Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session A62: Nanostructures and Metamaterials IFocus
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Sponsoring Units: DMP Chair: Natalia Litchinitser, Duke University Room: Mile High Ballroom 4C |
Monday, March 2, 2020 8:00AM - 8:36AM |
A62.00001: Flying Micro-Lightsails: Optical Levitation and Propulsion of Nanostructured Ultralight Macroscopic Objects Invited Speaker: Harry Atwater The Breakthrough Starshot Initiative initiated in 2016 defined an audacious goal of sending a spacecraft beyond to a neighboring star, Proxima Centauri within the next half-century. Its vision for an ultralight spacecraft that can be accelerated by laser radiation pressure from an Earth-based source to ~20% of the speed of light demands the use of materials with extreme properties. Here we examine stringent criteria for the lightsail materials design, thermal management and dynamical stability, and discuss lightsail design and first experimental steps by exploration of small (<1 mm2) microscale lightsails. We explore nanophotonic design of materials, thermal management, and self-stabilizing optical manipulation, levitation and propulsion of lightweight macroscopic (i.e., mm, cm, or even meter-scale) micro-lightsails via radiation pressure. We consider the materials characteristics required to realize robust, thermally stable building blocks, and find that stable trajectories for dynamic motion of macro-objects can be achieved by controlling the anisotropy of light scattering along the object surface. With radiative cooling being the sole mechanism for passive thermal management in vacuum or space, we quantify the stringent requirements on material absorptivity that enable these structures to withstand high laser intensities and prevent excessive heating and mechanical failure. Achievement of stable optical manipulation and propulsion of macroscale (i.e., >> wavelength in size) structures, via radiation pressure appears to be possible by the use of structured optical beams and tailored nanophotonic design. Reaching this goal requires the conception and design of new ultralight photonic structures composed of materials with extreme optical, mechanical and thermal properties. |
Monday, March 2, 2020 8:36AM - 8:48AM |
A62.00002: Fundamental Limits on Electromagnetic Scattering in Nanostructured Materials: Upper Bounds on Extinction, Purcell Enhancement, and Absorption Pengning Chao, Sean Molesky, Prashanth S Venkataram, Weiliang Jin, Alejandro Rodriguez Advances in computational optimization (inverse design) and experimental fabrication techniques suggest the possibility of approaching the fundamental limits of optical control, which remain largely unknown. Through algebraic analysis of the scattering properties of Maxwell's equations, we formulate new constraints on various optical scattering processes, such as extinction and absorption, and apply these to establish upper bounds on thermal emission, radiative heat transfer, and Purcell enhancement in nanostructured materials. These bounds are general and useful in that they apply to arbitrary structures while incorporating the most relevant aspects of any photonic design problem: the material a given structure will be made of and the volume it will occupy. In particular, the bounds demonstrate the degree to which large metallic response and nanostructuring can be exploited to enhance light-matter interactions, with applications to single-photon extraction, photovoltaics, LEDs, and Raman scattering. They also reveal a transition from quasistatic (subwavelength) to ray optics behavior, and are shown to be nearly tight by comparison with structures discovered through inverse design. |
Monday, March 2, 2020 8:48AM - 9:00AM |
A62.00003: Hot-Electron Generation and Photothermal Effect in Plasmonic Nanostructures and Metamaterials Alexandre Govorov, Lucas Vazquez Besteiro Generation of energetic (hot) electrons and photo-heating are intrinsic properties of any plasmonic nanocrystal under illumination [1,2]. While the photo-heating effect is well described classically, the generation of hot electrons (HEs) is a quantum process and its theoretical description requires advanced quantum approaches [2]. The energy efficiency of such hot-electron processes is always limited. However, there are interesting possibilities to achieve the hot-electron enhancement [1]. The generation of high-energy HEs is a key mechanism for several applications such as plasmonic photodetectors, photocatalysis and ultrafast spectroscopy [1,2]. In particular, photochemistry induced by HEs and heating represent a very active area, which also involves chiral metamaterials and chiral photocatalysis [3]. |
Monday, March 2, 2020 9:00AM - 9:36AM |
A62.00004: Optical and Thermal Metamaterials for Scalable Applications Invited Speaker: Xiaobo Yin Micro/nano-structured materials offer significantly new opportunities for high efficiency devices and systems for energy harvesting, conversion and storage. Fundamental understanding at the small scale enables us to design structures and materials with unprecedented performances. However, there is a tremendous gap between the proof-of-principle demonstration at small scale and the intrinsically large scale real-world thermal and energy systems. In this talk, I will give an overview on our research and, more specifically, present our recent metamaterial development for emerging food, energy and water applications. |
Monday, March 2, 2020 9:36AM - 9:48AM |
A62.00005: Self-Cleaning and Tunable Structural Color Generation by TiO2/Ti nanostructures Gaurav Shukla, Angappane Subramanian Structural colors are known for its long term sustainability in comparison to dyes, pigments, etc., but generating self-cleaning structural colors by nano/micro structuring is quite challenging. Here, we report self-cleaning structural color generation by TiO2 nanorods and thin films on Ti sputtered glass and polyethylene terephthalate (PET) substrates deploying glancing angle deposition (GLAD) method. Reflected colors are tuned by varying height of TiO2 nanorods or thin film on Ti films. Both the front and back surface of the samples show different colors, called Janus optical effect, due to altered dielectric constant on both sides of Ti film. All as-deposited TiO2 nanorods and thin film samples are hydrophobic and hydrophilic respectively while both is transformed to reversible superhydrophilic state, a self-cleaning state, by UV irradiation. Further, annealing of samples on glass substrates has made the samples semi-transparent or transparent having superhydrophilic surface. Besides, structural colors are demonstrated for information encryption and optical ethanol sensing. Nevertheless, these structural colored specimens are promising for immense applications in the field of color printing, smart windows etc. |
Monday, March 2, 2020 9:48AM - 10:00AM |
A62.00006: Two-dimensional nanostructed materials for catalytic activities: a combined experimental and theoretical study Tekalign Terfa Debela, Hong Seok Kang Two-dimensional (2D) MoS2 nanostructures have attracted much attention in recent years because of their excellent electrocatalytic activity toward the hydrogen evolution reaction (HER). Herein, we report unique 2D hybrid nanostructures of MoS2 and melamine synthesized via a one-step solvothermal process.[1] The hybrid complexes with 7% intercalated melamine exhibited excellent HER Performance, with a current of 10 mA cmâ2 at 0.136 V (vs. RHE) and a Tafel slope of 37 mV decâ1. Our first-principles calculations showed that the intercalation of hydrogen-bonded melamine clusters could stabilize the 1Tâ² phase MoS2 via substantial charge transfer. In addition, I will discuss our results on the selective reduction of CO2 to formic acid using indium-zinc bimetallic nanocrystals.[2] |
Monday, March 2, 2020 10:00AM - 10:12AM |
A62.00007: Nanostructured gold thermocouple for photodetection Mahdiyeh Abbasi, Charlotte Evans, Longji Cui, Xifan Wang, Douglas Natelson The Seebeck coefficient of a metal depends on the energy-dependent electrical conductivity, which in turn depends on the energy-dependent electron mean free path and the material band structure. At the nanoscale, when the geometric size is comparable with the mean free path of the electrons, single metal thermocouples can be fabricated by changing the material geometry across the thermocouple. By using plasmonically-resonant structures, different device geometries and sizes can be used for wavelength sensitive light detection. We will present experimental data and simulations of single metal gold nanostructures with different geometries that are plasmonically active with IR laser illumination. We will discuss how these devices can be used for photodetection and discuss future applications for these measurements. |
Monday, March 2, 2020 10:12AM - 10:24AM |
A62.00008: Tunable Hybrid Metal-Nitride Metamaterial Framework towards Plasmonic Sensing Xuejing Wang, Jie Jian, Susana Diaz Amaya, Cindy E. Kumah, Ping Lu, Jijie Huang, Lia Stanciu, Deirdre M. O'Carroll, Alexandra Boltasseva, Xinghang Zhang, Haiyan Wang
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Monday, March 2, 2020 10:24AM - 10:36AM |
A62.00009: Plasmon-Based Gas Detection with Graphene Ribbons Kaveh Khaliji, Sudipta Romen Biswas, Hai Hu, Xiaoxia Yang, Qing Dai, Sang-Hyun Oh, Phaedon Avouris, Tony Low Gas detection has impact across a wide range of disciplines with established markets in variety of industries, including healthcare, security, environmental, semiconductor, etc. Motivated by the recent experiments, which exploit plasmons in graphene to identify gas molecules, here, we inspect a prototype setup, where an array of graphene ribbons enables plasmon-based gas detection via trapping the molecules atop graphene surface. We explore the main trapping mechanisms in the setup, and discuss how these allow for plasmon-based detection with enhanced sensitivity. |
Monday, March 2, 2020 10:36AM - 10:48AM |
A62.00010: Three-dimensional printing of piezoelectric materials with designed anisotropy and their applications in underwater transducers Huachen Cui, Ryan Hensleigh, Desheng Yao, Dominic LoPinto, Xiaoyu Zheng We describe design and manufacturing routes to previously inaccessible classes of piezoelectric materials that have arbitrary piezoelectric coefficient tensors. Our scheme is based on the manipulation of electric displacement maps from families of structural cell patterns. We implement our designs by additively manufacturing free-form, perovskite-based piezoelectric nanocomposites with complex three-dimensional architectures. The resulting voltage response of the activated piezoelectric metamaterials at a given mode can be selectively suppressed, reversed or enhanced with applied stress. To demonstrate our novel design method and fabrication capability, we designed and fabricated underwater transducers consisting of rationally designed metamaterials to accommodate diverse situations, in which the piezoelectric composites convert mechanical vibrations into electrical voltages and vice versa. Through tuning geometry of the micro-architectures, resonance frequencies of these transducers can vary from 100Hz to 10MHz while the impedance is close to water. Moreover, we showed the feasibility and applicability of these transducers for the purpose of source detection, liquid quality monitoring, and directional sensing. |
Monday, March 2, 2020 10:48AM - 11:00AM |
A62.00011: 3D printable multi-directional piezoelectric sensor Desheng Yao, Huachen Cui, Ryan Hensleigh, Xiaoyu Zheng The electromechanical coupling behaviors of the piezoelectric materials enable their wide applications in sensing systems. However, the comprehensive measurement of the stress tensor presented significant challenges for current piezoelectric sensing devices. Notably, the evaluation of the surface shear stress requires complicated structural designs along with intricate fabrication processes. Herein, we present the design methodology and manufacturing route to simultaneously extracting all individual components of the stress tensor. Our scheme is based on manipulating the deformation mechanism of each individual ligament within the piezoelectric micro-lattice structures. We implement our design principle via three-dimensional printing of free-form, piezo-active feedstock with high-resolution micro-architectures. The presented piezoelectric multi-mode sensor owns the capability of isolating the target stress components when subjecting to multiple external inputs. Innovated by these findings, the applicability of the multi-mode sensors is demonstrated by embedding them to the gas-solid interface as the conformal, flexible airflow sensor that is able to monitor the status of the airflow, as well as a self-sensing fluid pipe for liquid velocity field mapping. |
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