scholarly journals Features of reflection of electromagnetic waves from nanometric perforated multilayers including epsilon-near-zero metamaterials

2019 ◽  
Vol 6 ◽  
pp. 22 ◽  
Author(s):  
Evgenii Starodubtsev
Keyword(s):  
Electromagnetic Waves ◽  
Phase Change Materials ◽  
Extreme Values ◽  
Exciting Radiation ◽  
Substrate Material ◽  
Boundary Problems ◽  
Reflected Waves ◽  
Main Layer ◽  
System Parameters ◽  
Epsilon Near Zero

Using the exact solutions of electromagnetic boundary problems, analytical modeling of reflection of electromagnetic waves from nanometric perforated multilayers has been carried out. New features of operation of the multilayers including the substrate or layers of epsilon-near-zero (ENZ) materials are established. Presence of the ENZ main layer or substrate leads to the quickly changing and extreme values of phase and module of amplitude reflection coefficients depending on the system parameters. The ENZ (or metallic for the thicker systems) substrate has a significant impact on the transformation of phase difference of the reflected waves. The detailed numerical analysis of the obtained results for the multilayers including silver or phase change materials (germanium antimony tellurium alloy, vanadium dioxide) components is performed. The considered reflection characteristics are reasonably “stable” to variation of the system parameters such as oblique incidence of the exciting radiation (for TE or TM polarization), possible presence of magnetic properties of the layers and effective electromagnetic anisotropy of the substrate material. The obtained results can be used to develop ultra-thin (with significantly subwavelength thicknesses) transformers of phase and amplitude of reflected radiation, holograms, metasurfaces and other nanophotonics applications.

scholarly journals Features of transmission of electromagnetic waves through composite nanoresonators including epsilon-near-zero metamaterials

2020 ◽  
Vol 7 ◽  
pp. 1 ◽  
Author(s):  
Evgenii Starodubtsev
Keyword(s):  
Electromagnetic Waves ◽  
Composite Layer ◽  
Exciting Radiation ◽  
Analytical Models ◽  
Main Layer ◽  
System Parameters ◽  
Transmission Coefficients ◽  
Transmitted Waves ◽  
Drastic Increase ◽  
Epsilon Near Zero

Transmission of electromagnetic waves through nanometric multilayers (nanoresonators) including a main composite layer made of two alternating strips of low-absorbing dielectrics that is sandwiched between epsilon-near-zero (ENZ) or metallic spacer layers has been modeled. Analytical models are based on exact solutions of electromagnetic boundary problems. The spacers with the definite properties lead to extreme dependences of amplitude transmission coefficients on the system parameters and drastic increase in phase difference of the transmitted waves. These effects are most pronounced for subwavelength multilayer thicknesses due to multibeam interference features in the nanoresonator, and they can be amplified when the main layer and (or) the whole system thicknesses decrease. The investigated transmission features take place under variations of the system parameters such as anisotropy of the main layer materials, non-ideal realization of ENZ materials, oblique incidence of the exciting radiation (for small incidence angles). The obtained results can have applications in development of ultra-thin nanophotonics devices using phase transformation of transmitted waves.

scholarly journals Homogenization of plasmonic crystals: seeking the epsilon-near-zero effect

2019 ◽  
Vol 475 (2230) ◽  
pp. 20190220 ◽  
Author(s):  
M. Maier ◽  
M. Mattheakis ◽  
E. Kaxiras ◽  
M. Luskin ◽  
D. Margetis
Keyword(s):  
Electromagnetic Waves ◽  
Bloch Wave ◽  
Design Problems ◽  
2D Material ◽  
Plasmonic Crystals ◽  
Optical Responses ◽  
Zero Effect ◽  
Vector Valued ◽  
Epsilon Near Zero

By using an asymptotic analysis and numerical simulations, we derive and investigate a system of homogenized Maxwell's equations for conducting material sheets that are periodically arranged and embedded in a heterogeneous and anisotropic dielectric host. This structure is motivated by the need to design plasmonic crystals that enable the propagation of electromagnetic waves with no phase delay (epsilon-near-zero effect). Our microscopic model incorporates the surface conductivity of the two-dimensional (2D) material of each sheet and a corresponding line charge density through a line conductivity along possible edges of the sheets. Our analysis generalizes averaging principles inherent in previous Bloch-wave approaches. We investigate physical implications of our findings. In particular, we emphasize the role of the vector-valued corrector field, which expresses microscopic modes of surface waves on the 2D material. We demonstrate how our homogenization procedure may set the foundation for computational investigations of: effective optical responses of reasonably general geometries, and complicated design problems in the plasmonics of 2D materials.

scholarly journals Improvement of Microwave Absorbance of Polymer Composites of W-Type Hexaferrite Powders by Attachment of Frequency Selective Surface

2017 ◽  
Vol 62 (2) ◽  
pp. 1325-1328
Author(s):  
H.-S. Cho ◽  
S.-S. Kim
Keyword(s):  
Reflection Loss ◽  
Electromagnetic Waves ◽  
Polymer Matrix Composites ◽  
Magnetic Loss ◽  
Frequency Selective Surface ◽  
Substrate Material ◽  
Matrix Composites ◽  
Frequency Selective ◽  
Ferrite Composites ◽  
Minimum Reflection Loss

AbstractThis work investigates the effect of a frequency selective surface (FSS) composed of a regular array of square loop elements on the absorption properties of grounded ferrite composites. Polymer matrix composites of CoZnW hexaferrite powders having small magnetic loss were used as the substrate material. Computational tools were used to model the interaction between electromagnetic waves and materials and determine the reflection coefficient. Reflection loss and bandwidth were greatly improved by attaching an FSS with controlled electrical resistance (R) onto the grounded ferrite composites. For the FSS withR= 800 Ω, the minimum reflection loss decreased to −25 dB at 10 GHz and the bandwidth was broadened to 7.5-12.5 GHz with respect to −10 dB reflection loss.

scholarly journals THERMAL CONDITIONING USING PHASE CHANGE MATERIALS

2003 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Boucíguez ◽  
L. T. Villa ◽  
M. A. Lara
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Computational Simulation ◽  
Practical Importance ◽  
Special Device ◽  
Boundary Problems ◽  
Chemical Systems ◽  
Monotone Dependence ◽  
Change Material ◽  
Moving Front

A combined procedure using a classical qualitative result for initial and boundary problems associated to parabolic equations, numerical treatment and computational simulation, have been used to obtain some results on the dynamic behavior of the function that provides the position of the melting interface or moving front of the phase change material at each time. This material is used in a special device that is designed in order to get thermal conditioning in physical - chemical systems of practical importance. A monotone dependence of the melting interface upon some parameters is also shown.

scholarly journals Design of hybrid narrow-band plasmonic absorber based on chalcogenide phase change material in the infrared spectrum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Israel Alves Oliveira ◽  
Igor Leonardo Gomes de Souza ◽  
Vitaly Felix Rodriguez-Esquerre
Keyword(s):  
Phase Change ◽  
Electromagnetic Waves ◽  
Phase Change Materials ◽  
Empirical Relation ◽  
Three Dimensional ◽  
Normal Incidence ◽  
Resonant Absorption ◽  
Nanophotonic Devices ◽  
Intermediate Phases ◽  
Infrared Spectral

AbstractStructures absorbing electromagnetic waves in the infrared spectral region are important optical components in key areas such as biosensors, infrared images, thermal emitters, and special attention is required for reconfigurable devices. We propose a three-dimensional metal-dielectric plasmonic absorber with a layer of PCM’s (Phase Change Materials). The phase shift effects of PCMs are numerically analyzed, and it is possible to obtain a shifting control of the resonant absorption peaks between the amorphous and crystalline states using the Lorentz–Lorenz relation. By using this empirical relation, we analyzed the peak absorption shift at intermediate phases between the amorphous and the crystalline. The geometric parameters of the structure with the PCM layer in the semi-crystalline state were adjusted to exhibit strong absorption for normal incidence. The effects of the oblique incidence on the absorption for the TM and TE polarization modes were also analyzed. Our results demonstrate that PCMs have great potential for reconfigurable nanophotonic devices.

scholarly journals Power flow–conformal metamirrors for engineering wave reflections

2019 ◽  
Vol 5 (2) ◽  
pp. eaau7288 ◽  
Author(s):  
Ana Díaz-Rubio ◽  
Junfei Li ◽  
Chen Shen ◽  
Steven A. Cummer ◽  
Sergei A. Tretyakov
Keyword(s):  
Power Distribution ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Flow Distribution ◽  
Physical Nature ◽  
Wave Reflections ◽  
Reflected Waves ◽  
Anomalous Reflection ◽  
Unit Cells ◽  
Reflecting Surfaces

Recently, the complexity behind manipulations of reflected fields by metasurfaces has been addressed, showing that, even in the simplest scenarios, nonlocal response and excitation of auxiliary evanescent fields are required for perfect field control. In this work, we introduce purely local reflective metasurfaces for arbitrary manipulations of the power distribution of reflected waves without excitation of any auxiliary evanescent field. The method is based on the analysis of the power flow distribution and the adaptation of the reflector shape to the desired distribution of incident and reflected fields. As a result, we find that these power-conformal metamirrors can be easily implemented with conventional passive unit cells. The results can be used for the design of reflecting surfaces with multiple functionalities and for waves of different physical nature. In this work, we present the cases of anomalous reflection and beam splitting for both acoustic and electromagnetic waves.

The effect of boundaries on wave propagation in a liquid-filled porous solid: III. Reflection of plane waves at a free plane boundary (general case)

1962 ◽  
Vol 52 (3) ◽  
pp. 595-625 ◽  
Author(s):  
H. Deresiewicz ◽  
J. T. Rice
Keyword(s):  
Electromagnetic Waves ◽  
Plane Waves ◽  
Body Waves ◽  
Porous Solid ◽  
Plane Boundary ◽  
Field Equations ◽  
Attenuation Coefficients ◽  
Reflected Waves ◽  
Three Body ◽  
Analytical Expressions

abstract A general solution is derived of Biot's field equations governing small motions of a porous solid saturated with a viscous liquid. The solution is then employed to study some of the phenomena attendant upon the reflection from a plane, traction-free boundary of each of the three body waves predicted by the equations. The problem, though more complex, bears some similarity to that of electromagnetic waves in a conducting medium, in that some of the reflected waves are inhomogeneous, planes of constant amplitude not coinciding with planes of constant phase. Analytical expressions are displayed for the phase velocities, attenuation coefficients, angles of reflection and the amplitude ratios, and explicit formulas are given for the limiting cases of low and high frequencies, representing first-order corrections for porosity of the solid and viscosity of the liquid, respectively. The paper concludes with a presentation of results of numerical calculations pertinent to a kerosene-saturated sandstone.

scholarly journals Multiphysics simulations of adaptive metasurfaces at the meta-atom length scale

Nanophotonics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 675-681 ◽  
Author(s):  
Sebastian Meyer ◽  
Zhi Yang Tan ◽  
Dmitry N. Chigrin
Keyword(s):  
Phase Transition ◽  
Electromagnetic Waves ◽  
Phase Change Materials ◽  
Length Scale ◽  
Perfect Absorber ◽  
Local Tuning ◽  
Self Consistent ◽  
Deposited Energy ◽  
Phase Amplitude ◽  
Meta Atom

AbstractAdaptive metasurfaces (MSs) provide immense control over the phase, amplitude and propagation direction of electromagnetic waves. Adopting phase-change materials (PCMs) as an adaptive medium allows us to tune functionality of MSs at the meta-atom length scale providing full control over MS (re-)programmability. Recent experimental progress in the local switching of PCM-based MSs promises to revolutionize adaptive photonics. Novel possibilities open new challenges, one of which is a necessity to understand and be able to predict the phase transition behavior at the sub-micrometer scale. A meta-atom can be switched by a local deposition of heat using optical or electrical pulses. The deposited energy is strongly inhomogeneous and the resulting phase transition is spatially non-uniform. The drastic change of the material properties during the phase transition leads to time-dependent changes in the absorption rate and heat conduction near the meta-atom. These necessitate a self-consistent treatment of electromagnetic, thermal and phase transition processes. Here, a self-consistent multiphysics description of an optically induced phase transition in MSs is reported. The developed model is used to analyze local tuning of a perfect absorber. A detailed understanding of the phase transition at the meta-atom length scale will enable a purposeful design of programmable adaptive MSs.

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