Volodymyr I. Fesenko

Gaussian beam tunneling through a gyrotropic-nihility finely stratified structure

The three-dimensional Gaussian beam transmission through a ferrite-semiconductor multilayer structure in the Faraday geometry is considered. The beam field is represented by an angular continuous spectrum of plane waves. In the long-wavelength limit, the studied structure is described as a gyrotropic medium defined by the effective permittivity and effective permeability tensors. The investigations are carried out in the frequency band where the real parts of the diagonal elements of both effective permittivity and effective permeability tensors are close to zero. In this frequency band the studied structure is referred to a gyrotropic-nihility medium. It is found out that a Gaussian beam can pass through such a system practically without any distortion.

Coexistence of bulk and surface polaritons in a magnetic-semiconductor superlattice influenced by a transverse magnetic field

It is demonstrated that the effect of coexistence of bulk and surface polaritons within the same frequency band and the wavevector space can be achieved in a magnetic-semiconductor superlattice, providing a conscious choice of characteristic resonant frequencies and material fractions of the structures underlying components as well as geometry of the external static magnetic field. The study is based on the effective medium theory, which is involved to calculate dispersion characteristics of the long-wavelength electromagnetic modes of ordinary and extraordinary bulk polaritons, and hybrid surface polaritons with dominant longitudinal component of either magnetic (HE) or electric (EH) field derived via averaged expressions with respect to the effective constitutive parameters of the superlattice.

Optical characterization of the aperiodic multilayered anisotropic structure based on Kolakoski sequence

The one-dimensional aperiodic structure is considered which is formed by stacking together chiral and achiral layers according to the Kolakoski self-generation scheme. Numerical simulations are carried out for different structure configurations to reveal the dependence of the optical characteristics of the system on the generation stage, frequency, chirality parameter, and the angle of wave incidence.

Dispersion features of complex waves in a graphene-coated semiconductor nanowire

Abstract The dispersion features of a graphene-coated semiconductor nanowire operating in the terahertz frequency band are consistently studied in the framework of a special theory of complex waves. Detailed classification of the waveguide modes was carried out based on the analysis of characteristics of the phase and attenuation constants obtained from the complex roots of characteristic equation. With such a treatment, the waves are attributed to the group of either “proper” or “improper” waves, wherein their type is determined as the trapped surface waves, fast and slow leaky waves, and surface plasmons. The dispersion curves of axially symmetric TM0n and TE0n modes, as well as nonsymmetric hybrid EH1n and HE1n modes, were plotted and analyzed in detail, and both radiative regime of leaky waves and guided regime of trapped surface waves are identified. The peculiarities of propagation of the TM modes of surface plasmons were revealed. Two subregions of existence of surface plasmons were found out where they appear as propagating and reactive waves. The cutoff conditions for higher-order TM modes of surface plasmons were correctly determined.

Bi-hyperbolic isofrequency surface in a magnetic-semiconductor superlattice

The topology of isofrequency surfaces of a magnetic-semiconductor superlattice influenced by an external static magnetic field is studied. In particular, in the given structure, topology transitions from standard closed forms of spheres and ellipsoids to open ones of Type I and Type II hyperboloids as well as bi-hyperboloids were revealed and analyzed. In the latter case, it is found out that a complex of an ellipsoid and bi-hyperboloid in isofrequency surfaces appears as a simultaneous effect of both the ratio between magnetic and semiconductor filling factors and magnetic field influence. It is proposed to consider the obtained bi-hyperbolic isofrequency surface as a new topology class of the wave dispersion.

Dispersion properties of Kolakoski-cladding hollow-core nanophotonic Bragg waveguide

Abstract A comprehensive analysis of guided modes of a novel type of a planar Bragg reflection waveguide that consists of a low refractive index guiding layer sandwiched between two finite aperiodic mirrors is presented. The layers in the mirrors are aperiodically arranged according to the Kolakoski substitution rule. In such a waveguide, light is confined inside the core by Bragg reflection, while dispersion characteristics of guided modes strongly depend on aperiodicity of the cladding. Using the transfer matrix formalism bandgap conditions, dispersion characteristics and mode profiles of the guided modes of such a waveguide are studied on the GaAs/AlAs and Si/SiO2 epitaxial platforms, which are compatible with hybrid and heteroepitaxial frameworks of silicon photonics.

Modal Phenomena of Surface and Bulk Polaritons in Magnetic- Semiconductor Superlattices

We discuss peculiarities of bulk and surface polaritons propagating in a composite magnetic-semiconductor superlattice influenced by an external static magnetic field. Three particular configurations of magnetization, namely the Voigt, polar and Faraday geometries are considered. In the long-wavelength limit, involving the effective medium theory, the proposed superlattice is described as an anisotropic uniform medium defined by the tensors of effective permittivity and effective permeability. The study is carried out in the frequency band where the characteristic resonant frequencies of the underlying constitutive magnetic and semiconductor materials of the superlattice are different but closely spaced. The effects of mode crossing and anti-crossing in dispersion characteristics of both bulk and surface polaritons are revealed and explained with an assistance of the concept of Morse critical points from the catastrophe theory.

Dispersion relations for bulk and surface polaritons in a magnetic-semiconductor superlattice

Dispersion relations for both bulk and surface polaritons in a subwavelength magnetic-semiconductor structure which is placed in an external static magnetic field, applied parallel to the boundaries of the layers are studied. It has been shown that the conditions of simultaneous existence of bulk and surface polaritons in the same spectral range can be reached in the system under consideration, providing a conscious choice of the constitutive parameters and material fractions for both magnetic and semiconductor subsystems.

Anomalous dispersion of polaritons in a magnetic-semiconductor superlattice

Dispersion properties of both bulk and surface polaritons at the interface between vacuum and ferrite-semiconductor superlattice are studied. The superlattice is considered to be influenced by an external static magnetic field in the Voigt geometry. In order to derive tensors of effective relative permeability and effective relative permittivity of the structure under study the homogenization procedure from the effective medium theory is engaged. Peculiarities of polariton dispersion features at a particular extreme gyrotropic-nihility state are revealed and explained.