scholarly journals Invisible surfaces enabled by the coalescence of anti-reflection and wavefront controllability in ultrathin metasurfaces

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hongchen Chu ◽  
Haoyang Zhang ◽  
Yang Zhang ◽  
Ruwen Peng ◽  
Mu Wang ◽  
...  
Keyword(s):  
High Efficiency ◽  
Negative Refraction ◽  
Dielectric Surface ◽  
Great Flexibility ◽  
Reflection And Refraction ◽  
Arbitrary Phase ◽  
Incident Waves ◽  
Air Interfaces ◽  
Dielectric Objects ◽  
Simultaneous Elimination

AbstractReflection inherently occurs on the interfaces between different media. In order to perfectly manipulate waves on the interfaces, integration of antireflection function in metasurfaces is highly desired. In this work, we demonstrate an approach to realize exceptional metasurfaces that combine the two vital functionalities of antireflection and arbitrary phase manipulation in the deep subwavelength scale. Such ultrathin devices confer reflection-less transmission through impedance-mismatched interfaces with arbitrary wavefront shapes. Theoretically and experimentally, we demonstrate a three-layer antireflection metasurface that achieves an intriguing phenomenon: the simultaneous elimination of the reflection and refraction effects on a dielectric surface. Incident waves transmit straightly through the dielectric surface as if the surface turns invisible. We further demonstrate a wide variety of applications such as invisible curved surfaces, “cloaking” of dielectric objects, reflection-less negative refraction and flat axicons on dielectric-air interfaces, etc. The coalescence of antireflection and wavefront controllability in the deep subwavelength scale brings new opportunities for advanced interface optics with high efficiency and great flexibility.

Capture of 2-D Crack Growth Path by the Polygonal Numerical Manifold Method

2012 ◽  
Vol 166-169 ◽  
pp. 3224-3227
Author(s):  
Hui Hua Zhang
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
High Efficiency ◽  
Numerical Manifold Method ◽  
Growth Path ◽  
Great Flexibility ◽  
Materials Modeling ◽  
Polygonal Elements ◽  
Crack Growth Path ◽  
Numerical Manifold

Due to the independence of physical domain and the mathematical cover system, the numerical manifold method (NMM) can efficiently simulate crack propagation without remeshing. At the same time, the polygonal elements are also very attractive due to their great flexibility in meshing and high efficiency in materials modeling. In the present paper, the NMM is applied to solve 2-D crack propagation problems on polygonal elements. Our numerical results show that the proposed method can well capture the crack growth trajectory compared with the reference solution

Reconfigurable All Dielectric Metasurfaces based on Optical Phase Change Materials: Design Approaches

2020 ◽  
Vol 35 (11) ◽  
pp. 1445-1446
Author(s):  
Mikhail Shalaginov ◽  
Sensong An ◽  
Yifei Zhang ◽  
Fan Yang ◽  
Clayton Fowler ◽  
...  
Keyword(s):  
Phase Change ◽  
Light Propagation ◽  
Phase Change Materials ◽  
High Efficiency ◽  
Focal Length ◽  
Large Change ◽  
Optical Phase ◽  
Main Challenge ◽  
Arbitrary Phase ◽  
Large Tuning Range

Optical metasurface is a recently emerged paradigm for controlling light propagation, which enables implementation of ultra-compact optical devices with extended functionalities. Nowadays the main challenge in the field is to realize active metasurfaces with high quality, high efficiency, and large tuning range. Here we present a design approach for constructing a two-state reconfigurable metalens made of low-loss optical phase-change material (O-PCM). The metalens design is capable to produce diffraction limited focusing, large change in focal length (from 1.5 mm to 2mm), and decent focusing efficiency of about 20% in both states. The proposed design methodology is generic and can be easily extended towards constructing metasurfaces, which can switch between two or more arbitrary phase maps.

Reflection and refraction of SH waves in presence of slip and friction

1978 ◽  
Vol 68 (4) ◽  
pp. 999-1011
Author(s):  
Eugene L. Chez ◽  
J. Dundurs ◽  
Maria Comninou
Keyword(s):  
Elastic Waves ◽  
Mixed Boundary ◽  
Mechanical Energy ◽  
Applied Pressure ◽  
Mixed Boundary Conditions ◽  
Sliding Velocity ◽  
Sh Waves ◽  
Sliding Motion ◽  
Reflection And Refraction ◽  
Incident Waves

abstract The reflection of elastic waves is customarily treated by assuming that the interface neither separates nor slips. This paper considers the reflection of SH waves that are strong enough to break friction between two solids which are pressed together, so that localized slip takes place. It is also assumed that the solids are sheared, which enhances slip in one direction and leads to a global sliding motion. The problem might at first appear as forbidding because of the mixed boundary conditions and the inequalities involved. It is discovered, however, that it can be solved in closed form for angles of incidence that avoid total reflection. The global sliding velocity, the sizes of the slip zones, and the rate at which mechanical energy is dissipated are displayed in terms of the independent variables involving the amplitude of the incident waves, and the applied pressure and shearing tractions.

scholarly journals High-Efficiency Electromagnetic Wave Controlling with All-Dielectric Huygens’ Metasurfaces

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zheng-bin Wang ◽  
Jin Shi ◽  
Jin-chang Chen
Keyword(s):  
High Efficiency ◽  
Physical Mechanism ◽  
Three Dimensional ◽  
Building Blocks ◽  
Side Lobe ◽  
Antenna System ◽  
Low Loss ◽  
Full Wave ◽  
Low Profile ◽  
Incident Waves

Subwavelength dielectric blocks with varying thicknesses are introduced to realize 0∼2πphase change. A Huygens’ metasurface composed of such nonuniform building blocks is shown to efficiently refract normally incident waves in a broadband. According to the same physical mechanism, we fabricate an electrically thin lens with concentric subwavelength dielectric blocks and integrate it with a patch antenna to form a three-dimensional (3D) ultra-low-profile lens antenna system. Full-wave simulation demonstrates the lens antenna’s excellent performances in high directivity, broadband, low loss, and low side-lobe levels.

scholarly journals High-order multipoles in all-dielectric metagrating enabling ultralarge-angle light bending with unity efficiency

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tie-Jun Huang ◽  
Li-Zheng Yin ◽  
Jin Zhao ◽  
Pu-Kun Liu
Keyword(s):  
High Efficiency ◽  
Negative Refraction ◽  
Beam Steering ◽  
Large Angle ◽  
Transverse Magnetic ◽  
Electric Polarization ◽  
High Order ◽  
Optical Diffraction ◽  
Optical Wave ◽  
Low Efficiency

Abstract Gradient metasurfaces have been extensively applied in the unprecedented control of light beams over thin optical components. However, these metasurfaces suffer from low efficiency when bending light through large angles and high fabrication demand when it requires fine discretion. In this work, we investigate all-dielectric metagratings based on the generalized Kerker effect induced by interference between Mie-type resonances. It allows extraordinary optical diffraction for beam steering through ultralarge angles. The coupling inside and between the lattices in the metagrating can be used to tune the excited states of the electric and magnetic resonances, including both the fundamental dipoles and high-order multipoles, leading to an ideal asymmetrical scattering pattern that redistributes the energy between the diffraction channels as required. The quadrupole and hexadecapole not only significantly enhance the working efficiency but also enable distinctive possibilities for wave manipulation that cannot be reached by dipoles. Utilizing a thin array of silicon rods, large-angle negative refraction and reflection are realized with almost unity efficiency under both transverse magnetic and transverse electric polarization. Compared with conventional metasurfaces, such an all-dielectric metagrating has the merits of high flexibility, high efficiency, and low fabrication requirements. The coupling and interactions among the multipoles may serve as a foundation for various forms of on-chip optical wave control.

scholarly journals High-Efficiency Dual-Frequency Reflective Linear Polarization Converter Based on Metasurface for Microwave Bands

2019 ◽  
Vol 9 (9) ◽  
pp. 1910 ◽  
Author(s):  
Changfeng Fu ◽  
Zhijie Sun ◽  
Lianfu Han ◽  
Chao Liu ◽  
Tao Sun ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Dielectric Layer ◽  
High Efficiency ◽  
Conversion Ratio ◽  
Polarization Conversion ◽  
Dual Frequency ◽  
Polarization Converter ◽  
Polarization Control ◽  
Polarized Waves ◽  
Incident Waves

A dual-broadband and high-efficiency reflective linear polarization converter based on an anisotropic metasurface is presented. The device consists of two symmetrical, double-slotted metallic split-rings and one criss-cross structure, a dielectric layer, and a completely reflective metallic ground. The converter exhibits four resonances and can near-perfectly convert x- or y-polarized incident waves into cross-polarized waves in the frequency ranges of 9.38–13.36 GHz and 14.84–20.36 GHz. The polarization conversion ratios (PCRs) of the two bands are 98.21% and 99.32%, respectively. The energy conversion ratio (ECR) for energy loss measurement is almost 100% in these frequency bands. The polarization conversion principle is studied. The bandwidths and PCRs of the two bands are determined by varying the dielectric layer thickness. The simulation results are consistent with experimental observations. The designed dual-broadband and high-efficiency metasurface has great potential in the application of electromagnetic polarization control.

High Temperature Plasmonic Photonic Crystal MEMS Emitter

2009 ◽  
Vol 1162 ◽  
Author(s):  
Irina Puscasu ◽  
Edward Johnson ◽  
Andrew Taylor ◽  
Brent Schell ◽  
William Schaich ◽  
...  
Keyword(s):  
High Temperature ◽  
Photonic Crystal ◽  
High Speed ◽  
High Efficiency ◽  
Infrared Imaging ◽  
Dielectric Surface ◽  
Complex Frequency ◽  
Wafer Level ◽  
Sensing Applications ◽  
Spectral Control

AbstractWe describe a new class of plasmonic photonic crystal emitters integrated into a MEMS platform for high temperature-intensity, high speed, and high efficiency tuned emitting and sensing applications in the infrared. We exploit 2D organized metallo-dielectric surface structures for angular and spectral control of reflection, absorption and emission from surfaces in the infrared. We have built a FDTD model that incorporates complex frequency dependent properties and provides quantitative agreement with measured spectral data. High temperature materials and special fabrication techniques allow high temperature operation. This technology offers new solutions for spectral control with application in thermophotovoltaic (TPV) energy conversion. Built on a MEMS platform, for thermal isolation from the environment, these devices also modulate at high speed, opening new applications in spectroscopy, infrared imaging, and signaling. Demonstrated wafer-level vacuum sealing improves the wall plug efficiency dramatically. We describe device architecture and fabrication considerations for plasmonic photonic crystal structures which simultaneously act as emitters and sensors in a defined narrow waveband radiation. In particular, this combined capability opens new avenues for research for vital commercial applications such as environmental protection, household safety, bio-hazardous material identification, meteorology and industrial environments.

Propagation of p-, T-, and SV-waves at the interface between two solid–liquid media with magnetic field and initial stress in the context of two thermoelastic theories

2015 ◽  
Vol 93 (7) ◽  
pp. 807-823 ◽  
Author(s):  
S.M. Abo-Dahab
Keyword(s):  
Magnetic Field ◽  
Initial Stress ◽  
Tangential Force ◽  
Magnetic Field Effect ◽  
Tangential Displacement ◽  
Reflection And Refraction ◽  
Initial Area ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Incident Waves

In this paper, we study the effects of magnetic field and initial stress on p-, T-, and SV-waves propagation. We investigated the problem of reflection and refraction of thermoelastic waves at a magnetized solid–liquid interface in the presence of initial stress. In the context of classical theory and Green–Lindsay theory of thermoelasticity, the problem has been solved. The boundary conditions applied at the interface are: (i) displacement continuity; (ii) vanishing tangential displacement; (iii) continuity of normal force per unit initial area; (iv) tangential force per unit initial area must vanish; and (v) continuity of temperature. The amplitudes ratios for the incident p-, T-, and SV-waves have been obtained. The reflection and transmittion coefficients from the incident waves are computed numerically, considering the initial stress and magnetic field effect and the results obtained have been presented graphically.

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