Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session X21: Nanostructures and Metamaterials -- Nonlinear EffectsFocus
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Sponsoring Units: DMP Chair: Sui Yang Room: BCEC 157B |
Friday, March 8, 2019 8:00AM - 8:36AM |
X21.00001: Controlling emission and nonlinearity with plasmonic metamaterials Invited Speaker: Viktor Podolskiy Metamaterials encompass a broad class of structures whose electromagnetic response is driven by their geometry in addition to their composition. Plasmonic nanowire metamaterials provide a platform for engineering optical response from dielectric to epsilon-near-zero to strongly anisotropic (hyperbolic) regimes. Importantly, these metamaterials support exotic additional electromagnetic waves. From the effective medium standpoint, these waves can be described by nonlocal (spatially dispersive) permittivity. In this talk we present a theory of nonlocal electromagnetism in nanowire metamaterials and analyze the effect of optical nonlocalities on spontaneous emission and nonlinear optics in these composites. We show that additional electromagnetic modes can drastically increase local density of photonic states, causing significant enhancement of decay rates. We also demonstrate that plasmonic composites can be used to engineer bulk second-order nonlinearities, with amplitude of effective nonlinear polarizability comparable to that in LiNb and KDP. Finally, we show that geometry of nanowire composites can be used as an important parameter to control polarization properties of structural second harmonic generation. |
Friday, March 8, 2019 8:36AM - 8:48AM |
X21.00002: Deterministic modal control of second-harmonic generations in a plasmonic two-wire transmission-line Tzu-Yu Chen, Julian Obermeier, Markus Lippitz, Chenbin Huang A plasmonic two-wire transmission-line supports two modes, one with surface plamon fields strongly confined in the gap, the other loosely guided by the wire perimeters. Using the modal asymmetry provided by the loosely guided mode, we demonstrate a new way to allow second-harmonic generation (SHG). Moreover, we demonstrate both experimentally and theoretically the ability to deterministically control the SHG modes. |
Friday, March 8, 2019 8:48AM - 9:00AM |
X21.00003: WITHDRAWN ABSTRACT
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Friday, March 8, 2019 9:00AM - 9:12AM |
X21.00004: Effects of Spatial Confinement on Nonlinear Light Emission from Plasmonic Nanostructures Robert Lemasters, Hayk Harutyunyan Photoluminescence (PL) from plasmonic nanostructures with spatial inhomogeneities have been demonstrated to exhibit an interesting nonlinear character [1,2]. Previous studies on rough metal films have shown the PL signal to have a wavelength dependent nonlinear scaling exponent which increases linearly with emitted photon energy [2]. This result was attributed to recombination of nonequilibrium electrons within the conduction band mediated by the breakdown of momentum restrictions as a consequence of the spatial inhomogeneities of the surface. However, in these experiments the spatial structures under study were random in nature. Thus, the degree of momentum breakdown and its effect on PL are not obvious from these results. To address this, we use a geometry of Au nanowires separated from Au films by nanometric SiO2 layers via ALD to control the degree of spatial confinement of the resonant gap-mode plasmons. Our results indicate that the PL signal from this nanoprecise system has a nonlinear power law exhibiting two distinct linear regimes, differing from that of rough films. This indicates that the physical mechanism of the nonlinear PL signal originating from thermalized hot electron relaxation needs to be revisited. |
Friday, March 8, 2019 9:12AM - 9:24AM |
X21.00005: Bistable shallow arches: a new building block for nonlinear mechanical metamaterials Eleonora Tubaldi, Gabriele Librandi, Katia Bertoldi Snap-through instability of shallow arches is a well-known phenomenon and it has been extensively investigated in the literature. However, the mechanics of shallow arches has not been exploited yet for engineering nonlinear mechanical metamaterials. In this study, we use shallow arches as building blocks for realizing snapping-through bistable nonlinear structures. |
Friday, March 8, 2019 9:24AM - 9:36AM |
X21.00006: X-ray creation by relativistic electrons in a nanophotonic vacuum Nicholas Rivera, Liang Jie Wong, John D Joannopoulos, Marin Soljacic, Ido Kaminer The vanishingly small response of matter to light beyond ultraviolet (UV) frequencies makes it challenging to leverage concepts from nanophotonics to manipulate the emission and propagation of light at such frequencies. Here, we show that free-electron based two-quanta processes allow tunable light sources from UV to gamma ray frequencies, without the need for any external electromagnetic fields. We find that the intentional design of vacuum fluctuations by tuning the permittivity of a material at IR frequencies allows one to exert direct control over the spectrum and intensity of output X-ray radiation. The per-electron power of such X-ray emission is comparable with that of synchrotrons employing a 0.1-1 T magnetic field. We find that this powerful emission derives its strength from the strong Casimir-Polder forces in the extreme nanoscale of materials. Fundamentally, our results reveal a way to apply the tools of nanophotonics even at frequencies where materials do not respond. They also constitute a new mechanism by which vacuum fluctuations can be used to generate high frequency light, potentially enabling new concepts such as compact and tunable sources of photons from UV-to-gamma-ray energies. |
Friday, March 8, 2019 9:36AM - 9:48AM |
X21.00007: Imaging collective behavior in an rf-SQUID metamaterial tuned by DC and RF magnetic fields Alexander P. Zhuravel, Seokjin Bae, Steven Anlage We examine the collective behavior of two-dimensional nonlinear superconducting metamaterials using a novel imaging technique. The metamaterial is made up of self-resonating microwave oscillators in a strongly coupled 27 x 27 planar array of radio-frequency Superconducting QUantum Interference Devices (rf SQUIDs). By using low-temperature laser scanning microscopy (LSM) we image the photoresponse caused by local heating across the SQUID array, and this corresponds to the strength of oscillation of each meta-atom. Complex collective modes of the metamaterial which are not revealed in global measurements become visible to the LSM. The clustering of active meta-atoms in each collective mode of the metamaterial are imaged. We observe the rearrangement of coherent patterns due to meta-atom resonant frequency tuning as a function of external dc and rf magnetic flux bias. We find that the excited rf SQUID distribution across the metamaterial at zero dc flux and small rf flux reveals a low degree of coherence. By contrast, the spatial coherence heals upon increasing of rf flux amplitude. We discuss possible origins of such coherence variations. |
Friday, March 8, 2019 9:48AM - 10:00AM |
X21.00008: Towards Room Temperature Plasmonic Lasing from Zn-Doped GaAs Nanowires Gyanan Aman, Fatemesadat Mohammadi, Mykhaylo Lysevych, Hoe Tan, Chennupati Jagadish, Heidrun Schmitzer, Martin Fraenzl, Marc Cahay, Hans Peter Wagner We investigated optically pumped lasing from zinc-doped GaAs nanowires (NWs) on a Au film and from NWs comprising a nominally 10 nm thick Au coating at temperatures ranging from 80 to 295 K. The NWs have an average diameter and length of 200 nm and 2.5 µm, respectively, and possess a 7 nm thin Al2O3 spacer layer surrounding the NWs. The NWs were optically excited with 150 fs laser pulses with a center wavelength of 770 nm which were provided by a Ti-Sapphire laser. Due to the shortness of the NWs only one longitudinal lasing mode resonates with the gain spectrum which extends from ~1.48 to 1.52 eV at 80 K. At higher temperature the lasing mode slightly shifts towards lower energy and weakens due to band-gap shrinkage and increasing non-radiative losses at surface states. The lasing output versus excitation power (L-L) plot at 80 and 295 K shows the characteristic “S” shape curve for NWs on Au. The L-L plot for Au coated NWs shows lasing at 80 K but suggests amplified spontaneous emission at 295 K due to higher plasmonic losses. A simulation of the experimental data with FDTD calculations reveals that lasing from NWs on Au is predominantly plasmonic while it has a hybrid photonic-plasmonic character in Au coated NWs. |
Friday, March 8, 2019 10:00AM - 10:12AM |
X21.00009: Characterization of a Single Quantum Meta-atom for a Superconducting Quantum Transmission Line Metamaterial Jingnan Cai, Steven Anlage The quantum transmission line (QTL) metamaterial provides a unique opportunity to investigate emergent quantum phenomena, due to the strong coupling between the meta-atoms and the bosonic mode in the resonator as well as the quantum mechanical nature of such interaction. Two designs for QTL are considered in this study: flux and charge qubits embedded in a coplanar waveguide, the latter of which possesses interesting nonlinear coupling between neighboring meta-atoms that depend on the quantum state of the Josephson junction. Here we report the first step towards the realization of QTL metamaterial: the design, fabrication, and characterization of a single flux qubit in the coplanar waveguide. The characterization, which will eventually include vacuum Rabi splitting, Rabi oscillations, and quantum tomography, will be conducted through a microwave transmission measurement. |
Friday, March 8, 2019 10:12AM - 10:24AM |
X21.00010: Programmable Multiplex Optical Bandpass Filter via Laser Reshaping of Gold Nanostructure Kyoungweon Park, Jake Fontana, Jason Streit, Jamie Gengler, Carl M Liebig, Richard Vaia Optical bandpass filters allow or reject a range of wavelengths. Metallic nanorods (NRs) and their assemblies are a promising platform for such components due to their intense light-matter interactions and ability to tune optical cross-section based on the NR's aspect ratio and volume. Fabrication of arbitrary NR filter design however is challenging due to synthetic limitations on aspect ratio and inherent polydispersity. Herein we demonstrate design and fabrication of arbitrary optical notch filters with a flat top profile using new synthetic strategies combined with wavelength selective particle resphaping. Bandwidth and spectral profile is defined by a collection of NRs with narrow longitudinal plasmon resonances (LSPR) that define absorption and sharp roll-off at the filter edges. Laser irradiation transcribes transmission notches by reshaping a population of NRs in resonance with the LSPR. Furthermore, single or multiple transmission windows across the visible to mid-IR can be fabricated using polydisperse NRs or nanowires. Experimental validation of fabrication models confirm rational design of position, depth, and width of the transmission window, enabling manufacturing of complex optical elements (solutions or solid) not found in natural media. |
Friday, March 8, 2019 10:24AM - 10:36AM |
X21.00011: Large-scale testing and simulation of nanofabricated thermionic energy converters Peter Scherpelz, Stephen E Clark, Arvind Kannan, Hsin-I Lu, Daniel Merthe Thermionic energy converters are a potential technology for efficient, direct, and compact heat-to-electricity conversion with no moving parts. We discuss the testing and simulation of devices for thermionic conversion which incorporate a nanofabricated electrostatic lensing system to mitigate space charge. In order to achieve high performance, these devices must minimize loss of the vacuum electrons to the electrostatic grids, which requires precise modeling of electron emission and absorption. We demonstrate the use of a large experimental dataset, encompassing a variety of grid geometries and operating conditions, to validate and improve our model. Specifically, we show that including effects such as dielectric charging provides statistically significant improvements in agreement between experiments and kinetic particle-in-cell simulations. We then use these models to improve device performance, exemplifying the value of experimental validation. |
Friday, March 8, 2019 10:36AM - 10:48AM |
X21.00012: ABSTRACT WITHDRAWN
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