Vladimir V. Yachin

Method of integral functionals for electromagnetic wave scattering from a double-periodic magnetodielectric layer

A numerical method in the frequency domain is developed for analyzing three-dimensional gratings using the concept of a double-periodic magnetodielectric layer. The method is based on the three-dimensional volume integral equations for the equivalent electric and magnetic polarization currents of the assumed periodic medium. The integral equations are solved by using the integral functionals related to the polarization current distributions and the technique of double Floquet-Fourier series expansion. Once the integral functionals are determined, the scattered fields outside the layer are calculated accordingly. The unit cell of the layer comprises several parallelepiped segments of materials characterized by the complex-valued relative permittivity and permeability of step function profiles. The arbitrary profiles of three-dimensional dielectric or metallic gratings can be flexibly modeled by adjusting the material parameters and sizes or locations of the parallelepiped segments in the unit cell. Numerical examples for various grating geometries and their comparisons with those presented in the literature demonstrate the accuracy and usefulness of the proposed method.

Characterization of CFRP Thermal Degradation by the Polarization-Frequency Reflectometry Method in Subterahertz Frequency Range

We investigate the carbon fiber reinforced plastics (CFRP) thermal degradation using the polarization-frequency reflectometry (PFR) method in subterahertz frequency range. The setup that realizes the PFR method is developed and includes the sample scanning by a quasi-optical wave beam with various polarizations and frequencies. The CFRP thermal degradation can be detected in the 260 °C-300 °C temperature range using the PFR method confidently enough. Applying full-wave simulation of a plane wave scattering from a CFRP sample with the aid of the integral functional technique, we show that the temperature dependence of the reflection coefficient is due to the change of the CFRP filler permittivity.

Resonant response in mechanically tunable metasurface based on crossed metallic gratings with controllable crossing angle

We report on a modern class of mechanically tunable planar metamaterials comprising resonating units formed by crossed metallic strip gratings. We observe a resonant response in transmission spectra of a linearly polarized wave passing through a system of crossed gratings in the microwave regime. Each grating consists of an array of parallel metallic strips located on the top of a dielectric substrate. It is revealed that the resonant position appears to be dependent on the angle of crossed gratings. It is found theoretically and experimentally that the resonant shift on the frequency scale appears as a result of increasing in the length of the resonating portion of the parallelogram periodic cell formed by the crossed metallic strips with decreasing crossing angle. The proposed design can be used in innovative types of planar metamaterials and filters.

Polarization conversion by metamaterial composed of a periodic array of metallic square helixes embedded in a dielectric layer

The problem of the plane-wave scattering from a 3-D metamaterial layer composed of metallic square helixes periodically embedded in a dielectric layer was solved by the full-wave method of integral functionals. It was shown that such a structure is able to rotate the electric-field intensity vector. The increase in the length of the helix makes it possible to achieve almost complete polarization conversion. The polarization conversion has a resonance character.

Plane wave scattering by a double-periodic gyromagnetic layer analyzed by the integral functional method: Full-wave solution

We obtained full-wave numerical solution of the problem of the plane wave scattering by a double-periodic gyromagnetic layer with the aid of the method of integral functionals. Using this technique it we found the layer thicknesses corresponding to nearly total transmission in a very wide range of the angles of plane wave incidence.

Fano-shape grating resonances of 3D infinite double-periodic grating of thin dielectric bricks

We study the plane wave scattering from double periodic dielectric layer located in free space and illuminated by a linearly polarized plane wave. For the problem solution, we use the method of integral functional based on the vector volume integral-differential equations for the equivalent electric and magnetic polarization currents of the assumed periodic medium. Reflectance and transmittance as a function of the normalized wavelength and the grating parameters are analyzed. Extraordinary sharp grating-type resonances are revealed in the TM- and TE-polarized wave scattering near but not equal to the Rayleigh wavelengths of non-zero diffraction orders.

Experimental study of thermal degradation influence on carbon fiber reinforced plastics reflectivity in sub-terahertz frequency range

In this paper, we investigate an ability of the detection of carbon fiber reinforced plastics (CFRP) thermal degradation using polarization-frequency reflectometry method (PFR) in sub-terahertz frequency range (0.1-0.2 THz) for non-destructive testing of the CFRP samples.

Three- dimensional Gaussian beam with circular cross section scattered from double-periodic magnetodielectric slab at a small angle of incidence

The problem of scattering of 3-D Gaussian beam incident at a small angle onto a double-periodic magneto-dielectric clab has been formulated and solved. The new formulas for incident and scattered 3-D Gaussian beam fields in the form of the single integrals have been derived. They allow to reduce the time spent upon the numerical calculations of the incident and scattered beam fields and improve their accuracy. The calculations of the obliquely incident 3-D Gaussian beam onto magneto-dielectric slab and reflected from it using derived formulas are illustrated in figures presented in the paper.

Faraday rotation enhancement by gyrotropic metasurface

We obtained full-wave numerical solution of the plane wave scattering from two-layered structure performed as double-periodical array of gyrotropic parallelepipeds on dielectric layer by the method of integral functionals. It is shown that such structure at the resonant frequency demonstrates mostly complete polarization conversion of the transmitted plane wave with a significant transmission coefficient. It is demonstrated numerically that the resonance frequency of the given structure can be controlled by varying the thicknesses of the gyrotropic and dielectric layer.

Plane wave scattering from a double-periodic gyrotropic layer

We obtained full-wave solution of the problem of the plane wave scattering from a double-periodic gyrotropic layer by the method of integral functionals. Using this technique it was shown that the Faraday rotation becomes extraordinary large at the frequencies of the grating-type resonances.