A. D. Shatrov

Low-frequency resonances in hollow metamaterial cylinders

The 2D problem of excitation of a hollow circular metamaterial cylinder by a filament source is analytically and numerically investigated. It is found that, when the relative permittivity and permeability are close to minus unity, high-Q resonances exist in hollow cylinders of an electrically small radius. Near- and far-field patterns are calculated. It is found that, under resonance conditions, a multilobe scattering pattern typical of superdirective antennas is formed. The influence of loss on the resonance characteristics is investigated.

Studying the properties of double-clad active cone optic fibers

A simplified model based on the weakly guiding waveguide approximation is proposed for estimating the effects occuring during propagation of radiation in a double-clad active cone optic fiber. This model is used for computer simulation, whose results agree with obtained experimental data. Practical recommendations on optimizing the shape of the cone fiber and the aperture of the pumping source for enhancement of the pump absorption efficiency are given.

Radio Absorbers Based on Magnetic Polymer Composites and Frequency-Selective Surfaces

Polymer composites filled with carbonyl iron are considered. A method is proposed for extending the operating frequency band of such radio absorbers with the help of band-reflection frequency-selective surfaces (FSSs). A functional relationship between the reflection characteristics of a radio absorber and the generalized characteristics of an FSS—the resonance frequency and Q factor—is established. On the basis of the rigorous theory of integral equations, programs are developed for computation of the reflection coefficient of a radio absorber with an FSS implemented as a biperiodic lattice with ring elements. The reflection coefficients of a series of samples are measured in the frequency band 1–10 GHz.

The effect of subwavelength localization of the electromagnetic field on the surface of a circular metamaterial cylinder

The 2D problem of excitation of a circular metamaterial cylinder by a filamentary source is numerically investigated. It is found that, for the minus one values of the relative permittivity and permeability, the field on the surface of the cylinder concentrates in a region that is located on the illuminated surface of the cylinder and that is small compared to the wavelength.

The near fields formed by a negative-metamaterial plate

A metamaterial layer with parameters ɛ and μ close to minus unity (a Veselago lens) is considered. The 2D problem of excitation of this layer by a point source is studied. Under the assumption that the thickness of the layer is much smaller than the wavelength, explicit analytic expressions for the field are obtained. Field patterns in various sections of the structure are presented.

The resonance properties of the near field in finite thin Veselago and Pendry lenses

The problem of excitation of a finite thin plate made from a metamaterial with the electrodynamic parameters ɛr ≈ −1, μr ≈ −1 and ɛr ≈ −1, μr = 1 by a point source is considered. Resonance phenomena in the near field of plates are found that are caused by the interaction of the formed surface waves. It is shown that the near field of the plate has the form of standing surface waves localized near wide faces of the plate, and the high Q factor of the observed resonances leads to the extremely strong dependence of the excited near-field amplitude on the electric and geometric parameters of the plates.

Triply degenerate surface waves in the metamaterial plate

A triply degenerate surface wave has been shown to exist in the metamaterial plate with the electrodynamic parameters ɛ0= −1.036… and μ0 > −0.964… The behavioral features of the field excited by a point source located near the plate have been revealed under the assumption that the plate parameters tend to resonant quantities and ɛ0 and μ0.

Leaking modes of guiding W-fibers with a large difference in the refractive index profiles

For a planar three-layer guiding fiber and a guiding W-fiber, comparative analysis of the characteristics of leaking modes is performed on the basis of numerical solution of the dispersion equation. It is shown that the complex plane distributions of solutions to the dispersion equation for the transverse wave numbers of leaking modes substantially depend on the geometrical and optical parameters of such structures. In particular, it is found out that a guiding W-fiber with a large step in the refractive index ensures the most effective filtering of leaking modes and the highest concentration of the guided mode field.

Electromagnetic properties of a lattice of anisotropically conducting strips with a high filling factor

A planar small-period lattice of anisotropically conducting strips separated by extremely narrow gaps is considered. An explicit analytic expression for the coefficient of reflection of a plane linearly polarized wave from this lattice is derived. Computation results illustrating the resonance properties of the structure are presented. It is shown that surface waves can propagate along the lattice. The corresponding dispersion equation is derived and analyzed.

Two-frequency resonance scattering by finite thin metamaterial plates

A finite thin plate made from a metamaterial with negative values of permittivity ɛ and permeability μ is considered. The 2D problem of excitation of the plate by a cylindrical wave is numerically investigated. It is found that the frequency dependence of the excited near field has two high-Q resonances closely spaced in frequency and that the constitutive parameters have values close to those that lead to triple (double) degeneration of a surface wave in an infinite plate. The near and far fields at the resonance frequencies are calculated.