Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session F01: Applications: Electromagnetic Radiation, Detectors and Antennae |
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Sponsoring Units: FIAP Chair: Dmitry Voronine, University of South Florida Room: LACC 150A |
Tuesday, March 6, 2018 11:15AM - 11:27AM |
F01.00001: Controlling the vertical transport of photocarriers to the surface E Laine Wong, Andrew Winchester, Michael Man, Vivek Pareek, Julien Madéo, Keshav Dani Spatial control of the vertical transport of carriers from the bulk to the surface for photochemical processes could provide improved selectivity and efficiency. Here we exploit the intensity variations in the photoexciting beam to drive competing nonlinear optical processes, and thereby allow vertical carrier tranport in only selected regions within the photoexcited spot. Using time-resolved photoemission microscopy, we make a movie of the resulting spatially inhomogeneous photocarrier dynamics. Our work provides a new pathway to control charge and current distributions in space and time within an optical spot, with implications for photovoltaics, photocatalysis and semiconductor devices. |
Tuesday, March 6, 2018 11:27AM - 11:39AM |
F01.00002: Air-Stable Room-Temperature Mid-Infrared Photodetectors Based on hBN/Black Arsenic Phosphorus/hBN Heterostructures Shaofan Yuan, Chenfei Shen, Bingchen Deng, Xiaolong Chen, Qiushi Guo, Yuqiang Ma, Ahmad Abbass, Bilu Liu, Ralf Haiges, Claudia Ott, Tom Nilges, Kenji Watanabe, Takashi Taniguchi, Ofer Sinai, Doron Naveh, Chongwu Zhou, Fengnian Xia Recently, layered black phosphorus (BP) has been explored intensively for infrared optoelectronic applications due to its high carrier mobility and the moderate direct bandgap (about 0.33 electron volt) in the thin film form. In this work, we demonstrate mid-infrared photodetectors based on black arsenic phosphorus (b-AsxP1-x), whose bandgap can be below 0.15 electron volt by the introduction of arsenic. Mid-infrared photodetectors have been demonstrated leveraging the hexagonal boron nitride (hBN)/b-As0.83P0.17/hBN heterostructures. The encapsulation of hBN prevents b-As0.83P0.17 from oxidization and eliminates surface trap states, therefore the as-fabricated photodetectors work in intrinsic photoconductive mode, and show peak room-temperature extrinsic responsivity of 320, 24.7, and 1.03 mA/W at 3.4, 5.0, and 7.7 μm, respectively. The broadband and high-speed detection at mid-infrared illustrates the potential of b-As0.83P0.17 for optoelectronic applications, such as thermal imaging, biomedical sensing, and free-space mid-infrared communications. |
Tuesday, March 6, 2018 11:39AM - 11:51AM |
F01.00003: Surface Plasmon Polariton Modified Exciton De-excitation in Quantum Dot Qiang Gao, xiaoguang li, Zhenyu Zhang We report theoretically a full quantum mechanical study for a prototypical system composed of a spherical quantum dot (QD) close to a metal surface. Due to the excitation of surface plasmon polaritons (SPPs), the strong electromagnetic fields near the metal surface are expected to modify the de-excitation rate of the quantum dot. Through the development of a new theoretical model with quantized SPP, we find that the de-excitation rate of the exciton in quantum dots can be modified by controlling both the crystal orientation and size of the QD. Most importantly, the quantization of the SPP enables us to find that although the radiative de-excitation of the spherical quantum dot should satisfy the quantum selection rule of the angular momentum, a new selection-rule forbidden de-excitation channel is open up due to the SPP and exciton coupling. The quantum interference between the new and the conventional selection-rule allowed channels can dramatically modify the total de-excitation rate of the exciton. Our theoretical predictions of technological importance can be readily tested experimentally, and are expected to guide new strategies to advance the quantum-dot-based applications by combining the QD and systems supporting SPPs. |
Tuesday, March 6, 2018 11:51AM - 12:03PM |
F01.00004: Polarization-dependent electromagnetic responses of ultrathin and highly flexible asymmetric terahertz metasurfaces Joshua Burrow, Riad Yahiaoui, Andrew Sarangan, Imad Agha, Jay Mathews, Thomas Searles We report the polarization-dependent electromagnetic response from a series of novel terahertz (THz) metasurfaces where asymmetry is introduced through the displacement of two adjacent metallic arms separated by a distance δ. For all polarization states, the symmetric metasurface exhibits a low quality (Q) factor fundamental dipole mode. By breaking the symmetry, we experimentally observe a secondary dipole-like mode with a Q factor nearly 9x higher than the fundamental resonance. As δ increases, the fundamental dipole mode f1 redshifts and the secondary mode f2 blueshifts creating a highly transmissive spectral window. Polarization-dependent measurements reveal a full suppression of f2 for all asymmetries at θ ≥ 60°. Furthermore, at δ ≥ 60 μm, we observe a polarization selective electromagnetic induced transparency (EIT) for the fundamental mode. This work paves the way for applications in filtering, sensing and slow-light devices common to other high Q factor THz metasurfaces with EIT-like response. |
Tuesday, March 6, 2018 12:03PM - 12:15PM |
F01.00005: Capturing Light: 3D solid mappings of near field intensity produced by plasmonic antennas Michael Naughton, Michael Burns, Juan Merlo Optical antennas (OAs) have found a place in modern technology due to their special properties including, among others, high concentration of electromagnetic fields in their proximity [1]. Analysis of the radiation patterns (RPs) generated by OAs is necessary to determine their possible applications. Until now, studies of such patterns have been made by fluorescent dyes or near field techniques, with inherent disadvantages of each technique, i.e. photobleaching and time consuming experiments [2]. Here, we show a methodological study of the three-dimensional radiation pattern produced by OAs, polymerized on SU8. This technique allows us to determine the geometrical characteristics of the RP without using perturbative probes that can eventually modify the main properties of such a RP. Comparison with numeric calculations implemented by FEM showed good agreement with the experimental results, demonstrating the feasibility of our approach. |
Tuesday, March 6, 2018 12:15PM - 12:27PM |
F01.00006: Optimal Near Fields in Pyramid-Shaped Nanostructures Zachary Withers, Dmitry Voronine Optimal near field distributions in pyramid-shaped nanostructures are obtained through manipulations of electromagnetic radiation using an analytic optimization algorithm based on near field interference and polarization laser pulse shaping. The nanostructure near field responses to changes in polarization, incidence angle, and wavelength are analyzed to optimize the results. Potential nano-optical devices, including the focusing of sub-wavelength images, depending on the dynamic control of the interaction between the radiation and the nanostructures are discussed. |
Tuesday, March 6, 2018 12:27PM - 12:39PM |
F01.00007: Active Tuning with Photochromic Molecules Coupled to Plasmonic Nanoantennas Wade Wilson, Jon Stewart, Maiken Mikkelsen Plasmonic nanostructures with actively tunable resonances promise to enable smart materials with multiple functionalities, on-chip spectral-based imaging and dynamically reconfigurable optoelectronic devices. A variety of tunable materials have been integrated with plasmonic structures, however, the tuning range in the visible regime has been limited to less than the linewidth of the resonance resulting in small on/off ratios. Here we demonstrate dynamic, reversible tuning of plasmon resonances up to 71 nm in the visible regime by incorporating photochromic molecules into plasmonic nanopatch antennas. Ultraviolet light is used to switch between two isomers with different refractive indices demonstrating a tuning figure of merit of 1.43, defined as the ratio between the tuning range and the linewidth of the resonance. Moreover, the effect of the dispersion on the tuning range is elucidated by studying over 40 individual nanoantennas with fundamental resonances from 550 to 720 nm, revealing good agreement with finite-element simulations. |
Tuesday, March 6, 2018 12:39PM - 12:51PM |
F01.00008: Gate-Tunable Photomemory Effect in MoS2 Transistors Andreij Gadelha, Alisson Cadore, Kenji Watanabe, Takashi Taniguchi, Ana de Paula, Leandro Malard, Rodrigo Gribel Lacerda, Leonardo Campos We report a photomemory effect with the record of on/off ratio and retention time in MoS2 transistors. The photomemory is controlled by gate voltage application, exhibiting multilevel states. Further, a memory state is recorded mainly on the laser spot area, demonstrating strong potential for photomemory miniaturization. The photomemory effect presented here is based on a photodoping effect. In such a way, the combined actions of laser exposure and application of gate potentials set large densities of charges in MoS2 channel. Such outstanding modification of MoS2 conductance allows definition of the binary memory states. In this way, our work opens possibilities for novel memory architectures. |
Tuesday, March 6, 2018 12:51PM - 1:03PM |
F01.00009: Electrical Potentials Introduced by Electron-Beam during in situ Cyclic Voltammagrams in a Commercial Electrochemical Liquid Cell Transmission Electron Microscope Holder Todd Brintlinger, Nabraj Bhattarai
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Tuesday, March 6, 2018 1:03PM - 1:15PM |
F01.00010: Multimode Microwave Sensors for Cell and Microdroplet Analysis in Microfluidics Hande Aydogmus, Levent Aslanbas, Mehmet Kelleci, Selcuk Erbil, Mehmet Hanay Simultaneous use of multiple modes of a resonant sensor can provide spatial information about analytes. In the context of micro and nano-mechanical sensors, multimode measurements provide size and shape information as well as the mass of the analyte. By combining the spatial information obtained in the measurements, an image can be reconstructed [1]. This technique, Inertial Imaging, transforms the capabilities of nanomechanical sensors to a new level: the combined knowledge of molecular mass, size and shape of the analyte can enable previously unattainable information for biomolecular analytics. These principles, originally developed for mechanical sensors, can be extended to electromagnetic resonant sensing as well[2]. By embedding microfluidic channels between the signal line and ground plane of a microstripline resonator, the excess electrical volume and position of microdoplets and HeLa cells have been measured. Sensing with higher order modes in this platform can yield further spatial properties of analytes. |
Tuesday, March 6, 2018 1:15PM - 1:27PM |
F01.00011: Toroidal Response of Asymmetric Metasurfaces with Multiple High Q-Factor Resonances Sirak Mekonen, Riad Yahiaoui, Joshua Burrow, Andrew Sarangan, Imad Agha, Jay Mathews, Thomas Searles Recently, toroidal resonance-based metamaterials (MMs) have been used to demonstrate fascinating THz applications including, but not limited to, electromagnetically induced transparency (EIT), optical filters, bio-chemical sensing, etc. Here, we report numberical simulations and experimental investigations of an array of split ring resonators (SRRs) deposited periodically on the top side of high-resistivity silicon substrate. The investigated SRRs exhibits a toroidal dipolar resonance at around 1.6 THz for TM-polarization and 1.5 THz for TE-polarization. Numerical simulations were performed using a finite element method (FEM) based software to analyze the electromagnetic responses of the proposed metasurfaces. In addition, by breaking the symmetry of the resonators, we achieved a high Q-factor ~ 43. We employed a high-speed asynchronous sampling terahertz spectroscopy system (HASSP-THz) to experimentally study the toroidal geometry. We present electric, magnetic and surface current of each high Q factor Fano resonance within the 0.8-2.4 frequency range. |
Tuesday, March 6, 2018 1:27PM - 1:39PM |
F01.00012: 3D display prototype enabled by a new Fresnel hologram algorithm Denizhan Kesim, Ghaith Makey, Ozgun Yavuz, Ahmet Turnali, Serim Ilday, Onur Tokel, Fatih Ilday The tunable absorption/emission profiles of quantum dots combined with local excitation due to two photon absorption provides many exciting opportunities for applications such as displays. Here, we present a 3D holographic display prototype exploiting a novel holographic approach by exciting a quantum dot solution at multiple planes simultaneously. We developed a computer generated hologram algorithm [2] which can generate a single Fresnel hologram, capable of projecting multi-plane images. The resulting 3D image is of high-quality and low cross-talk. The algorithm utilizes both iterative Fourier transform algorithms and Fresnel holography in a combined strategy. In experiments, we used a femtosecond fiber laser to excite the solution which have absorption/emission peaks around 400/610 nm. We used the algorithm to optically reconstruct 6 well-separated points in 3D to create a helix with dimensions of 3 x 3 x 15 mm. This approach is promising for dynamic 3D displays with high frame rate and contrast. Results are scalable to real-time calculation, provide full focal control and are achieved with a single spatial light modulator. |
Tuesday, March 6, 2018 1:39PM - 1:51PM |
F01.00013: Metasurface-based MEMS THz-to-IR focal plane array1 Leroy Pimental, Fabio Alves, Gamani Karunasiri Terahertz (THz) technology has gained momentum in recent years owing to special properties of THz waves of being non-ionizing and at the same time being able to penetrate through nonmetallic and non-polar materials. Nearly perfect THz absorption, optimized to particular THz quantum cascade laser (QCL) illumination sources, was achieved using metal-dielectric metasurfaces. The metasurfaces are comprised of ultra-thin films of silicon oxide and aluminum, deposited on silicon substrates and were fabricated using standard MEMS processes. The metasurface absorbers were structurally integrated onto an array of thermally insulated free-standing MEMS membranes that work as heat accumulators. The temperature of array is probed directly by a commercial thermal camera, translating the THz scene to infrared. The main characteristics such as spectral response, thermal time constant and sensitivity are controlled by the geometry and tuned by design according to the application demands. The results indicate a great potential of using these THz sensors in real-time imaging applications. |
Tuesday, March 6, 2018 1:51PM - 2:03PM |
F01.00014: Optical Properties of Anisotropic Gold Nanoframes Moha Shahjamali, Negin Zaraee, Nicolas Large In recent years, a lot of effort has been made to design and create anisotropic plasmonic nanostructures including metallic bowtie and anisotropic ring or frame nanostructures to achieve plasmonic hotspots in particular for enhanced-spectroscopies and sensing applications. Among all, triangular gold nanoframes (TGNFs) are of high interest due to their optical anisotropy, tunable dimensions, and also their strong, high coverage plasmonic fields resulting from the coupling between the external and internal plasmon modes. Here we show that using TGNFs has four-fold advantage in comparison to triangular silver nanoprism (TSNP): 1) A nanoframe has 70% less material than nanoprism but generates up to seven-fold increase in the total electric field enhancement. 2) TGNFs are much more stable than TSNP due to chemical inertness of gold. 3) TGNFs have no surfactant/organic molecule which allows for an increased reactivity and LSPR intensity. 4) TGNFs are more sensitive both for LSPR sensing and Surface-Enhanced Raman Scattering (SERS) applications. The results from TGNFs will guide us to design other frame-based structures with various shape and compositions to generate high electric field enhancement. |
Tuesday, March 6, 2018 2:03PM - 2:15PM |
F01.00015: Far Field Wireless Power Transfer to Biomedical Implants using Metamaterial Amit Baghel, Sisir Nayak In this article, the far field wireless power transfer (WPT) for charging biomedical implants using metamaterial is proposed. The 3D-model of the voxel human body is taken in the CST Microwave Studio environment and the study is carried out. To power the biomedical implants in the far field region, the voxel is placed at the distance of 723 mm (≥ 2D2/λ = 721 mm, where D is the maximum dimension of the antenna and λ = 122.45 mm) from the aperture of the horn-antenna. The input power to the antenna is maintained to 0.5 W according to the federal communication commission (FCC) rules. Without the metamaterial (MM), the power density in W/m2 at the skin, skeleton muscles, bones are 2.97, 2.95 and 2.9 W/m2 respectively. With the MM, the respective values are 3.46, 3.44 and 3.38 W/m2. The WPT with MM in biomedical implants can be implemented taking into consideration the average and maximum permissible SAR value for the human exposure. Improvement of 17% in the received power with MM as compared to without MM is seen, thus giving more power to the implants. The MM array also helps in beam shaping and try to confine the area of microwave, thus exposing fewer tissues to the waves. Improvement in the rectenna can help in harvesting more power from the source |
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