realistic material structures and parameters feasible .We also explore new possibilities provided by plasmonic nanostructures for sensing, esp. Surface Enhanced Raman Scattering (SERS), where we design plasmonic field enhancers as part of high-performance systems capable of one-molecule detection [6,7]. This effort is to be viewed as a part of silicon photonics that would ultimately need CMOS compatible Si-based light sources, high-index waveguides, high-speed modulators, and photodetectors. *Collaboration with E.Ponizovskaya, I.Naumov, D.Cho, E.Kim, W.Wu, J Li, SY Wang, Z.Li, YR Shen, RS Williams, P. Holmstrom and L. Thylen.1.V.E. Pafomov, Zh. Eksp. Teor. Fiz. 36, 1853 (1959); V.G. Veselago, Usp. Fiz. Nauk. 92, 517 (1967); R.A. Silin and V.P. Sazonov, Delay Systems (Radio, Moscow, 1966), Ch.8.2.J.B.Pendry, " Negative Refraction Makes a Perfect Lens", Phys. Rev. Lett. 85, 3966, (2000);N. Fang, H. Lee, C. Sun, and X. Zhang, Science 308, 534 (2005).3.W. Wu et al., Appl. Phys. A87, 143 (2007); E.Kim, Y.R. Shen, W.Wu, E.Ponizovskaya, Z.Yu, A.M. Bratkovsky, S.-Y. Wang, R.S.Williams, Appl. Phys. Lett. 91, 173105 (2007).4.D.Cho, W.Wu, E.Ponizovskaya, A.M. Bratkovsky, et al. to be published.5.A.M.Bratkovsky et al, Appl. Phys. Lett. 93, 193106 (2008)6.E.V.Ponizovskaya and A.M.Bratkovsky, Appl. Phys. A 87, 175 (2007); A.M.Bratkovsky, E.V.Ponizovskaya, I. Naumov, and Z.Li, to be published.7.A.M. Bratkovsky and A.P. Levanyuk, to be published
11:30 AM - **EE4.4
Frequency-Tunable Metamaterials and Resonant Waveguide Networks.
Harry Atwater 1 Show Abstract
1 Applied Physics, California Institute of Technology, Pasadena, California, United States
Dispersion control and active materials integration have yielded new photonic materials in-cluding i) frequency-tunable near-infrared metamaterials based thermally induced phase tran-sitions in vanadium dioxide and field effect modulation of plasmon propagation in transparent conducting oxides and ii) a new class of resonant photonic materials called resonant waveguide networks. First, we have demonstrated frequency-tunable metamaterials in the near-IR range, from 1.5 - 5 microns, using silver/vanadium oxide hybrid split-ring resonators. Self-aligned, hybrid Ag/VO2 laminate structures allow us to demonstrate optical and geomet-rical engineering of metamaterial devices leading to resonant peak position tuning of 110 nm at near-IR wavelengths. Second, we illustrate resonant frequency tuning in metal-insulator-metal (MIM) plasmonic waveguide resonators employing transparent conducting oxides, such as indium tin oxide, as the dielectric layer. Hall probe measurements show that careful synthesis of transparent conducting oxide films enable carrier concentrations between 1x10^19 and 2x10^21 cm^-3. In this carrier density regime, the plasma frequency can be tuned across the mid- to near-infrared frequencies. By utilizing these structures in an MOS configuration within the MIM waveguide, the properties of the plasmonic mode confined at the metal-oxide interface of the waveguide can be tuned in frequency with an applied voltage of a few volts. Finally, we introduce a new class of artificially designed photonic materials called resonant waveguide networks, with potentially far-reaching implications for materials design as well as the architecture of chip-based guided wave systems. The approach to con-trolling material dispersion in resonant guided wave networks employs photonic elements ar-ranged in a network connected by a discrete set of optically isolated waveguides. These photonic elements are designed so i) power is split equally among the waveguides connected to the element, and ii) so that a primitive or non-primitive unit of connected waveguides in the network acts as a resonator. Here we illustrate a two-dimensional resonant guided wave net-work composed of intersecting metal-insulator-metal waveguides, and discuss how the guided wave network dispersion depends on the waveguide modal properties, waveguide length and network topology. We find that resonant guided wave networks exhibit wave dispersion and photonic bandgaps due to interference effects, similar to photonic crystals. Dispersion arises from distributed localized resonances, similar to metamaterials, but from resonant elements on the wavelength scale, unlike metamaterials.
12:00 PM - EE4.5
The Marriage of MEMS and Metamaterials at THz Frequencies.
Hu Tao 2 , A. Strikwerda 1 , C. Bingham 3 , N. Landy 3 , K. Fan 2 , D. Pilon 1 , D. Shrekenhamer 3 , X. Zhang 2 , W. Padilla 3 , Richard Averitt 1 Show Abstract
2 Mechanical Engineering, Boston University, Boston, Massachusetts, United States, 1 Physics, Boston University, Boston, Massachusetts, United States, 3 Physics, Boston College, Boston, Massachusetts, United States
Metamaterial composites have led to the realization that new possibilities abound for creating effective media displaying functional electromagnetic properties not realized with naturally occurring materials. We have extended these ideas through judicious combination with MEMS technology to create new composites and devices that operate at terahertz frequencies. This includes non-planar flexible composites and micromechanically active structures where the orientation of the electromagnetically resonant elements can be precisely controlled with respect to the incident field. Specifically, we have fabricated multilayer metamaterial structures by pattering gold split ring resonators on highly-flexible ultrathin polyimide to realize resonant absorbers and metamaterial-based wave plates which are quite compact and otherwise difficult to obtain at far-infrared frequencies. In addition, these metamaterial structures are easily patterned over tens of square centimeters, and are flexible enough to be rolled to a diameter of a few millimeters. We have also fabricated arrays of gold split ring resonators on 400 nm thick silicon nitride films where each individual unit cell is a free-standing cantilever. Through temperature tuning, the orientation of the SRRs can be precisely controlled. This, in turn, provides direct control of the electromagnetic response enabling independent access and tuning of the electric and magnetic properties. Such adaptive structures serve as the starting point for the development of a host of new functional electromagnetic devices which take advantage of designed and tunable anisotropy.
12:15 PM - EE4.6
Microfluidics (MF) for Tunable Electromagnetic Metamaterials.
T. Serkan Kasirga 1 2 , Yavuz N. Ertas 2 , Mehmet Bayindir 1 2 Show Abstract
1 UNAM, Bilkent University, Ankara Turkey, 2 Department of Physics, Bilkent University, Ankara Turkey
Recently, dynamically tunable metamaterials attract great interest since some of the potential applications require dynamical control of metamaterial properties. However, conventional split ring resonators (SRR) and wire arrays are not tunable . It has been shown by several researchers that it is possible to tune metamaterial properties in microwave and terahertz region of electromagnetic spectrum, using photoconductive semiconductors , copper wires and ferrite sheets , and liquid crystal . All these methods have some advantages and drawbacks. SRRs formed in MF channels could be an alternative and promising way to create a dynamically tunable metamaterial. A MF metamaterial allows us to use different conducting liquids, individual control of SRRs and some other advantages which will be discussed later. Since it is easy to fabricate and it can change from positive index to negative index within seconds, MF metamaterials would be a good candidate for many possible future applications.In this work our aim is to create a dynamic, tunable LHM using conducting liquids. Here, main reasons for using liquid is simply changing the properties of liquid, i.e. type of the liquid, will lead to change in electric properties, thus resonant frequency of structure can be adjusted. Also a quick transition between positive and negative refractive index will become possible, since characteristic fill up time will be on the order of seconds for most of the liquids. Also one possible application will be related to characterization of materials. If we place a materials between the gaps of SRRs that will change the electric field and a liquid channel will be a good carrier for material in between the gaps . D. R. Smith, et. al., Phys. Rev. Lett. 84, 4184 (2000). A. Degiron, et. al., Opt. Express 15, 3 (2007). Y. He, et. al., J. Magn. Mater. 313, 187 (2007). Qian Zhao, et. al., App. Phys. Lett. 90, 011112 (2007). S. Kasirga, et. al., App. Phys. Lett. (submitted, 2009).
12:30 PM - **EE4.7
Liquid Crystalline Electro- and Nonlinear- Optical Meta-Materials.
Iam choon Khoo 1 Show Abstract
1 Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States
In their various mesophases, liquid crystals possess extraordinarily large optical nonlinearities originating from a variety of mechanisms with characteristic response times ranging from sub-picosecond to milliseconds and longer [1, 2]. The underlying mechanisms include multi-photonic absorptions, density, temperature and order parameters fluctuations and collective molecular reorientation processes. In conjunction with nano-structures or nano-particulates, liquid crystals afford several routes to realizing tunable (electrically or all-optically) metamaterials with many emergent electronics and optical properties and functions. These extraordinary properties enable many optical processes and devices with performance characteristics not possible with other materials. In this presentation, we review the electromagnetic theories underlying these refractive engineering of optical meta-materials. Specifically, periodic nano-structures such as photonic crystals, and randomly distributed nano-particulates in a host media will be treated in details. We will delineate the novel details involved in the synthesis and characterization of these meta-materials, the functional-structure relationships and some exemplary design devices/structures for optical switching, modulation, and optical meta-materials with large birefringence and very broad tunable range [3-7], including some recent experimental observations of ultra-fast [sub-microseconds] all-optical switching in bulk (10's of microns) nematic liquid crystals, and extremely thin (~ 250 nm) cell. References: 1. I. C. Khoo, Liquid Crystals, 2nd Edition (Wiley Inter-Science, NJ 2007). 2. I. C. Khoo, “Nonlinear Optics of Liquid Crystalline Materials,” Physics Report 471, pp. 221-267 . 3. E. Graugnard, J. S. King, S. Jain, C. J. Summers, Y. Zhang-Williams and I. C. Khoo, “Electric field tuning of the Bragg peak in large-pore TiO2 inverse shell opals,” Phys. Rev. B72, 233105 (2005)4. I. C. Khoo, D. H. Werner, X. Liang, A. Diaz and B. Weiner, “Nano-sphere dispersed liquid crystals for tunable negative-zero-positive index of refraction in the optical and Terahertz regimes,” Optics Letts. 31, 2592 (2006). 5. Bossard, J. A., Liang, X., Li, L., Werner, D. H., Weiner, B., Cristman, P. F., Diaz, A., & Khoo, I. C. “Tunable Frequency Selective Surfaces and Negative-Zero-Positive Index Metamaterials Based on Liquid Crystals,” IEEE Transactions on Antennas and Propagation, 56, pp. 1308 - 1320 (2008). 6. I. C. Khoo, J. H. Park, J. D. Liou, “Theory and experimental studies of all-optical transmission switching in a twist-alignment dye-doped nematic liquid crystal,” J. Opt. Soc. Am. B25, pp. 1931-1937 (2008)7. I. C. Khoo, A. Diaz, Justin Liou, D. Werner, J. H. Park, Y. Ma, Junbin Huang, “Liquid crystal nonlinear optical meta-materials,” Mol. Cryst. Liq. Cryst 502, pp 109 – 120 (2009).
Wednesday PM, December 02, 2009
Room 104 (Hynes)
2:30 PM - **EE5.1
Electro- and Magnetoinductive Properties or Reduced Symmetry Metallodielectric Nanoparticles.
Naomi Halas 1 Show Abstract
1 ECE Dept.- MS-366, Rice University, Houston, Texas, United States
Unlike 2D planar structures or 3D materials consisting of stacks of 2D planar structures, the innate 3D character of metallodielectric nanoparticles offers additional freedom in the design and manipulation of electro- and magnetoinductive resonances, the characteristic building blocks of metamaterials. By combining chemical and clean-room fabrication methods, new reduced-symmetry nanostructures not achievable by either approach alone can be designed, fabricated and studied. We will describe several examples where multiple core-shell and partial shell layers are combined to manipulate both the magnetoinductive and electroinductive resonances of these nanoparticles, which are characterized in detail at the single nanostructure and combined nanostructure ensemble level.
3:00 PM - EE5.2
Optical Emission and Energy Transfer in Nanoparticle-Nanorod Assemblies: Potential Energy Pump System for Negative Refractive Index Materials.
Ashish Agarwal 1 , Nicholas Kotov 1 , Alexander Govorov 2 Show Abstract
1 Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States, 2 Department of Physics and Astronomy, Ohio University, Athens, Ohio, United States
Gold nanorods (NRs) in different arrangements represent the most plausible system for the creation of negativerefractive index materials (NIMs) in the optical frequency range. Among other challenges, one of the majorlimitations of present day NIMs is their large amount of energy dissipation which frustrates the restorationof near field modes. To take advantage of exciton-plasmon interactions, an optical system consisting ofsemiconductor nanoparticles (NPs) and Au NRs can continuously pump energy into the NIM resonator.Superstructures with promising properties were achieved by assembly of CdTe nanoparticles on the surfaceof nanorods by using streptavidin-biotin bioconjugation where NPfNR energy transfer occurs with greatefficiency. On the initial layer of bioconjugated NPs, the second layer is formed due to nonspecific interactions,which is manifesting in unusual spectral behavior and dependence of lifetime on NP concentration. By varyingthe ratio of NPs per NR, the amount of energy transfer can be controlled, while the diameter of NPs and wideoverlap offers the possibility to tune the wavelength of the pumping light.
3:15 PM - EE5.3
Novel Polymer-Metal Composite Particles Prepared by Self-Organization.
Hiroshi Yabu 1 4 , Kazutaka Koike 2 , Kiwamu Motoyoshi 2 , Takeshi Higuchi 3 4 , Masatsugu Shimomura 1 3 5 Show Abstract
1 IMRAM, Tohoku University, Sendai Japan, 4 PRESTO, JST, Tokyo Japan, 2 Graduate School of Engineering, Tohoku University, Sendai Japan, 3 WPI-AIMR, Tohoku University, Sendai Japan, 5 CREST, JST, Tokyo Japan
Metal-dielectric hybrid nanostructures are received grate interests due to their potentials for novel photonic materials including left-handed metamaterials. Recently, we found a simple method for preparing block-copolymer and polymer blend particles by evaporation of good solvent from their solution containing poor solvent (Self-ORganized Precipitation (SORP) method). Moreover, lamellae and other phase-separation structures are formed in block-copolymer nanoparticles. In this paper, we show the preparation of nano-structured metal-polymer hybrid particles by combination of the SORP method and electroless plating. Their optical properties will be discussed. Metal-dielectric hybrid nanostructures are received grate interests due to their potentials for novel photonic materials including left-handed metamaterials. However, few effort has been done for developing nanoparticles having well-controlled metal-dielectric hybrid nanostructures. Recently, we found a simple method for preparing block-copolymer and polymer blend particles by evaporation of good solvent from their solution containing poor solvent (Self-ORganized Precipitation (SORP) method). Moreover, lamellae and other phase-separation structures are formed in block-copolymer nanoparticles. In this paper, nanoparticles of metals stabilized with block-copolymer micelles are also embedded i n the phase-separated block-copolymer nanoparticles. Au nanoparticles were prepared in the block-copolymer micelles of poly(styrene-block-2-vinylpyridine) (PS-b-P2VP). PS-b-P2VP micelles were formed in toluene, and then, Au ions are complexed with pyridine moieties of PS-b-P2VP. After reduction of Au ion to Au, Au nanoparticles embedded in PS-b-P2VP micelles (AuNP@PS-b-P2VP) were prepared. The tetrahydrofran (THF) solution of AuNP@PS-b-P2VP was mixed with THF solution of poly(styrene-block-isoprene) (PS-b-PI), water was added into the mixed solution. After evaporation of the THF, the polymer-metal composite particles were prepared. Their internal structures were observed by using a transmission electron microscope (TEM), the particles with phase separation structures were formed. Furthermore, Au nanoparticles were included into the phase-separated particles. Their optical properties will be discussed.
3:30 PM - EE5.4
Fabrication of Large-area Patterned Nanostructures for Optical Applications by Nanoskiving.
Qiaobing Xu 1 , Jiming Bao 2 , Federico Capasso 2 , George Whitesides 1 Show Abstract
1 Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States, 2 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
I will present a new technique – nanoskiving -- that combines thin film deposition of metal on a topographically contoured substrate with sectioning using an ultramicrotome-as a method of fabricating nanostructures that could replace conventional top-down techniques in selected applications. Nanoskiving provides a simple and convenient procedure to produce arrays of structures with cross-sectional dimensions in the 30-nm regime. The dimensions of the structures are determined by (i) the thickness of the deposited thin film (tens of nanometers), (ii) the topography (submicrometer, using soft lithography) of the surface onto which the thin film is deposited, and (iii)the thickness of the section cut by the microtome (>30 nm by ultramicrotomy). The ability to control the dimensions of nanostructures, combined with the ability to manipulate and position them, enables the fabrication of nanostructures with geometries that are difficult to prepare by other methods. The ability to fabricate and manipulate free-standing metallic nanostructures will find applications in the fabrication of materials having negative index of refraction and of three dimensional metamaterials.
3:45 PM - EE5.5
Ultra-Smooth Patterned Metals for Plasmonics and Metamaterials.
Prashant Nagpal 1 , Nathan Lindquist 2 , Sang-Hyun Oh 2 , David Norris 1 Show Abstract
1 Chem. Eng. & Mat. Sci., Univ. of Minnesota, Minneapolis, Minnesota, United States, 2 Electrical & Comp. Eng., Univ. of Minnesota, Minneapolis, Minnesota, United States
Surface plasmons are electromagnetic waves that can exist at metal interfaces due to coupling between light and free electrons. Restricted to travel along the interface, these waves can be channeled, concentrated, or otherwise manipulated by surface patterning. However, because surface roughness and other inhomogeneities have so far limited surface plasmon propagation in real plasmonic devices, simple high-throughput methods are needed to fabricate high-quality patterned metals. We combine template stripping with precisely patterned silicon substrates to obtain ultra-smooth pure metal films with grooves, bumps, pyramids, ridges, and holes. Measured surface plasmon propagation lengths on the resulting surfaces approach theoretical values for perfectly flat films. Using our method, we demonstrate structures that exhibit Raman scattering enhancements above 107 for sensing applications and multilayer films for optical metamaterials.
4:15 PM - **EE5.6
Nanoscale Optics with Negative Index Metamaterials.
Srinivas Sridhar 1 Show Abstract
1 Physics and Electronic Materials Research Institute, Northeastern University, Boston, Massachusetts, United States
Metamaterials with negative optical parameters offer the potential of new nanoscale optical elements that enable new means of controlling the propagation and speed of light. We have developed novel superlenses that beat the diffraction limit, and ultra-short focal length microlenses, at near infrared frequencies, using metamaterials made from metallo-dielectric and semiconductor nanostructures.A new class of indefinite- index metamaterials was demonstrated based on metal-dielectric nanocomposites of vertically aligned Au or Ag nanowires inside dielectric aluminum oxide nanotemplates. The medium is strongly anisotropic with negative permittivity along the nanowire axis. A quantitative model based on effective medium theory is in excellent agreement with optical absorbance measurements, and points to specific composite configurations and wavelength regimes where negative refraction can be achieved . Superresolution imaging at infrared frequencies with sub-wavelength resolution well below the diffraction limit was demonstrated using a nanolens made of this bulk metamaterial. Experimental results are in excellent agreement with ray tracing analysis and a theory of imaging.A generalized photonic crystal superlens nanofabricated in InGaAsP/InP heterostructure demonstrated superlens imaging with sub-wavelength resolution below the diffraction limit of 0.5λ^2 at λ = 1.55μm. An ultra-short focal length plano concave microlens in an InP/InGaAsP semiconductor 2D photonic crystal with negative index of refraction (-0.7) was realized experimentally. We have also demonstrated a planoconcave binary-staircase lens in the InP/InGaAsP platform, which achieves focusing by surface engineering of a bulk medium. A generalized superlens theory gives excellent explanation of wave refraction and image formation in these nanoscale lenses.Controlling the speed of light, in addition to the direction, is a fundamental challenge that can lead to new physical phenomena and applications. We have proposed novel concepts to stop and trap light pulses that utilize anomalous wave propagation in waveguides in semiconductor heterostructures with negative index metamaterial core or cladding. These metamaterial waveguides offer the prospect of on-chip slow light devices where light speeds are reduced by orders of magnitude, enabling ultra-compact optical delay lines and buffers.These nanoscale optical components based upon negative index metamaterials offer the prospect of revolutionary developments in imaging and optoelectronics.For further details see sagar.physics.neu.eduIn collaboration with W.T.Lu, B.D.F.Casse, Y.Huang and S.Savo.Supported by the National Science Foundation and the Air Force Research Laboratories.
4:45 PM - EE5.7
Superresolution Imaging Using Bulk Nanowires Metamaterials at Optical Frequencies.
Bernard Casse 1 , Wentao Lu 1 , Yongjian Huang 1 , Evin Gultepe 1 , Latika Menon 1 , Srinivas Sridhar 1 Show Abstract
1 Physics, Northeastern University, Boston, Massachusetts, United States
We report superresolution imaging of large objects, having sub-λ features, over significant distances (>> λ) with a resolution well below diffraction limit in optics, using a metallic nanolens. The metallic nanolens is composed of high aspect ratio gold nanowires embedded in disordered porous alumina template matrix. This composite medium possesses strongly anisotropic optical properties with negative permittivity in the nanowire axis direction, which enables negative refraction, and transports both far-field and near-field components with very low distortions and with attenuations of the order of < 1 dB/cm. The long-distance image transport mechanism is not based on resonances of materials parameters and thus the subwavelength imaging occurs with low loss (Figure-of-merit (FOM)=-Re(n)/Im(n)~12 (much higher than existing metamaterials)) and in a broad spectral range. This nanolens not only exhibits superior optical properties over existing metamaterials-based lenses, but can also be manufactured in large scale (mm size), thereby offering significant potential for applications in optical storage devices, nanolithography and biomedical imaging. This work was financially supported by the Air Force Research Laboratories, Hanscom through grant no. FA8718-06-C-0045 and the National Science Foundation through grant no. PHY-0457002.
5:00 PM - EE5.8
Eu3+ Spectroscopic Tools for Metamaterials Studies.
Natalia Noginova 1 , Yury Barnakov 1 , Heng Li 1 , Cheng Zhang 1 , Rui Li 1 , Anna Hardy 2 , Mikhail Noginov 1 Show Abstract
1 , NSU, Norfolk, Virginia, United States, 2 , Virginia Tech, Blacksburg, Virginia, United States
Modification of photonic modes in the metamaterial medium and effects of optical magnetism can be studied with use of spectroscopic tools based on rare earth ions having magnetic dipole-related transitions. We discuss fabrication and properties of such spectroscopic probes based on organic systems containing Eu3+ ions with high emission efficiency. Experimental studies of the effects observed in vicinity of metal surfaces and in layered structures are presented. The experimental data are discussed in terms of modification of transition probabilities and account for the interference between directly emitted and reflected light waves
5:15 PM - EE5.9
Host Materials and Geometries for Strongly Enhanced Magnetic Dipole Emission.
Sinan Karaveli 1 , Alexandra Witthoft 1 , Rashid Zia 1 Show Abstract
1 Division of Engineering, Brown University, Providence, Rhode Island, United States
Lanthanide ions, such as trivalent Erbium and Europium, are ubiquitous light emitters in modern optoelectronics. Interestingly, these ions exhibit a number of strong magnetic dipole transitions throughout the visible and near-infrared regime. These resonant magnetic transitions represent natural complements to the artificial magnetic resonances of patterned metallic metamaterials. In this light, significant enhancement to the magnetic dipole transitions in Er3+ and Eu3+ could enable the development of metamaterials with gain. However, although strong Purcell enhancements are regularly achieved for electric dipole transitions, published reports show that only modest (~15-20%) enhancements have been achieved for optical frequency magnetic dipole transitions.We recently demonstrated a 4-fold enhancement of the 5D0 →7F1 magnetic dipole transition in Eu3+ by placing selected metal-organic chelates near planar metal films. This simple geometry allowed us to combine the direct Purcell enhancement of magnetic dipole emission with an indirect enhancement from inhibiting the dominant, 5D0 →7F2, electric dipole transition. Here, we present a detailed study of the host materials and geometries required for stronger magnetic dipole enhancement. Our experimental results for Eu3+ emission within organic (chelates) and inorganic (glass and crystalline) hosts highlight the importance of local field effects and branching ratios on magnetic dipole enhancements. In view of these material findings, we will discuss practical thin-film deposition approaches for the fabrication of integrated optical devices based on magnetic dipole emission.
5:30 PM - EE5.10
Active Magneto-plasmonics in Nanostructured Gold/Cobalt/Gold Multilayer Films.
Vasily Temnov 1 , Gaspar Armelles 2 , Ulrike Woggon 3 , Dmitry Guzatov 4 , Alfonso Cebollada 2 , Antonio Garcia-Martin 2 , Jose-Miguel Garcia-Martin 2 , Tim Thomay 5 , Alfred Leitenstorfer 5 , Rudolf Bratschitsch 5 Show Abstract
1 , MIT, Cambridge, Massachusetts, United States, 2 , Instituto de Microelectrónica de Madrid (CSIC), Madrid Spain, 3 , Institut für Optik und Atomare Physik, TU Berlin, Berlin Germany, 4 , Yanka Kupala Grodno State University, Grodno Belarus, 5 , Department of Physics and Center for Applied Photonics, University of Konstanz, Konstanz Germany
Surface plasmons at noble metal/dielectric interfaces allow for sub-wavelength confinement of optical fields. This property holds the promise for on-chip miniaturization of all-optical circuits based on active plasmonic devices. Here, we present a new concept where the active optical component is a metal/ferromagnet/metal structure. It is based on active magneto-plasmonic microinterferometry, where the surface plasmon wave vector in a Gold/Ferromagnet/Gold trilayer system is controlled via a weak external magnetic field. Application of this new technique allows for a direct measurement of the electromagnetic field distribution inside a metal at optical frequencies and with nanometer depth resolution.
5:45 PM - EE5.11
Towards Flexible Fully Plastic Multilayer DFB Laser.
Angelo Monguzzi 1 , Francesco Scotognella 1 , Francesco Meinardi 1 , Riccardo Tubino 1 Show Abstract
1 Scienza dei Materiali, Univ. Milano Bicocca, Milano, Milano, Italy
The avant-garde development of new smart structures to provide optical feedback mechanisms paves the way to the realization of novel laser emitters. An approach that has been attracting the interest of many researchers is the distributed feedback (DFB), provided by a periodic dielectric modulation along the propagation direction of the light. Such structures, namely photonic crystals, are the optical analogues of electronic semiconductors. In these systems a periodicity in the dielectric constant along one, two or three spatial dimensions comparable to optical wavelengths generates stopgaps, photonic band gaps and slow photons. On the other side, point, line, bend and planar defects give rise to intra-gap states. All plastic light-emitting devices give myriad intriguing advantages, as the possibility of depositing on large-area and flexible substrates. To obtain lasing emission, both an active material that exhibits strong stimulated emission and an optical feedback are necessary. By using organic emitters, the first requirement is fulfilled by a wide state-of-the-art variety of conjugated molecules and polymers. For the second one, the optical feedback, several working photonic structures are reported in literature. Focusing on DFB granted by one dimensional photonic structures, two model systems are extensively reported, respectively corrugated substrates (1D gratings) and multilayer structures. In the case of 1D DFB gratings, several works report structures with very high performance in term of lasing threshold and line narrowing. Nevertheless, lithographic or UV embossing procedures are necessary to make the gratings. Although performances of common multilayer systems are still not comparable with the gratings, multilayer devices are really promising for low-cost technological applications, since they are easy to fabricate, simply by alternating layers of different materials which can be handled also by standard an basic techniques. By following this approach, we report the fabrication and the optical characterization of a flexible fully-plastic multilayer laser (FML). Sample has been realized by alternating layers of two different polymers, one of which doped with an organic dye, on a cellulose substrate. We will demonstrate the stability of the laser peak position upon a strong bending, a feature very interesting in the perspective to realize lasing coating materials, as well as laser plastic tapes.
Nader Engheta University of Pennsylvania
Joshua Le-Wei Li National University of Singapore
Ruth Pachter Air Force Research Laboratory
Minas Tanielian Boeing Research and Technology
Thursday AM, December 03, 2009
Room 104 (Hynes)
9:30 AM - **EE6.1
Symmetry Breaking in Plasmonic Nanostructures.
Peter Nordlander 1 Show Abstract
1 Physics, Rice University, Houston, Texas, United States
Symmetry breaking in a plasmonic nanostructure can drastically change its optical properties by making dark plasmon mode dipole active. Symmetry breaking can also be used to control plasmonic interference and coherence effects such as subradiance, superradiance and EIT and also lead to significantly enhanced electromagnetic field enhancements of relevance for surface enhanced spectroscopies such as SERS and SEIRA. Symmetry breaking will be discussed in several contexts: The breaking of the spherical symmetry of a concentric nanoshell by displacing the dielectric core with respect to the outer surface of the shell (Nanoeggs) or by placing a spherical plasmonic nanoparticle on a dielectric substrate; the breaking of the structural symmetry of small nanoparticle clusters (septamers) ; the breaking of cylindrical symmetry in concentric planar ring-disk systems (Fanocavities). Quite generally we show that symmetry breaking in a nanostructure can enable couplings between bright and dark plasmon modes and result in narrow Fano resonances with line shapes and energies that are exceptionally sensitive to the dielectric environment of the nanostructure. The LSPR sensitivities of the Fanocavity and the septamer are predicted to be among the largest yet for individual nanostructures.  H. Wang, Y. Wu, B. Lassiter, C.L. Nehl, J.H. Hafner, P. Nordlander, and N.J. Halas, PNAS 103(2006)10856 M.W. Knight, Y.P. Wu, J.B. Lassiter, P. Nordlander, and N.J. Halas, Nano Lett. 9(2009)2188 N.A. Mirin, K. Bao, and P. Nordlander, J. Phys. Chem. A 112(2009)4028 F. Hao, Y. Sonnefraud, P.V. Dorpe, S.A. Maier, N.J. Halas, and P. Nordlander, Nano Lett. 8(2008)3983
10:00 AM - EE6.2
Nanogaps in Rectangular Slit Gold Nanohole Arrays for Enhanced Detection Sensitivity.
Ganapathi Subramania 1 , Jeremy Wright 1 , Igal Brener 1 , Shawn Dirk 1 Show Abstract
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Extraordinary transmission (EOT) through nanohole arrays can be effectively utilized for sensing by measuring the shift in the transmitted spectral response due to the presence of chemical or biological agents. The sensitivity to the presence of such agents can be enhanced by localizing the fields to a small volume while maintaining a large enough transmission. Here we describe a system of two dimensional (2D) arrays of rectangular slits (period of 280nm; width=100nm and height = 200nm) where a nanogap as small as 20nm is created in the connecting metal strips along the width of the rectangle. We achieved this by careful dose control during electron beam patterning followed by 50nm thick gold evaporation and lift-off resulting in a uniform array on a glass substrate. We measure a 3X enhancement in transmission through the rectangular array without the nanogap at the transmission resonance of ~ 800nm for light polarized perpendicular to the long axis. The introduction of the nanogap results in a sharp shift in the resonance position to ~ 700nm with a reduction in the enhancement to ~ 1.2 X. The position of the transmission resonance matches well with finite difference time domain simulations. The simulations also reveal large electric field concentration in the nanogap region suggesting the potential for achieving high detection sensitivity to the presence of chem/bio molecules. We will discuss optical response of the nanohole array to test chemical agents as well as discuss the potential for multiplexed on-chip detection. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US DOE’s NNSA under Contract DE-AC04-94AL85000.
10:15 AM - EE6.3
Photonic Molecules for Reproducible SERS Detection.
Stavroula Foteinopoulou 1 2 , Jean-Pol Vigneron 2 Show Abstract
1 , School of Physics, U. of Exeter, Exeter United Kingdom, 2 , FUNDP, Namur Belgium
Nano-sized metal particles can mold and re-shape the electromagnetic (EM) field into sub-diffraction volumes around them while simultaneously enhancing the intensity of the excitation beam by a few orders of magnitude. Actually, this strong scattering capacity of metal nano-particles has been known for centuries and was utilized in colored glass technologies. This dramatic lensing ability of metal nanoparticles stems from the electron plasma oscillations in a very small volume, which are commonly known as particle plasmons or Mie plasmons. Recently, the investigation of such Mie-plasmons has been of high interest, as these are the protagonists in many current problems such as nanoparticle aided sub-diffraction waveguides  or chemical detection with Surface Enhanced Raman Scattering (SERS) . In this talk, we analyze the factors that would lead to suitable nanoparticle based substrates for chemical detection via SERS. Although, it is commonly agreed that the Raman signal is magnified due to the enhancement provided by metal nanoparticles, it is still not understood why SERS signals of the same analytes are frequently irreproducible. Recent work has demonstrated  that an important factor in SERS detection which has been thus far overlooked is the polarization of the enhanced field. Our studies indicate that in general the polarization of the enhancement around metal spheres is very different from the polarization of the excitation source and in addition it is location dependent. On the other hand, nanoparticle dimers fix the polarization of the enhanced field along the dimer axis irregardless the polarization of the excitation source . We discuss how to exploit the properties of such enhancement with known polarization for the design of optimum SERS substrates. S. A. Maier, P. G. Kik and H. A. Atwater, Phys. Rev. B 67, 205402 (2003). P. Stiles, J. Dieringer, N. C. Shah, and R. P. Van Duyne, Ann. Rev. Anal. Chem. 1, 601-626 (2008). P. G. Etchegoin, C. Galloway, and E. C. Le Ru, Phys. Chem. Chem. Phys. 8, 2624–2628 (2006). S. Foteinopoulou, J. P. Vigneron and C. Vandenbem, Opt. Express 15, 4253 (2007).
11:00 AM - **EE6.4
Refractive-Index-Engineering of Multilayer Metamaterials to Achieve Specific Anisotropic and Dispersive Properties.
Douglas Werner 1 , Zhihao Jiang 1 , Pingjuan Werner 1 Show Abstract
1 Electrical Engineering, Penn State University, University Park, Pennsylvania, United States
The rapid development of metamaterials technology coupled with the recent introduction of the transformation optics technique provides RF/optical device designers with an unprecedented ability to manipulate and control the behavior of electromagnetic wave phenomena. This has led to a growing need for design tools which can be used to customize the electromagnetic properties of refractive-index-engineered devices that exploit metamaterials with low, zero, and negative index as well as metamaterials based on transformation optics. For example, having the ability to engineer not only a matched intrinsic impedance (i.e. a matched permeability and permittivity), but also to tailor the anisotropic, inhomogeneous and/or dispersive properties of metamaterials will allow for considerable freedom in customizing their electromagnetic response. This is of critical importance, especially when considering using metamaterials to realize practical devices. A powerful feed-forward design strategy with user-input-defined electromagnetic scattering properties will be presented that has been employed to overcome the shortcomings of previous intuition-based metamaterial design approaches (e.g., high absorption loss, poor impedance match, narrow operating bandwidth, anisotropic angular and/or polarization response). This has been accomplished by combining efficient full-wave modeling approaches together with robust optimization techniques such as genetic algorithms or particle swarms to search a large parameter space for structures that best satisfy the user-defined electromagnetic scattering goals, while also meeting specified fabrication design rules and incorporating the known (measured) dispersion of each constituent material. Moreover, in this paper we present a robust feed-forward design technique that incorporates a generalized inversion algorithm which is capable of extracting the bulk anisotropic material parameters of a multilayered metamaterial stack. Several applications of these versatile nature-inspired optimization techniques ranging from RF to optical will be presented including the custom design of metamaterials with specific anisotropic properties and metamaterials with tailored dispersive properties. Some examples will also be presented and discussed where look-up tables of commercially available constituent materials have been included as part of the feed-forward metamaterial design process.
11:30 AM - EE6.5
Linear to Circular Polarization Conversion in Metal/Semiconductor/Metal Spirals.
Marina Leite 1 , Eyal Feigenbaum 1 , Dennis Callahan 1 , Harry Atwater 1 Show Abstract
1 , CALTECH, Pasadena, California, United States
It is well known that light management requires optical absorption, internal reflection, and light scattering control. Therefore, the search for nanostructures with such unique properties is highly attractive and challenging. Here, we propose a design for a new three-dimensional (3D) heterogeneous photonic material composed of metal and semiconductors, which can enable light trapping and polarization conversion, spontaneous emission enhancement and efficient light coupling in an unprecedented fashion. A structure that potentially embodies these characteristics is a spiral, which can be experimentally achieved by the simple self-rolling of pseudomorphically strained epitaxial multi-layers or thermally-stressed electron beam evaporated layers. These tubes can be formed by the combination of metal and semiconductor thin films, with thickness (usually tens of nanometers) and strain determining the spiral’s cladding width and inner radius, which can vary from 300 nm to 5-7 microns . Today, one of the main limitations in metamaterial’s applications is due to metal losses. Thus, Finite Difference Time Domain (FDTD) simulations were used to determine the ideal material combination and dimensions to reduce losses and improve general optical properties. Metal-insulator-metal (MIM) structures formed by multi-layers of Au/air and Ag/GaAs were examined with inner radius ranging from 300 nm to 3 μm, with 5 to 10 rings and 25 to 100 nm layer thicknesses. A transverse electric (TE) polarized magnetic dipole was used as the light source, with wavelengths ranging from visible to infra-red. FDTD results showed that differently from concentric multi-layers with similar characteristics, spirals have a singular property: the ability of converting light polarization from linear to circular. By adequately modifying the spirals characteristics, conversion efficiency can be optimized. The new geometry can also support propagating surface plasmon polariton (SPP) modes. Furthermore, light can be trapped within the spiral, depending on structure’s inner radius and interlayer spacing. Alternating layers of metal and dielectric can also lead to tubes with widely tunable refractive indices, including negative and sub-unity values. In conclusion, metal/semiconductor and metalodielectric spirals showed a unique set of optical characteristics, such as polarization conversion, allowing novel light manipulation in the nanoscale regime.  Prinz, V. Y. et al. Physica E 6, 828 (2000).
11:45 AM - EE6.6
Fano Resonances in Individual Nono-Stonehenge Cavities.
Niels Verellen 1 2 , Yannick Sonnefraud 3 , Heidar Sobhani 4 , Feng Hao 4 , Pol Drope 1 2 , Peter Nordlander 4 , Stefan Maier 3 Show Abstract
1 , IMEC, LeuVen Belgium, 2 , INPAC-Institute for Nanoscale Physics and Chemistry, Nanoscale Superconductivity and Magnetism and Pulsed Fields Group, LeuVen Belgium, 3 Physics, Imperial College, London United Kingdom, 4 Physics, Rice University, Houston, Texas, United States
Metallic nanostructures consisting of a dolmen-style slab arrangement support multiple Fano resonances. We observe the appearance of Fano resonances in the optical response of such plasmonic nanocavities due to the coherent coupling between their superradiant and subradiant plasmon modes. We investigate the effect of geometry on dispersive coupling between the sharp bonding and broad dipolar mode. The strong dependence of the spectral position and the width of Fano lineshapes on the dielectric gap between the individual structures makes it very useful for sensing of molecular species within the gap, and for applications as unit cells for slow-light metamaterials.
12:00 PM - EE6.7
Dual-band Metamaterial Absorber in the Terahertz Regime.
Hu Tao 1 , Christopher Bingham 2 , Kebin Fan 1 , Daniel Pilon 3 , Andrew Strikwerda 3 , Willie Padilla 2 , Xin Zhang 1 , Richard Averitt 3 Show Abstract
1 Mechanical Engineering, Boston University, Brookline, Massachusetts, United States, 2 Department of Physics, Boston College, Chestnuthill, Massachusetts, United States, 3 Department of Physics, Boston University, Boston, Massachusetts, United States
We experimentally demonstrate a dual band metamaterial absorber with two distinct absorption peaks at 1.4 THz and 3.0 THz. The dual band absorber consists of a dual band electric-field-enhanced resonator and a metallic ground plane, separated by a polyimide spacer. The two resonance responses can be tuned and optimized independently at desired frequencies with comparably high absorptivity as with single band metamaterial absorbers. This feature provides more flexibility in multi-band absorber designs, which is important to develop selective terahertz imaging technology, and can be readily extended to infrared and visible frequency ranges.
12:15 PM - EE6.8
All-dielectric Metamaterials: Simulation of Nanorod and Arrays.
Elena Poklonskaya 1 , Yuriy Poplavko 2 , Gunnar Suchaneck 1 , Gerald Gerlach 1 Show Abstract
1 Institut für Festkörperelektronik, Technische Universität Dresden, Dresden Germany, 2 Microelectronics Department, National Technical University of Ukraine – KPI, Kiev Ukraine
Metamaterials have been in the focus of the scientific research for almost ten years. Most of the metamaterials designs are constructed with the use of metallic elements in order to realize magnetic response. However, there is a major drawback of using metallic inclusions: conduction losses especially at the optical frequency range. All-dielectric metamaterials provide a solution to this problem and allow avoiding these losses. Such artificially structured materials consist of the array of ferroelectric nanorods or nanospheres embedded in dielectric host matrix open the way to realize left-handed behavior at a very high frequency. In this work, we present the implementation of the left-handed rod-type composites consisting of a mixture of two components: the first one, which is called a guest, is made of Ba1-xSrxTiO3 and the second one, the host, is made of SiO2. We specifically chose perovskite ferroelectrics due to their high dielectric permittivity, which is still more than 200 even in the terahertz band. Additional benefit of the perovskite-based dielectric nanostructures is that their properties are completely determined by their physical layout, hence the desired functionality can be obtained by a proper engineering of the dielectric nanostructure.We performed a theoretical study of the electromagnetic wave propagation in all-dielectric rod-type metamaterials. For the first time analytical analysis includes both the scattering effect, well described by the Mie theory and dielectric inhomogeneous structure properties determined using the Maxwell-Garnett approximation. Numerical simulations of the proposed structure were performed in the commercial finite-element partial differential equations solver COMSOL. Complex effective parameters (refractive index, dielectric permittivity and magnetic permeability) were derived from the simulated transmission and reflection behavior of the considered metamaterials. This work was supported by the German Research Foundation (Research Training Group 1401/1) and by the Erasmus Mundus External Co-operation Window Programme of the European Union (E.P.).
12:30 PM - EE6.9
Parallel FDTD Simulations on Optical and Acoustic Metamaterials.
Kenji Tsuruta 1 , Shinji Nagai 1 , Ryosuke Umeda 1 , Tomoyuki Kurose 1 , Noriaki Maetani 1 Show Abstract
1 Electrical and Electronic Engineering, Okayama University, Okayama Japan
We perform large-scale finite-difference time-domain (FDTD) simulation with the aid of efficient parallel-computing algorithms for designing optical and acoustic metamaterials, where either electromagnetic or elastic constants in the materials are artificially modulated via nano/micro-structuring[1,2]. We analyze the electromagnetic response of nanostructured metamaterials to evanescent waves at optical frequency via the FDTD simulations. Effects of the nanostructure on dielectric and magnetic properties are taken into account by introducing the Drude-Lorentz model in the materials dispersion . We have also developed a Recursive-Convolution FDTD (RC-FDTD) algorithm combining with an electronic-structure calculation of simple metal particles for analyzing optical properties of metamaterials. This algorithm enables us to perform realistic modeling of electromagnetic metamaterials by plugging-in the compute-intensive quantum simulations into the FDTD code. Using these computational methods, we assess the materials dependence of light-confinement efficiency in the recently proposed novel structure that combines dielectrics and metamaterials periodically. In the acoustic case, we perform the parallel FDTD simulations of elastic-wave propagations in 2D phononic crystals. The negative refraction of acoustic wave is shown to be achieved via a negative effective mass appeared in their phonon band-structures. By comparing several combinations of materials for metal cylinder and liquid, we analyze the dependence of the band structures on sound speed and density of liquid media . Also we demonstrate that the focal intensity by the lens effect can be optimized by introducing an additional phononic crystal that shields the waves reflected and/or leaked from the source. This work was supported by Grant-in-Aid for Scientific Research on Priority Areas “Nano Materials Science for Atomic Scale Modification 47” from MEXT of JAPAN. R. Umeda, C. Totsuji, K. Tsuruta and H. Totsuji, Mater. Trans 50, 994 (2009). T. Kurose, K. Tsuruta, C. Totsuji and H. Totsuji, Mater. Trans 50, 1004 (2009).