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https://www.readbyqxmd.com/read/28742059/spanning-the-scales-of-mechanical-metamaterials-using-time-domain-simulations-in-transformed-crystals-graphene-flakes-and-structured-soils
#1
Ronald Aznavourian, Tania Michelle Guenneau-Puvirajesinghe, Stephane Brule, Stefan Enoch, Sebastien Roger Guenneau
We begin with a brief historical survey of discoveries of quasi-crystals and graphene, and then introduce the concept of transformation crystallography, which consists of the application of geometric transforms to periodic structures. We consider motifs with three-fold, four-fold and six-fold symmetries according to the crystallographic restriction theorem. Furthermore, we define motifs with five-fold symmetry such as quasi-crystals generated by a cut-and-projection method from periodic structures in higher-dimensional space...
July 25, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28733654/direct-observation-of-topological-surface-state-arcs-in-photonic-metamaterials
#2
Biao Yang, Qinghua Guo, Ben Tremain, Lauren E Barr, Wenlong Gao, Hongchao Liu, Benjamin Béri, Yuanjiang Xiang, Dianyuan Fan, Alastair P Hibbins, Shuang Zhang
The discovery of topological phases has introduced new perspectives and platforms for various interesting physics originally investigated in quantum contexts and then, on an equal footing, in classic wave systems. As a characteristic feature, nontrivial Fermi arcs, connecting between topologically distinct Fermi surfaces, play vital roles in the classification of Dirac and Weyl semimetals, and have been observed in quantum materials very recently. However, in classical systems, no direct experimental observation of Fermi arcs in momentum space has been reported so far...
July 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28729669/active-ktao3-hybrid-terahertz-metamaterial
#3
Liang Wu, Jinglong Liu, Hui Li, Chunfeng Ding, Ningning Xu, Xiaolei Zhao, Zongcheng Xu, Quan Sheng, Jianquan Yao, Jining Li, Xin Ding, Weili Zhang
The dielectric properties of an active KTaO3 hybrid metamaterial structure and its tunability under external electric fields are investigated at room temperature by means of terahertz time-domain spectroscopy. Application of the electric field leads to an appreciable tuning of the dielectric loss, which is up to 17%. Meanwhile, the refractive index also changes appreciably. These findings are attributed to the internal space charge field in the crystal caused by the excited free carriers.
July 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28729629/assembly-of-3d-plasmonic-clusters-by-2d-afm-nanomanipulation-of-highly-uniform-and-smooth-gold-nanospheres
#4
Kyung Jin Park, Ji-Hyeok Huh, Dae-Woong Jung, Jin-Sung Park, Gwan H Choi, Gaehang Lee, Pil J Yoo, Hong-Gyu Park, Gi-Ra Yi, Seungwoo Lee
Atomic force microscopy (AFM) nanomanipulation has been viewed as a deterministic method for the assembly of plasmonic metamolecules because it enables unprecedented engineering of clusters with exquisite control over particle number and geometry. Nevertheless, the dimensionality of plasmonic metamolecules via AFM nanomanipulation is limited to 2D, so as to restrict the design space of available artificial electromagnetisms. Here, we show that "2D" nanomanipulation of the AFM tip can be used to assemble "3D" plasmonic metamolecules in a versatile and deterministic way by dribbling highly spherical and smooth gold nanospheres (NSs) on a nanohole template rather than on a flat surface...
July 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28723144/inflection-point-of-the-localized-surface-plasmon-resonance-peak-a-general-method-to-improve-the-sensitivity
#5
Peng Chen, Nhung Thi Tran, Xinglin Wen, Qihua Xiong, Bo Liedberg
The shift of the localized surface plasmon resonance (LSPR) spectrum is widely used in bio- and chemical sensing. Traditionally, the shift is monitored at the peak maximum of the extinction spectrum. We demonstrate that the inflection point at the long wavelength side of the peak maximum shows better refractive index sensitivity than the peak maximum. A consistent improvement in bulk refractive index sensitivity of 18-55% is observed for six different nanoparticles such as spherical particles of different sizes, nanostar and nanorods with different aspect ratios...
February 24, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28720892/dual-band-wide-angle-metamaterial-perfect-absorber-based-on-the-combination-of-localized-surface-plasmon-resonance-and-helmholtz-resonance
#6
Changlei Zhang, Cheng Huang, Mingbo Pu, Jiakun Song, Zeyu Zhao, Xiaoyu Wu, Xiangang Luo
In this article, a dual-band wide-angle metamaterial perfect absorber is proposed to achieve absorption at the wavelength where laser radar operates. It is composed of gold ring array and a Helmholtz resonance cavity spaced by a Si dielectric layer. Numerical simulation results reveal that the designed absorber displays two absorption peaks at the target wavelength of 10.6 μm and 1.064 μm with the large frequency ratio and near-unity absorptivity under the normal incidence. The wide-angle absorbing property and the polarization-insensitive feature are also demonstrated...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28720879/microwave-tunable-metamaterial-based-on-semiconductor-to-metal-phase-transition
#7
Guanqiao Zhang, He Ma, Chuwen Lan, Rui Gao, Ji Zhou
A microwave tunable metamaterial utilizing the semiconductor-to-metal transition of vanadium dioxide (VO2) is proposed, experimentally demonstrated and theoretically scrutinized. Basic concept of the design involves the combination of temperature-dependent hysteresis in VO2 with resonance induced heating, resulting in a nonlinear response to power input. A lithographically prepared gold split-rings resonator (SRR) array deposited with VO2 thin film is fabricated. Transmission spectra analysis shows a clear manifestation of nonlinearity, involving power-dependence of resonant frequency as well as transmitted intensity at both elevated and room temperature...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28719573/crystalline-metamaterials-for-topological-properties-at-subwavelength-scales
#8
Simon Yves, Romain Fleury, Thomas Berthelot, Mathias Fink, Fabrice Lemoult, Geoffroy Lerosey
The exciting discovery of topological condensed matter systems has lately triggered a search for their photonic analogues, motivated by the possibility of robust backscattering-immune light transport. However, topological photonic phases have so far only been observed in photonic crystals and waveguide arrays, which are inherently physically wavelength scaled, hindering their application in compact subwavelength systems. In this letter, we tackle this problem by patterning the deep subwavelength resonant elements of metamaterials onto specific lattices, and create crystalline metamaterials that can develop complex nonlocal properties due to multiple scattering, despite their very subwavelength spatial scale that usually implies to disregard their structure...
July 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/28710494/near-infrared-surface-enhanced-raman-scattering-based-on-star-shaped-gold-silver-nanoparticles-and-hyperbolic-metamaterial
#9
Chih-Hsien Lai, Guo-An Wang, Tsung-Kai Ling, Tzyy-Jiann Wang, Po-Kai Chiu, Yuan-Fong Chou Chau, Chih-Ching Huang, Hai-Pang Chiang
It is desirable to extend the surface-enhanced Raman scattering (SERS) from the conventionally used visible range into the infrared region, because the fluorescence background is lower in the long-wavelength regime. To do this, it is important to have a SERS substrate suitable for infrared operation. In this work, we report the near infrared SERS operation based on the substrates employing star-shaped gold/silver nanoparticles and hyperbolic metamaterial (HMM) structure. We first fabricate the SERS substrate in which nanoparticles are separated from a silver film by a thin dielectric layer...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28710432/electro-mechanical-light-modulator-based-on-controlling-the-interaction-of-light-with-a-metasurface
#10
Pablo Cencillo-Abad, Jun-Yu Ou, Eric Plum, Nikolay I Zheludev
We demonstrate a reflective light modulator, a dynamic Salisbury screen where modulation of light is achieved by moving a thin metamaterial absorber to control its interaction with the standing wave formed by the incident wave and its reflection on a mirror. Electrostatic actuation of the plasmonic metamaterial absorber's position leads to a dynamic change of the Salisbury screen's spectral response and 50% modulation of the reflected light intensity in the near infrared part of the spectrum. The proposed approach can also be used with other metasurfaces to control the changes they impose on the polarization, intensity, phase, spectrum and directional distribution of reflected light...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28710374/metadiffusers-deep-subwavelength-sound-diffusers
#11
Noé Jiménez, Trevor J Cox, Vicent Romero-García, Jean-Philippe Groby
We present deep-subwavelength diffusing surfaces based on acoustic metamaterials, namely metadiffusers. These sound diffusers are rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Strong dispersion is produced in the slits and slow sound conditions are induced. Thus, the effective thickness of the panel is lengthened introducing its quarter wavelength resonance in the deep-subwavelength regime. By tuning the geometry of the metamaterial, the reflection coefficient of the panel can be tailored to obtain either a custom reflection phase, moderate or even perfect absorption...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28708553/dispersion-differences-and-consistency-of-artificial-periodic-structures
#12
Z B Cheng, W K Lin, Z F Shi
Dispersion differences and consistency of artificial periodic structures, including phononic crystals, elastic metamaterials as well as periodic structures composited of phononic crystals and elastic metamaterials, are investigated in this paper. By developing a K(ω) method, complex dispersion relations and group/phase velocity curves of both the single mechanism periodic structures and the mixing mechanism periodic structures are calculated at first, from which dispersion differences of artificial periodic structures are discussed...
July 11, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28706290/dramatically-enhanced-spin-dynamo-with-plasmonic-diabolo-cavity
#13
Peng Gou, Jie Qian, Fuchun Xi, Yuexin Zou, Jun Cao, Haochi Yu, Ziyi Zhao, Le Yang, Jie Xu, Hengliang Wang, Lijian Zhang, Zhenghua An
The applications of spin dynamos, which could potentially power complex nanoscopic devices, have so far been limited owing to their extremely low energy conversion efficiencies. Here, we present a unique plasmonic diabolo cavity (PDC) that dramatically improves the spin rectification signal (enhancement of more than three orders of magnitude) under microwave excitation; further, it enables an energy conversion efficiency of up to ~0.69 mV/mW, compared with ~0.27 μV/mW without a PDC. This remarkable improvement arises from the simultaneous enhancement of the microwave electric field (~13-fold) and the magnetic field (~195-fold), which cooperate in the spin precession process generates photovoltage (PV) efficiently under ferromagnetic resonance (FMR) conditions...
July 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28702573/liter-scale-production-of-uniform-gas-bubbles-via-parallelization-of-flow-focusing-generators
#14
Heon-Ho Jeong, Sagar Yadavali, David Issadore, Daeyeon Lee
Microscale gas bubbles have demonstrated enormous utility as versatile templates for the synthesis of functional materials in medicine, ultra-lightweight materials and acoustic metamaterials. In many of these applications, high uniformity of the size of the gas bubbles is critical to achieve the desired properties and functionality. While microfluidics have been used with success to create gas bubbles that have a uniformity not achievable using conventional methods, the inherently low volumetric flow rate of microfluidics has limited its use in most applications...
July 25, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28699634/scalable-variable-index-elasto-optic-metamaterials-for-macroscopic-optical-components-and-devices
#15
Dongheok Shin, Junhyun Kim, Changwook Kim, Kyuyoung Bae, Seunghwa Baek, Gumin Kang, Yaroslav Urzhumov, David R Smith, Kyoungsik Kim
Optical metamaterials with an artificial subwavelength structure offer new approaches to implement advanced optical devices. However, some of the biggest challenges associated with the development of metamaterials in the visible spectrum are the high costs and slow production speeds of the nanofabrication processes. Here, we demonstrate a macroscale (>35 mm) transformation-optics wave bender (293 mm(2)) and Luneburg lens (855 mm(2)) in the broadband white-light visible wavelength range using the concept of elasto-optic metamaterials that combines optics and solid mechanics...
July 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28696764/achieving-arbitrary-control-over-pairs-of-polarization-states-using-complex-birefringent-metamaterials
#16
Alexander Cerjan, Shanhui Fan
We demonstrate that the key to realizing arbitrary control over pairs of polarization states of light, i.e., transforming an arbitrarily polarized pair of input states to an arbitrarily polarized pair of output states, is the ability to generate pairs of states with orthogonal polarizations from nonorthogonal pairs of initial states. Then, we develop a new class of non-Hermitian metamaterials, termed complex birefringent metamaterials, which are able to do exactly this. Such materials could facilitate the detection of small polarization changes in scattering experiments as well as enable new polarization multiplexing schemes in communications networks...
June 23, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28692279/hot-electron-intraband-luminescence-from-gaas-nanospheres-mediated-by-magnetic-dipole-resonances
#17
Jin Xiang, Shuai Jiang, Jingdong Chen, Jinxiang Li, Qiaofeng Dai, Chengyun Zhang, Yi Xu, Shaolong Tie, Sheng Lan
Significantly enhanced electric field in plasmonic hot spots can dramatically increase the linear and nonlinear absorption of light, leading to a high-temperature electron gas which radiates, through mainly intraband transition, a broadband luminescence quite similar to blackbody radiation. Here, we demonstrate that such hot-electron intraband luminescence (HEIL) can also be achieved by exploiting the significantly enhanced electric field at the magnetic dipole resonances of gallium arsenide (GaAs) nanospheres (NSs)...
July 12, 2017: Nano Letters
https://www.readbyqxmd.com/read/28690416/non-reciprocal-wave-propagation-in-modulated-elastic-metamaterials
#18
H Nassar, H Chen, A N Norris, M R Haberman, G L Huang
Time-reversal symmetry for elastic wave propagation breaks down in a resonant mass-in-mass lattice whose inner-stiffness is weakly modulated in space and in time in a wave-like fashion. Specifically, one-way wave transmission, conversion and amplification as well as unidirectional wave blocking are demonstrated analytically through an asymptotic analysis based on coupled mode theory and numerically thanks to a series of simulations in harmonic and transient regimes. High-amplitude modulations are then explored in the homogenization limit where a non-standard effective mass operator is recovered and shown to take negative values over unusually large frequency bands...
June 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28690408/wave-reflection-and-transmission-in-multiply-stented-blood-vessels
#19
T K Papathanasiou, A B Movchan, D Bigoni
Closed circulatory systems display an exquisite balance between vascular elasticity and viscous fluid effects, to induce pulse-smoothing and avoid resonance during the cardiac cycle. Stents in the arterial tree alter this balance through stiffening and because a periodic structure is introduced, capable of interacting with the fluid in a complex way. While the former feature has been investigated, the latter received no attention so far. But periodic structures are the building blocks of metamaterials, known for their 'non-natural' behaviour...
June 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28687811/electronically-switchable-broadband-metamaterial-absorber
#20
Dongju Lee, Heijun Jeong, Sungjoon Lim
In this study, the novel electronically switchable broadband metamaterial absorber, using a PIN diode, is proposed. The unit cell of the absorber was designed with a Jerusalem-cross resonator and an additive ring structure, based on the FR-4 dielectric substrate. Chip resistors and PIN diodes were used to provide both a broadband characteristic and a switching capability. To satisfy the polarization insensitivity, the unit cell was designed as a symmetrical structure, including the DC bias network, electronic devices, and conductor patterns...
July 7, 2017: Scientific Reports
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