Alexandra Boltasseva, Purdue University
Dragomir Neshev, Australian National University
Jie Yao, University of California Berkeley
Xiaobo Yin, University of Colorado Boulder
Symposium Support NKT Photonics, Inc.
HH2: New Metaphotonic Designs and Fabrications II
Monday PM, November 30, 2015
Hynes, Level 2, Room 204
2:30 AM - *HH2.01
On the Macroscopic Description of Optical Stress in Metamaterials
Che-Ting Chan 1 Shubo Wang 1 Wujiong Sun 1 2 Jack Ng 3
1Hong Kong Univ of Samp;T Kowloon Hong Kong2State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Collaborative Innovation Center of Advanced Microstructures, Fudan University Shanghai China3Department of Physics and Institute of Computational and Theoretical Studies, Hong Kong Baptist University Hong Kong Hong KongShow Abstract
In the area of metamaterial research, it is frequently assumed that effective medium parameters provide all the information necessary to determine the light-matter interaction. But even if the effective medium parameters can describe faithfully how the material can manipulate wave in the long wavelength limit, can the same set of parameters describe faithfully how the wave can manipulate the material? It is known that the total electromagnetic induced force acting on a metamaterial can be calculated using the Maxwell stress tensor if the light scattering property of the metamaterial can be described by standard effective medium parameters. However, we show that the optical stress inside a metamaterial systems cannot be determined by the information of effective permittivity and permeability and it can only be correctly calculated using the Helmholtz stress tensor which takes into account of electrostrictive and magnetostrictive effects. Using multiple scattering theory, we derived for the first time the analytical formulas for electrostrictive/magnetostrictive tensors for two dimensional all dielectric metamaterial systems, which are found to depend explicitly on the symmetry of the underlying lattice of the metamaterial as well as a local effective wave vector. These analytical results enable us to calculate light-induced body forces inside a composite system using the Helmholtz stress tensor within the effective medium formalism in the sense that the fields used in the stress tensor are those obtained by solving the macroscopic Maxwell equation with the microstructure of the metamaterial replaced by an effective medium. The optical stress induced by an external light source at the boundary of two metamaterials is also subtle. We investigate the optical stress induced at the interface formed by two kinds of metamaterials and it is found that the stress is strongly affected by the electrostriction and magnetostriction effects. We show that the symmetry of the underlying lattice can dramatically influence interface stress to the extent the optical stress in the interfacial area is in fact "indeterminate", in the sense for given values of effective permittivity and permeability, the interfacial stress is unknown unless we know the microscopic details or their manifestations through electrostrictive tensors. Related to this problem, we find that light in a negative-index material background in general does not pull an object immersed in it.
3:00 AM - HH2.02
Graphene-Enabled Active Metamaterials
Osman Balci 1 Ertugrul Karademir 2 Semih Cakmakyapan 3 Nurbek Kakenov 1 Emre Ozan Polat 4 Seung Hyun Hur 5 Ekmel Ozbay 1 Coskun Kocabas 1
1Bilkent University Ankara Turkey2Trinity College Dublin Ireland3University of California LA Los Angeles United States4University of Glasgow Glasgow United Kingdom5University of Ulsan Ulsan Korea (the Republic of)Show Abstract
Metamaterials bring subwavelength resonating structures to overcome the limitations of conventional matter. The realization of active metadevices requires electrically reconfigurable components operating over a broad spectrum with a wide dynamic range. The existing capability of metamaterials, however, is not sufficient to realize this goal. Here, using large area graphene capacitors incorporated with metallic split ring resonators, we demonstrated electrically controlled metadevices on large-area flexible substrates. In this device architecture, metallic resonators are capacitively coupled to the graphene electrodes that introduce voltage-controlled dissipation. Electrostatic tuning of charge density on graphene in the order of 1014 cm-2 enabled us to switch the resonance behavior of the split ring resonators by 50 dB with an operation voltage of 2V. Large modulation depth, simple device architecture, and mechanical flexibility are the key attributes of the graphene-enabled metadevices that could find a wide range of applications ranging from active signal processing to switchable cloaking.
3:15 AM - HH2.03
Enhancing Optical Signals of Chiral Metamaterials via Nonlinear Excitation
Sean P Rodrigues 1 Yonghao Cui 1 Shoufeng Lan 1 Lei Kang 1 Wenshan Cai 1
1Georgia Inst of Technology Atlanta United StatesShow Abstract
As natural chiral materials demonstrate limited circularly dichroic contrasts, enhancement of these polarization dependent signals has long been the focus of chiral metamaterial research. By manipulating the geometric chirality of resonant plasmonic nanostructures, we are capable of enhancing light confinement to amplify chiral modified, nonlinear signals from quantum emitters. The metamaterial demonstrates a linear transmission contrast of 0.5 between left and right circular polarizations and a 20× contrast between second harmonic responses from the two incident polarizations. Nonlinear and linear response images probed with circularly polarized lights show strongly defined contrast. As a second set of experimentation, the chiral center of the metamaterial is opened, providing direct access to place emitters to occupy the most light-confining and chirally sensitive regions. The resulting two-photon emission profiles from circularly polarized excitation displays mirrored symmetry for the two hybrid enantiomer structures. The efficiency of the nonlinear signal directly correlates to the chiral resonance of the linear regime. The nonlinear emission signal is enhanced by 40× that of the emitters not embedded in the metamaterial and displays a 3× contrast for the opposite circular polarization. Such manipulations of nonlinear signals with metamaterials open pathways for diverse applications where chiral selective signals are monitored, processed, and analyzed.
3:30 AM - HH2.04
Tunable Metasurfaces Based on Selective Modification of Phase Change Materials
Shuyan Zhang 2 Jura Rensberg 1 You Zhou 2 Jochen Kerbusch 3 Shriram Ramanathan 2 Carsten Ronning 1 Federico Capasso 2 Mikhail Kats 2 4
1Friedrich-Schiller-Universitauml;t Jena Jena Germany2Harvard University Cambridge United States3Helmholts-Zentrum Dresden-Rossendorf Dresden Germany4University of Wisconsin Madison United StatesShow Abstract
Tunable optical metamaterials and metasurfaces are an emerging frontier, with promising applications including optical modulation, routing, and beam steering. Dynamic control in such meta-devices can be achieved by incorporating active media, e.g. liquid crystals or phase change materials, into the optical structures. Vanadium dioxide (VO2), a prototypical phase change material, has a thermally induced insulator-metal transition that results in a considerable change in its optical properties. It has been shown that the complex refractive index of VO2 changes drastically during phase transition.
Here we demonstrate tunable metasurfaces created using defect engineering via ion irradiation through lithographically defined masks, which locally modifies the phase transition properties on a subwavelength scale. Our metasurfaces consist of irradiated and unirradiated (intrinsic) VO2 regions in a square checkerboard arrangement on a sapphire substrate. The phase transition properties of the metasurface are determined by the ion fluence and the duty cycle of the irradiated regions. Naively one might expect the reflectance of our metasurface to be the average of the reflectance values of the irradiated and intrinsic VO2. Instead we observe an effective response of the metasurfaces, with an “effective phase transition temperature” between the phase transition temperature of the irradiated and intrinsic VO2. This is due to the subwavelength nature of our patterned features. Hence we can treat the patterned VO2 film as an effective medium which has a well-defined temperature- and wavelength-dependent complex refractive index. We apply effective medium theory to model the behavior of our metasurfaces, and observe good agreement with the experimental results. By combining defect engineering with electron-beam lithographic patterning techniques, we can design effective media with engineered anisotropy and gradient indices. Our approach will be broadly applicable to the development of tunable optical meta-devices.
4:15 AM - *HH2.05
Nano-Optomechanical Dielectric Metasurfaces Reconfigurable with Light
Artemios Karvounis 1 Jun-Yu Ou 1 Davide Piccinotti 1 Weiping Wu 1 Eric Plum 1 Kevin F. MacDonald 1 Nikolay I. Zheludev 1 2
1Univ of Southampton Southampton United Kingdom2Nanyang Technological University Singapore SingaporeShow Abstract
We report on the realization of ultrathin free-standing all-dielectric metasurfaces, with sharply resonant optical properties in the near-infrared (telecoms) wavelength range, in which the optical forces generated among constituent elements are sufficient to induce reversible nanoscale structural deformation. With mechanical Eigenfrequencies in the hundreds of megahertz range, the optomechanical response of such structures provides for fast, strongly nonlinear tuning of optical properties at µW/µm2 intensities.
4:45 AM - HH2.06
Super-Cell Chirality in Gap-Plasmonic Metasurfaces
Amr Shaltout 1 Jingjing Liu 1 Alexander V. Kildishev 1 Vladimir Shalaev 1
1Purdue West Lafayette United StatesShow Abstract
We present a novel methodology to implement metasurfaces that realize the optical properties of chiral media which possess differential operation with respect to left- (LCP) and right-circular polarization (RCP). Chirality is very recurrent in biological media and organic compounds. These compounds have molecules which don&’t superimpose onto their mirror image lifting the degeneracy between LCP and RCP causing the chiroptical response. Thus, generating and sensing optical chirality is valuable to stereochemistry and molecular biology in addition to its electrodynamic applications. However, the chiroptical effect is generally weak in natural crystals and detectable only when strong phase differences between LCP and RCP accumulate over a long optical path. Strong chiroptical effects have been demonstrated in metamaterials using 3D nano-structures with broken mirror symmetry. Yet, they are complicated to implement because they require fabrication of multi-layers with angular rotations of nano-structures along successive layers. Here, we present a simplistic and efficient technique to produce chiroptical effects with gap-plasmonic metasurfaces. A planar array of metallic antennas is fabricated on top of a metallic film reflector and spaced by a dielectric layer. The metal\dielectric\metal sandwich excites slow gap-plasmonic waves that cause a significant phase and polarization change to the back-reflected beam. As a result of antennas&’ anisotropy, the metasurface responds differently to RCP and LCP. Through introducing a phase-shift between the reflected LCP and RCP components of light, the metasurface performs the chiral response of rotating polarization angle (PA) around propagation direction. We implement two metasurfaces that rotate PA of linearly polarized light by 450and -450, respectively. The structure doesn&’t require using complex chiral antennas. We use simple rectangular antennas, and the chiral response is obtained through superposition of reflected beam from a 16-antennas supercell by careful design of location and orientation of each antenna. We obtain a chiral effect that depends on the supercell structure rather than the properties of composite materials. Therefore, the operation is very tolerant against fabrication inaccuracies and\or temperature effects, and high quality results are experimentally obtained. Thus, gap-plasmonic metasurfaces can provide simple, compact and efficient technology for applications include bio-sensing, DNA structural analysis, crystallography, and secure quantum communications.
5:00 AM - HH2.07
Bound State in the Continuum Optical Devices
Boubacar Kante 1
1Univ of California-San Diego La Jolla United StatesShow Abstract
Symmetries play a fundamental role in physics and devices physics. In this talk, I will discuss the fundamental role of symmetries at the nanoscale resonant level in constructing nanophotonics optical devices. I will in particular discuss the possibility to construct new optical modes that do not decay despite residing the continuum of radiation modes. These modes, called bound states in the continuum, are very peculiar modes with topological properties that can enhance the functionality of nanophotonics optical devices. Their design, fabrication and characterization will be presented.
5:15 AM - HH2.08
Visible-Frequency Hyperbolic Metasurface
Robert C. Devlin 1 Alexander A. High 3 2 Alan M. Dibos 1 Mark Polking 3 Dominik C Wild 2 Janos C Perczel 4 Nathalie P de Leon 3 2 Mikhail D Lukin 2 Hongkun Park 3 2
1Harvard University Cambridge United States2Harvard University Cambridge United States3Harvard University Cambridge United States4Massachusetts Institute of Technology Cambridge United StatesShow Abstract
Metamaterials are artificial media that produce optical phenomena not present in naturally occurring materials. However, three-dimensional (3D) metamaterials suffer from extreme propagation losses, limiting their utility. Two-dimensional (2D) metasurfaces and, in particular, hyperbolic metasurfaces (HMSs) for propagating surface plasmon polaritons, have the potential to alleviate this problem. Because SPPs are guided at a metal-dielectric interface (rather than passing through metals), these HMSs have been predicted to have lower loss while still exhibiting phenomena observed in 3D metamaterials.
We report the first experimental realization of a hyperbolic metasurface  formed by lithography and etching nanostructures into sputter-deposited, single-crystalline silver films. The resulting devices display broadband negative refraction and diffraction-free propagation. Additionaly, we find that the HMS exhibits strong, dispersion-dependent spin-orbit coupling, enabling polarization- and wavelength-dependent routing of chiral SPPs. Because we begin with extremely low-loss silver films[1,2], the measured propagation distances of up to 30 mu;m in the HMS shows that the 2D nature of our devices coupled with the single-crystalline silver films offers a substantial, one to two orders of magnitude improvement over 3D metamaterials. These results provide tools for implementing high-performance plasmonic nanostructures with widespread conventional and quantum optics applications.
 Alexander High*, Robert C. Devlin*, Alan Dibos, Mark Polking, Dominik S. Wild, Janos Perczel, Nathalie P. de Leon, Mikhail D. Lukin and Hongkun Park. Visible-frequency hyperbolic metasurface. Nature522, 192-196 (2015). *equal contribution.
 S. Kolkowitz*, A. Safira*, A. A. High, R. C. Devlin, S. Choi, Q. P. Unterreithmeier, D. Patterson, A. S. Zibrov, V. E. Manucharyan, H. Park, M. D. Lukin. Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit. Science347, 1129 (2015)
5:30 AM - HH2.09
Multifunctional Multiwavelength QD-Nanoparticle Integrated All-Dielectric Optical Circuits: On Chip Focusing and Guiding
Swarnabha Chattaraj 1 Anupam Madhukar 2 3
1University of Southern California Los Angeles United States2University of Southern California Los Angeles United States3University of Southern California Los Angeles United StatesShow Abstract
Optical metamaterials are being exploited to manipulate light on the nanoscale but integrating such metamaterial structures with a nanoscale source such as a quantum dot (QD) to gain integrated multiple functions such as enhancement of QD excitation and/ or emission rates and directing the emitted photons on to a waveguide in an on-chip optical system remains a challenge. Past efforts have been largely focused on individual functions such as: (i) enhancement of excitation and/ or emission rates via incorporation of the QD in a photonic cavity ;(ii) guiding of the emitted photons via appropriate placement of the QD by an antenna directed towards (iii) a lossless waveguide. Here we propose and analyze a novel design that incorporates these multiple functions simultaneously at multiple wavelengths into an architecture comprising a QD in a coupled dielectric nanoparticle resonator based optical circuit.
We realize these multiple functions by tailoring the wavelengths of the magnetic and electric multipole modes in high index dielectric nanoparticles as a function of size, shape and material parameters to control their coupling to the electronic states in the QD at the designed excitation and emission wavelengths. The optical response of the system is analytically modeled using the multipole expansion method  based on classical electromagnetism. We present specific results for a system comprising TiO2 nanoparticle optical resonators and a QD excited at 532nm and emitting at 980nm. The nanoparticle radius and separations are chosen such that the magnetic hexapole (TE3,1) mode is in resonance at the excitation wavelength of 532nm to provide local electric field enhancement at the QD while simultaneously the magnetic dipole (TE1,1) and electric dipole (TM1,1) modes are in resonance at the QD emission at 980nm to provide guiding. In this case we find a 20-25 fold enhancement of electric field intensity at the QD at the excitation wavelength along with simultaneous Purcell enhancement, guiding and on-chip lossless propagation at the emission wavelength. The different functionalities in our design show sufficient robustness with respect to fabrication tolerances such as nanoparticle positions which, along with the inherent lossless nature of the dielectric material makes the design suitable for scaling. Our generic analysis of the multipole resonances and light-matter interactions makes this approach readily applicable to optimization of dielectric materials and architectures relevant to optical and other wavelength regimes.
 S. Buckley et.al. Rep. Prog. Phys. 75, 126503 (2012).
 A. E. Krasnok et.al. Optic Express 20, 20599 (2012).
 A. Yariv, et.al. Optic Letters 24,11 (1999).
 J. M. Gerardy et.al. Phys. Rev. B 25, 6 (1982).
HH1: New Metaphotonic Designs and Fabrications I
Monday AM, November 30, 2015
Hynes, Level 2, Room 204
9:15 AM - HH1.01
Investigating Bright and Dark Plasmons with All k Vectors and All k Vectors and Energies with Multiprobe Excitation and Scattering/Collection Near-Field Scanning Optical Microscopy
Rimma Dekhter 2 Aaron Lewis 1
1The Hebrew University of Jerusalem Jerusalem Israel2Nanonics Imaging Jerusalem IsraelShow Abstract
New apertured and apertureless methods will be described with relationship to the excitation and detection of dark and bright surface plasmon polaritons. The methods are based on interrogating meta surfaces with multiple probes. As has been very elegantly demonstrated by Xifeng Ren et al, [Applied Physics Letters 98, 201113 (2011)] an apertured Near-field Scanning Optical Microscopy (NSOM) probe acts as a point source of surface plasmon polaritons with a deterministic position and minimum requirement for the light source. On the other hand Dobman et al, [Adv. Optical Mater. 2014, DOI: 10.1002/adom.201400237 ] have shown that a second type of bound surface plasmon polariton, that cannot be excited from the far-field, propagates well across a metasurface. Such a bound plasmon polariton can only be excited, if light is used, from a near-field probe which produces all k vectors. Furthermore, point excitation of plasmons without background light and with all k vectors and all energies also will be reported using tunneling probes incorporated into a multiprobe system with scattering or collection NSOM for mapping the transport of plasmon polariton propagation on a variety of meta surfaces. All of these probes are constructed to allow for contact of one probe with another which is readily accomplished.
9:30 AM - *HH1.02
Spinoptical Gradient Metasurfaces
Erez Hasman 1
1Technion-Israel Inst. of Technology Haifa IsraelShow Abstract
Photonic gradient metasurfaces are ultrathin electromagnetic wave-molding metamaterials that provide a route for realizing flat optics. Recently, we reported on a novel class of metasurfaces - spinoptical metamaterials - which gives rise to a spin-controlled dispersion due to the optical Rashba effect. The optical spin as an additional degree of freedom offers controlled manipulation of spontaneous emission, absorption, scattering, and surface-wave excitation. Spin-symmetry breaking in nanoscale structures caused by spin-orbit interaction, leading to a new branch in optics - spinoptics is presented. The spin-based effects offer an unprecedented ability to control light and its polarization state in nanometer-scale optical devices, thereby facilitating a variety of applications related to nano-photonics. However, the up-to-date metasurface design, manifested by imprinting the required phase profile for a single, on-demand light manipulation functionality, is not compatible with the desired goal of multifunctional flat optics. Here, we report on a generic concept to control multifunctional optics by disordered (random) gradient metasurfaces with a custom-tailored geometric phase. This approach combines the peculiar ability of random patterns to support extraordinary information capacity, and the polarization helicity control in the geometric phase mechanism, simply implemented in a two-dimensional structured matter by imprinting optical antenna patterns. By manipulating the local orientations of the nanoantennas, we generate multiple wavefronts with different functionalities via mixed random antenna groups, where each group controls a different phase function. Disordered gradient metasurfaces broaden the applicability of flat optics as they offer all-optical manipulation by multitask wavefront shaping via a single ultrathin nanoscale photonic device.
10:00 AM - HH1.03
On-Chip CMOS-Compatible All-Dielectric Zero-Index Metamaterial
Yang Li 1 Orad Reshef 1 Mei Yin 1 2 Philip Alejandro Munoz 1 Daryl I Vulis 1 Shota Kita 1 Marko Loncar 1 Eric Mazur 1
1Harvard Univ Cambridge United States2Peking University Beijing ChinaShow Abstract
On-chip metamaterials with a refractive index of zero shows extreme physical properties such as infinite phase velocity and wavelength. It also has several potential integrated-photonics-related applications including super-couplers, surface emitting lasers, and phase-mismatch-free nonlinear optics. Silicon-on-insulator (SOI) platform received much attention recently due to its compatibility with complementary metal-oxide-semiconductor (CMOS) technology, which makes the mass production of photonic devices reliable. Current implementations of on-chip SOI-based zero-index metamaterials involve either metallic structures or high aspect-ratio silicon pillars, which require many processing steps, and is complicated to integrate with other photonic devices on a standard SOI wafer. Additionally, metamaterials involving metallic structures cost highly.
Here, we design an on-chip zero-index metamaterial consisting of square array of air-holes in the 220-nm thick top-silicon layer of a standard SOI wafer. This structure can be fabricated through the single-step E-beam lithography and fully-etching, which reduces the processing steps and the fabrication difficulties significantly.
Simulated effective permittivity and permeability cross zero simultaneously and linearly at the design wavelength of 1550 nm, with a finite effective impedance. Computed band structure shows that this epsilon-and-mu-zero behavior corresponds to a Dirac-cone dispersion at the center of the Brillouin zone (Gamma point), indicating a relatively isotropic zero index. This Dirac-cone dispersion is formed by the degeneracy between a quadrupole mode and two degenerate dipole modes at the Gamma point. All these results indicate that the zero index of this metamaterial is low-loss, isotropic and with a good impedance matching to free space and standard optical waveguides.
To directly demonstrate the zero index of this metamaterial, we plan to measure the refraction of a prism made of this metamaterial. We also plan to retrieve the complex index and impedance of the metamaterial from the complex transmission and reflection coefficients measured using on-chip Mach-Zehnder-interferometer-based setups.
In conclusion, we demonstrate an on-chip CMOS-compatible all-dielectric metamaterial with a low-loss, isotropic, and impedance-matched zero index at 1.55 um.
10:15 AM -
10:30 AM - HH1.05
Froehlich Resonance in an AsSb-AlGaAs Metamaterial
Vladimir V. Chaldyshev 1 2 Vitalii Ushanov 1 Valerii Preobrazhenskii 3 Mihail Putyato 3 Boris R. Semyagin 3
1Ioffe Institute Saint Petersburg Russian Federation2Peter the Great St.Petersburg Polytechnic University Saint Petersburg Russian Federation3Institute of Semiconductor Physics Novosibirsk Russian FederationShow Abstract
When an array of small metallic particles is embedded into a dielectric matrix one should expect a pole in the polarizability of the medium at certain energy, when the negative real part of the dielectric function of the metal compensates the double value of the positive real part of the dielectric function of the surrounding dielectric material. This gives rise to so called Froehlich resonance in the optical properties of such metamaterial.
We investigated a resonance in optical absorption, which originates from localized plasmon excitations in a self-organized system of metal AsSb nanoparticles embedded in a semiconductor AlGaAs matrix.
The AsSb-GaAlAs metamaterial was produced by a low-temperature molecular-beam epitaxy on the (001) GaAs substrates followed by a high-temperature annealing. Our transmission electron microscopy study revealed a system of almost spherical AsSb inclusions in the crystalline AlGaAs matrix. The diameter of the inclusions was 4-7, 5-8 and 6-9 nm after annealing at 400, 500 and 600C, correspondingly. The filling factor was constantly 0.17%.
The Froehlich plasmon resonance in our metamaterial was revealed at 1.48 eV with a bandwidth of 0.18 eV. The absorption coefficient within the resonant band was as large as 9000 cm-1. No significant changes in the parameters of the resonance have been observed for different particle sizes, which is consistent with Mie scattering theory. In theoretical calculations we used well documented data for the dielectric properties of AlGaAs and Drude model for the electron system of the metal AsSb nanoinclusions. A reasonably good description was achieved with plasmon resonance energy of 7.38 eV and damping time of 3 fs in bulk AsSb, w