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Markus Smith, Sidney T Malak, Jaehan Jung, Young Jun Yoon, Chun Hao Lin, Sunghan Kim, Kyung Min Lee, Ruilong Ma, Timothy J White, Timothy J Bunning, Zhiqun Lin, Vladimir V Tsukruk
This work demonstrates a facile and versatile method for generating low scattering crosslinked quantum dots (QD)-polymer composite films and patterned highly emissive structures with ultra-high QD loading, minimal phase-separation, and tunable mechanical properties. Uniform QD-polymer films are fabricated using thiol-ene chemistry, in which cross-linked polymer networks are rapidly produced in ambient conditions via fast UV polymerization in bulk to suppress QD aggregation. UV-controlled thiol-ene chemistry limits phase separation through producing highly QD loaded crosslinked composites with loading rate above majority of those reported in literature (<1%) and approaching 30%...
April 25, 2017: ACS Applied Materials & Interfaces
Andrew Barrick, Amélie Châtel, Mélanie Bruneau, Catherine Mouneyrac
The field of environmental toxicology developed as a result of growing concerns about anthropogenic influences on the environment and how to ameliorate ecological impact. Many governmental bodies are beginning to emphasize prevention rather than mitigation when addressing novel products, leading to more of a focus on identifying potential toxicity prior to release. With the exponential advances in their development and sale, novel metamaterials and biotechnology are set to dramatically outpace the capabilities of current testing strategies...
April 25, 2017: Environmental Toxicology and Chemistry
Chuanbing Cheng, Runhua Fan, Yanrong Ren, Tao Ding, Lei Qian, Jiang Guo, Xiaofeng Li, Liqiong An, Yanhua Lei, Yansheng Yin, Zhanhu Guo
While metal is the most common conductive constituent element in the preparation of metamaterials, one-dimensional conductive carbon nanotubes (CNTs) provide alternative building blocks. Here alumina (Al2O3) nanocomposites with multi-walled carbon nanotubes (MWCNTs) uniformly dispersed in the alumina matrix were prepared by hot-pressing sintering. As the MWCNT content increased, the formed conductive MWCNT networks led to the occurrence of the percolation phenomenon and a change of the conductive mechanism...
April 25, 2017: Nanoscale
Jitendra K Pradhan, S Anantha Ramakrishna, Bharathi Rajeswaran, Arun M Umarji, Venu Gopal Achanta, Amit K Agarwal, Amitava Ghosh
A metamaterial consisting of an array of gold micro-disks, separated from a ground plane of indium tin oxide (ITO) by a thin film of vanadium dioxide (VO<sub>2</sub>), behaves as a perfect absorber at infrared (IR) frequencies at room temperature. This metamaterial, which is transparent to visible light, can be switched to a highly reflecting state for IR light by heating the metamaterial to temperatures larger than the metal-insulator phase transition temperature 68°C of VO<sub>2</sub>...
April 17, 2017: Optics Express
Andriy Shevchenko, Markus Nyman, Ville Kivijärvi, Matti Kaivola
Spatial dispersion is an intriguing property of essentially all nanostructured optical media. In particular, it makes optical waves with equal frequencies and polarizations have different wavelengths, if they propagate in different directions. This can offer new approaches to control light radiation and propagation. Spatially dispersive nanomaterials, such as metamaterials, are often treated in terms of wave parameters, such as refractive index and impedance retrieved from reflection and transmission coefficients of the material at each incidence angle...
April 17, 2017: Optics Express
Zi-Xun Jia, Yong Shuai, Yan-Ming Guo, He-Ping Tan
In this paper, a double layer nanoparticle-crystal has been proposed, which shown incident and polarization angle, substrate independences for spectral absorptivity. Such phenomenon originates from the near-field light redistribution and excitation of internal collective oscillating. This kind of nanoparticle-crystal can be made of various types of metal with similar optical responses. A three oscillators mode has been proposed in this paper to understand the shift between global and internal collective oscillating, and verify the physical picture demonstrated...
April 17, 2017: Optics Express
Stefano Stassi, Alessandro Chiadò, Giuseppe Calafiore, Gianluca Palmara, Stefano Cabrini, Carlo Ricciardi
Fano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering (SERS). Despite such interest in nano-optics, no experimental evidence of Fano interference was reported up to now for purely nanomechanical resonators, even if classical mechanical analogies were referred from a theoretical point of view...
April 21, 2017: Scientific Reports
Lorenzo M Procopio, Lee A Rozema, Zi Jing Wong, Deny R Hamel, Kevin O'Brien, Xiang Zhang, Borivoje Dakić, Philip Walther
In standard quantum mechanics, complex numbers are used to describe the wavefunction. Although this has so far proven sufficient to predict experimental results, there is no theoretical reason to choose them over real numbers or generalizations of complex numbers, that is, hyper-complex numbers. Experiments performed to date have proven that real numbers are insufficient, but the need for hyper-complex numbers remains an open question. Here we experimentally probe hyper-complex quantum theories, studying one of their deviations from complex quantum theory: the non-commutativity of phases...
April 21, 2017: Nature Communications
Debabrata Sikdar, Alwin Bucher, Cristian Zagar, Alexei A Kornyshev
Self-assembling arrays of metallic nanoparticles at liquid|liquid or liquid|solid interfaces could deliver new platforms for tuneable optical systems. Such systems can switch between very-high and very-low reflectance states upon assembly and disassembly of nanoparticles at the interface, respectively. This encourages creation of electro-variably reversible mirror/window nanoplasmonic devices. However, the response time of these systems is usually limited by the rate-of-diffusion of the nanoparticles in the liquid, towards the interface and back...
April 21, 2017: Faraday Discussions
Katherine Bourzac
No abstract text is available yet for this article.
April 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
Pengwei Wang, Naibo Chen, Chaojun Tang, Jing Chen, Fanxin Liu, Saiqian Sheng, Bo Yan, Chenghua Sui
We theoretically studied how to directly engineer the constitutive parameters of metamaterials for perfect absorbers of electromagnetic waves. As an example, we numerically investigated the necessary refractive index n and extinction coefficient k and the relative permittivity ε and permeability μ of a metamaterial anti-reflection layer, which could cancel the reflection from a hydrogenated amorphous silicon (α-Si:H) thin film on a metal substrate, within the visible wavelength range from 300 to 800 nm...
December 2017: Nanoscale Research Letters
Osama R Bilal, André Foehr, Chiara Daraio
The realization of acoustic devices analogous to electronic systems, like diodes, transistors, and logic elements, suggests the potential use of elastic vibrations (i.e., phonons) in information processing, for example, in advanced computational systems, smart actuators, and programmable materials. Previous experimental realizations of acoustic diodes and mechanical switches have used nonlinearities to break transmission symmetry. However, existing solutions require operation at different frequencies or involve signal conversion in the electronic or optical domains...
April 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
Yannan Shen, P G Kevrekidis, G P Veldes, D J Frantzeskakis, D DiMarzio, X Lan, V Radisic
In the present work, we explore soliton and roguelike wave solutions in the transmission line analog of a nonlinear left-handed metamaterial. The nonlinearity is expressed through a voltage-dependent, symmetric capacitance motivated by recently developed ferroelectric barium strontium titanate thin-film capacitor designs. We develop both the corresponding nonlinear dynamical lattice and its reduction via a multiple scales expansion to a nonlinear Schrödinger (NLS) model for the envelope of a given carrier wave...
March 2017: Physical Review. E
Guoshuai Zhen, Peiheng Zhou, Xiaojia Luo, Jianliang Xie, Longjiang Deng
Surface plasmon polaritons (SPPs) and standing wave modes provide interesting and exotic properties for infrared metamaterial absorbers. Coupling of these modes promises further development in this field but restricted by the complexity of modes analysis. In this work, we investigate the general phenomenon of modes coupling supported by a metal (with grating)-dielectric-metal sandwich structure based on rigorous coupled-wave analysis (RCWA) method and experiment results. Through the analysis of fundamental modes, a new approach based on the boundary conditions is introduced to reveal the coupling mechanism and the corresponding resonance shifting phenomenon with simple but rigorous derivations...
April 11, 2017: Scientific Reports
Tongyu Ding, Jianjia Yi, Haoyu Li, Hailin Zhang, Shah Nawaz Burokur
A novel three-dimensional (3D) optical lens structure for electromagnetic field shaping based on spatial light transformation method is proposed at microwave frequencies. The lens is capable of transforming cylindrical wavefronts into planar ones, and generating a directive emission. Such manipulation is simulated and analysed by solving Laplace's equation, and the deformation of the medium during the transformation is theoretically described in detail. The two-dimensional (2D) design method producing quasi-isotropic parameters is further extended to a potential 3D realization with all-dielectric gradient refractive index metamaterials...
April 10, 2017: Scientific Reports
Arum Jung, Changho Kim, Bongjun Yeom
Chiral nanomaterials are characterized by handedness morphology on the nanoscale, manifested as preferential interaction with circularly polarized light. However, the origin of this light-matter interaction remains elusive. Here we simulated a model of chiral helical arrays of plasmonic nanoparticles with central anisotropic nanopillars to examine the effect of birefringence on the collective chiroptical response. Contrary to typical assumptions in previous works, we varied the biaxial refractive indices of the central nanopillars and observed a significant modulation of optical activity by calculating and characterizing circular dichroism (CD) spectra...
April 20, 2017: Journal of Physical Chemistry Letters
Soroush Kamrava, Davood Mousanezhad, Hamid Ebrahimi, Ranajay Ghosh, Ashkan Vaziri
We present a novel cellular metamaterial constructed from Origami building blocks based on Miura-ori fold. The proposed cellular metamaterial exhibits unusual properties some of which stemming from the inherent properties of its Origami building blocks, and others manifesting due to its unique geometrical construction and architecture. These properties include foldability with two fully-folded configurations, auxeticity (i.e., negative Poisson's ratio), bistability, and self-locking of Origami building blocks to construct load-bearing cellular metamaterials...
April 7, 2017: Scientific Reports
A Libál, C Nisoli, C Reichhardt, C J Olson Reichhardt
We demonstrate the use of an external field to stabilize and control defect lines connecting topological monopoles in spin ice. For definiteness we perform Brownian dynamics simulations with realistic units mimicking experimentally realized artificial colloidal spin ice systems, and show how defect lines can grow, shrink or move under the action of direct and alternating fields. Asymmetric alternating biasing forces can cause the defect line to ratchet in either direction, making it possible to precisely position the line at a desired location...
April 5, 2017: Scientific Reports
In-Sung Lee, Ik-Bu Sohn, Chul Kang, Chul-Sik Kee, Jin-Kyu Yang, Joong Wook Lee
We report on a method for realizing high refractive index metamaterials using corrugated metallic slot structures at terahertz frequencies. The effective refractive index and peak index frequency can be controlled by varying the width of the air gap in the corrugated slot arrays. The phenomenon occurs because of the secondary resonance effect due to the fundamental inductive-capacitive resonance, which generates a red-shift of the fundamental resonance determined by twice the length of the corrugated metallic slots...
March 20, 2017: Optics Express
Dmitry V Guzatov, Vasily V Klimov, Hsun-Chi Chan, Guang-Yu Guo
We have obtained analytical expressions for the radiative decay rate of the spontaneous emission of a chiral molecule located near a dielectric spherical particle with a chiral nonconcentric spherical shell made of a bi-isotropic material. Our numerical and graphical analyses show that material composition, thickness and degree of non-concentricity of the shell can influence significantly the spontaneous radiation of the chiral molecule. In particular, the radiative decay rates can differ in orders of magnitude for a chiral molecule located near the thin and thick parts of a nonconcentric shell as well as near a concentric shell made of chiral metamaterial...
March 20, 2017: Optics Express
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