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Georgia T Papadakis, Dagny Fleischman, Artur Davoyan, Pochi Yeh, Harry A Atwater
Harnessing artificial optical magnetism has previously required complex two- and three-dimensional structures, such as nanoparticle arrays and split-ring metamaterials. By contrast, planar structures, and in particular dielectric/metal multilayer metamaterials, have been generally considered non-magnetic. Although the hyperbolic and plasmonic properties of these systems have been extensively investigated, their assumed non-magnetic response limits their performance to transverse magnetic (TM) polarization. We propose and experimentally validate a mechanism for artificial magnetism in planar multilayer metamaterials...
January 18, 2018: Nature Communications
Lin Chen, Xianmin Ke, Huijie Guo, Junhao Li, Xun Li, Lei Zhou
Although metamaterials wave-plates have been demonstrated previously, many of them suffer from the issue of narrow bandwidth since they typically rely on resonance principles and thus exhibit inevitable frequency dispersions. Here, we show that the dispersion of spoof surface plasmon (SSP) mode supported by a fishbone structure can be freely modulated by varying the structural parameters. This motivates us to establish a general strategy of building broadband wave-plates by cascading two fishbone structures with different propagation constants of SSP modes...
January 18, 2018: Scientific Reports
Ying Li, Xue Bai, Tianzhi Yang, Hailu Luo, Cheng-Wei Qiu
Thermal camouflage has been successful in the conductive regime, where thermal metamaterials embedded in a conductive system can manipulate heat conduction inside the bulk. Most reported approaches are background-dependent and not applicable to radiative heat emitted from the surface of the system. A coating with engineered emissivity is one option for radiative camouflage, but only when the background has uniform temperature. Here, we propose a strategy for radiative camouflage of external objects on a given background using a structured thermal surface...
January 18, 2018: Nature Communications
Dean Culver, Yaroslav Urzhumov
Theory and practical implementations for wake-free propulsion systems are proposed and proven with computational fluid dynamic modeling. Introduced earlier, the concept of active hydrodynamic metamaterials is advanced by introducing magnetohydrodynamic metamaterials, structures with custom-designed volumetric distribution of Lorentz forces acting on a conducting fluid. Distributions of volume forces leading to wake-free, laminar flows are designed using multivariate optimization. Theoretical indications are presented that such flows can be sustained at arbitrarily high Reynolds numbers...
December 2017: Physical Review. E
Yu O Averkov, Yu V Prokopenko, V M Yakovenko
The interaction between a tubular beam of charged particles and a dispersive metamaterial of cylindrical configuration has been investigated theoretically. This metamaterial may have negative permittivity and negative permeability simultaneously over a certain frequency range where it behaves like a left-handed metamaterial. The dispersion equation for the eigenmodes spectra of a metamaterial and the coupled modes spectra of the system have been derived and numerically analyzed. It has been found that the absolute beam instability of bulk-surface waves occurs because of peculiarities of the eigenmodes spectra of a left-handed metamaterial...
July 2017: Physical Review. E
M J Mirzaali, S Janbaz, M Strano, L Vergani, A A Zadpoor
Architectured materials with rationally designed geometries could be used to create mechanical metamaterials with unprecedented or rare properties and functionalities. Here, we introduce "shape-matching" metamaterials where the geometry of cellular structures comprising auxetic and conventional unit cells is designed so as to achieve a pre-defined shape upon deformation. We used computational models to forward-map the space of planar shapes to the space of geometrical designs. The validity of the underlying computational models was first demonstrated by comparing their predictions with experimental observations on specimens fabricated with indirect additive manufacturing...
January 17, 2018: Scientific Reports
Ahmed Salim, Sungjoon Lim
Metamaterial elements/arrays exhibit a sensitive response to fluids yet with a small footprint, therefore, they have been an attractive choice to realize various sensing devices when integrated with microfluidic technology. Micro-channels made from inexpensive biocompatible materials avoid any contamination from environment and require only microliter-nanoliter sample for sensing. Simple design, easy fabrication process, light weight prototype, and instant measurements are advantages as compared to conventional (optical, electrochemical and biological) sensing systems...
January 15, 2018: Sensors
Haibin Zhang, Chunlin Guan, Ning Song, Yuanyuan Zhang, Hong Liu, Jingzhong Fang
Herein, we present an effective bottom-up strategy to fabricate unprecedented macroscopic two-dimensional (2D) plasmonic gold superlattices composed of high-index faceted gold nanocrystal building blocks (NBBs) at the air-liquid interface. In this approach, a synergistic electrostatic and layered self-assembly technique was executed using unique icosidodecahedral gold nanocrystals. It showed that centimeter-squared areas of close-packed monolayer films were formed, and the interparticle spacing of neighbouring Au NBBs could be facilely manipulated from hundreds to several nanometers...
January 16, 2018: Physical Chemistry Chemical Physics: PCCP
Kathryn H Matlack, Marc Serra-Garcia, Antonio Palermo, Sebastian D Huber, Chiara Daraio
Identifying material geometries that lead to metamaterials with desired functionalities presents a challenge for the field. Discrete, or reduced-order, models provide a concise description of complex phenomena, such as negative refraction, or topological surface states; therefore, the combination of geometric building blocks to replicate discrete models presenting the desired features represents a promising approach. However, there is no reliable way to solve such an inverse problem. Here, we introduce 'perturbative metamaterials', a class of metamaterials consisting of weakly interacting unit cells...
January 15, 2018: Nature Materials
Marc Serra-Garcia, Valerio Peri, Roman Süsstrunk, Osama R Bilal, Tom Larsen, Luis Guillermo Villanueva, Sebastian D Huber
The modern theory of charge polarization in solids is based on a generalization of Berry's phase. The possibility of the quantization of this phase arising from parallel transport in momentum space is essential to our understanding of systems with topological band structures. Although based on the concept of charge polarization, this same theory can also be used to characterize the Bloch bands of neutral bosonic systems such as photonic or phononic crystals. The theory of this quantized polarization has recently been extended from the dipole moment to higher multipole moments...
January 15, 2018: Nature
Artem Danilov, Gleb Tselikov, Fan Wu, Vasyl G Kravets, Igor Ozerov, Frederic Bedu, Alexander N Grigorenko, Andrei V Kabashin
When excited over a periodic metamaterial lattice of gold nanoparticles (~ 100nm), localized plasmon resonances (LPR) can be coupled by a diffraction wave propagating along the array plane, which leads to a drastic narrowing of plasmon resonance lineshapes (down to a few nm full-width-at-half-maximum) and the generation of singularities of phase of reflected light. These phenomena look very promising for the improvement of performance of plasmonic biosensors, but conditions of implementation of such diffractively coupled plasmonic resonances, also referred to as plasmonic surface lattice resonances (PSLR), are not always compatible with biosensing arrangement implying the placement of the nanoparticles between a glass substrate and a sample medium (air, water)...
December 9, 2017: Biosensors & Bioelectronics
Angelos Xomalis, Iosif Demirtzioglou, Eric Plum, Yongmin Jung, Venkatram Nalla, Cosimo Lacava, Kevin F MacDonald, Periklis Petropoulos, David J Richardson, Nikolay I Zheludev
Recently, coherent control of the optical response of thin films in standing waves has attracted considerable attention, ranging from applications in excitation-selective spectroscopy and nonlinear optics to all-optical image processing. Here, we show that integration of metamaterial and optical fibre technologies allows the use of coherently controlled absorption in a fully fiberized and packaged switching metadevice. With this metadevice, which controls light with light in a nanoscale plasmonic metamaterial film on an optical fibre tip, we provide proof-of-principle demonstrations of logical functions XOR, NOT and AND that are performed within a coherent fibre network at wavelengths between 1530 and 1565 nm...
January 12, 2018: Nature Communications
Qiangqiang Zhang, Feng Zhang, Xiang Xu, Chi Zhou, Dong Lin
It is a significant challenge to concurrently achieve scalable fabrication of graphene aerogels with three-dimensional (3D) tailorable architectures (e.g., lattice structure) and controllable manipulation of microstructures on the multiscale. Herein, we highlight 3D graphene lattices (GLs) with complex engineering architectures that were delicately designed and manufactured via 3D stereolithography printed hollow polymer template-mediated hydrothermal process coupled with freeze-drying strategies. The resulting GLs with overhang beams and columns show a 3D geometric configuration with hollow-carved features at the macroscale, while the construction elements of graphene cellular on the microscale exhibit a well-ordered and honeycomb-like microstructure with high porosity...
January 12, 2018: ACS Nano
Jianjia Yi, Sawyer D Campbell, Rui Feng, Shah Nawaz Burokur, Douglas H Werner
Complex electromagnetic structures can be designed by exploiting the concept of spatial coordinate transformations. In this paper, we define a coordinate transformation scheme that enables one to taper the electric field between two waveguides of different cross-sections. The electromagnetic field launched from the wide input waveguide is compressed in the proposed field tapering device and guided into the narrow output waveguide. In closed rectangular waveguide configurations, the taper can further play the role of a mode selector due to the output waveguide's cut-off frequency...
January 8, 2018: Optics Express
Jiří Čtyroký, Juan Gonzalo Wangüemert-Pérez, Pavel Kwiecien, Ivan Richter, Ján Litvik, Jens H Schmid, Íñigo Molina-Fernández, Alejandro Ortega-Moñux, Milan Dado, Pavel Cheben
Properties of reflection and transmission spectral filters based on Bragg gratings in subwavelength grating (SWG) metamaterial waveguides on silicon-on-insulator platform have been analyzed using proprietary 2D and 3D simulation tools based on Fourier modal method and the coupled-mode theory. We also demonstrate that the coupled Bloch mode theory can be advantageously applied to design of Bragg gratings in SWG waveguides. By combining different techniques, including judiciously positioning silicon loading segments within the evanescent field of the SWG waveguide and making use of its dispersion properties, it is possible to attain sub-nanometer spectral bandwidths for both reflection and transmission filters in the wavelength range of 1550 nm while keeping minimum structural features of the filters as large as 100 nm...
January 8, 2018: Optics Express
Feng Wang, Hayk Harutyunyan
Plasmonic nanoantennas and metamaterials concentrate optical energy into nanometric volumes strongly enhancing the light-matter interaction. This makes them promising platforms for optical sensing, nonlinear effects and quantum optics. However, absorption losses and radiative damping result in broad, low quality factor (Q) resonances of plasmonic systems that significantly limit their performance. Here, we develop a hybrid plasmonic/dielectric metasurface that can simultaneously achieve high Q and large field enhancement values in the near infrared by forming a hybridized mode between the nanoantennas' plasmonic mode and the photonic waveguide mode of Si device layer...
January 8, 2018: Optics Express
Rui Yang, Pei Yang, Yongchao Chen, Jiacheng Li, Zhenya Lei
We propose a sandwiched transparent epsilon-near-zero (ENZ) metamaterial screen to release the obliquely incident electromagnetic fields. More specifically, the transmission properties through ENZ metamaterials are investigated when incorporated with an interlayer of a meta-surface having periodic complementary spiral-resonator-matrixes. We show that both TE- and TM-polarized electromagnetic waves are capable of penetrating the ENZ metamaterials under a wide-angle range of illuminations, and the greatly enhanced transmissions are turning out to be frequency dispersionless for different polarized electromagnetic fields with different incident angles...
January 1, 2018: Optics Letters
Fangrong Hu, Yixing Fan, Xiaowen Zhang, Wenying Jiang, Yuanzhi Chen, Peng Li, Xianhua Yin, Wentao Zhang
We experimentally demonstrated a tunable terahertz bandpass filter based on microelectromechanical systems (MEMS) reconfigurable metamaterials. The unit cell of the filter consists of two split-ring resonators (SRRs) and a movable bar. Initially, the movable bar situates at the center of the unit cell, and the filter has two passbands whose central frequencies locate at 0.65 and 0.96 THz. The intensity of the two passbands can be actively modulated by the movable bar, and a maximum modulation depth of 96% is achieved at 0...
January 1, 2018: Optics Letters
Saraswati Behera, Swagato Sarkar, Joby Joseph
In this Letter we report for the first time, to the best of our knowledge, a phase spatial light modulator (SLM)-based interference lithography (IL) approach for the realization of hexagonally packed helical photonic structures with a submicrometer scale spatial, as well as axial, periodicity over a large area. A phase-only SLM is used to electronically generate six phase-controlled plane beams. These six beams from the front side and a direct central backside beam are used together in an "inverted umbrella" geometry setup to realize the desired submicrometer axial periodic chiral photonic structures through IL...
January 1, 2018: Optics Letters
Zhen Gao, Zhuoyuan Wang, Baile Zhang
It has been recently reported that the unit cell of wire media metamaterials can be tailored locally to shape the flow of electromagnetic waves at deep-subwavelength scales [Nat. Phys.9, 55 (2013)NPAHAX1745-247310.1038/nphys2480]. However, such bulk structures have a thickness of at least the order of wavelength, thus hindering their applications in the on-chip compact plasmonic integrated circuits. Here, based upon a Sievenpiper "mushroom" array [IEEE Trans. Microwave Theory Tech.47, 2059 (1999)IETMAB0018-948010...
January 1, 2018: Optics Letters
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