Bogdan A. Kochetov

Bio: Bogdan A. Kochetov is an academic researcher from Jilin University. The author has contributed to research in topics: Dissipative system & Time domain. The author has an hindex of 6, co-authored 13 publications receiving 94 citations.

Mode Expansion in Time Domain for Conical Lines with Angular Medium Inhomogeneity

Abstract: A new modiflcation of the method of Mode Expansion in Time Domain is proposed for studying transient signals propagation in conical lines (including multi-connected ones) with inhomogeneous and time-dependent medium. The method is based on expanding the flelds in spherical coordinate system into series of angular dependent modes with mode amplitudes being governed by a system of coupled evolutionary equations. The medium parameters (permittivity and permeability) are taken in a factorized form as a product of angular dependent factor and a factor that depends on time and radial coordinate. The introduced method can be applied to analysis of propagation and radiation in conical-like antennas with dielectric fllling.

Cutoff Frequencies of a Dielectric-Loaded Rectangular Waveguide With Arbitrary Anisotropic Surface Impedance

Abstract: The coupled transcendental equations describing cutoff frequencies of TE and TM modes are deduced for a rectangular waveguide with arbitrary wall impedance. In the case of TE modes, their generalization is made to a rectangular guiding structure, which possesses both distributed wall impedance and inhomogeneous dielectric loading. Effective impedance is obtained for imperfectly conducting surface incorporating periodic rectangular corrugations along the direction of mode propagation. Circular waveguide bounded by such corrugated surface and rectangular impedance waveguide are considered as numerical examples. For these waveguides, the computations performed to determine the cutoff frequencies of TE guiding modes are validated against the results of the perturbation theory and the finite-element method.

Control of dissipative solitons in a magneto-optic planar waveguide.

Abstract: We propose a mechanism to control propagation of a group of stable dissipative solitons in a nonlinear magneto-optic planar waveguide. The control is realized by means of a spatially inhomogeneous external magnetic field, which is induced by a set of direct conducting wires placed on the top of the guiding layer. The wires are extended in the direction of soliton propagation, and carry electric currents with particular piecewise constant profiles. In order to describe the soliton evolution the one-dimensional cubic-quintic complex Ginzburg–Landau equation has been adapted by tailoring an additional linear term, which is responsible for the magneto-optic effect.

Replication of dissipative vortices modeled by the complex Ginzburg-Landau equation

Abstract: Dissipative vortices are stable two-dimensional localized structures existing due to balance between gain and loss in nonlinear systems far from equilibrium. Being resistant to the dispersion and nonlinear distortions they are considered as promising information carriers for new optical systems. The key challenge in the development of such systems is getting control over vortex waveforms. In this paper we report on replication of two-dimensional fundamental dissipative solitons and vortices due to their scattering on a locally applied potential in the cubic-quintic complex Ginzburg-Landau equation. It has been found that an appropriate potential nontrivially splits both fundamental solitons and vortices into a few exact copies without loss in their amplitude levels. A remarkably simple potential having a finite supporter along the longitudinal coordinate and a double-peaked dependence on a single-transverse coordinate is found to be suitable for the replication of the two-dimensional localized structures.

Axially Symmetric Transient Electromagnetic Fields in a Radially Inhomogeneous Biconical Transmission Line

Abstract: In the present paper a novel mathematical model of physical processes of transient electromagnetic waves excitation and propagation in a biconical transmission line with radially inhomogeneous magneto-dielectric fllling is proposed. The model is based on time domain mode expansions over spherical waves. The basis functions of the mode expansions are calculated analytically. The mode expansion coe-cients are governed by Klein-Gordon-Fock equation with coe-cients depending on a radial spatial coordinate. The explicit flnite difierence time domain computational scheme is derived to calculate the mode expansion coe-cients. Dependences of cutofi frequencies of higher modes of TE and TM waves on the line geometry and dielectric fllling are studied. In order to calculate electromagnetic fleld in the line with higher accuracy, just flnite number of terms in the mode expansions is required. Electromagnetic fleld excited by the transient electric ring current is calculated in both homogeneous and radially inhomogeneous biconical transmission line. It is shown that there is a possibility to increase the bandwidth of the line via introduction of partial dielectric fllling without changing the line geometrical size.

Фізична реабілітація під час захворювань серцево-судинної системи в учнів 17 років

Abstract: У статті визначено ефективність впливу розробленої авторської програми корекції фізичної підготовленості учнів старшого шкільного віку засобами фізичної реабілітації під час захворювань серцево-судинної системи. Efficiency estimation of the developed author’s programme for high school students’ with diseases of the cardiovascular system physical fitness correction by means of physical rehabilitation is made in the article

Realization of all-optical vortex switching in exciton-polariton condensates

Abstract: Vortices are topological objects representing the circular motion of a fluid. With their additional degree of freedom, the vorticity, they have been widely investigated in many physical systems and different materials for fundamental interest and for applications in data storage and information processing. Vortices have also been observed in non-equilibrium exciton-polariton condensates in planar semiconductor microcavities. There they appear spontaneously or can be created and pinned in space using ring-shaped optical excitation profiles. However, using the vortex state for information processing not only requires creation of a vortex but also efficient control over the vortex after its creation. Here we demonstrate a simple approach to control and switch a localized polariton vortex between opposite states. In our scheme, both the optical control of vorticity and its detection through the orbital angular momentum of the emitted light are implemented in a robust and practical manner.

Realization of all-optical vortex switching in exciton-polariton condensates

Abstract: Vortices are topological objects representing the circular motion of a fluid. With their additional degree of freedom, the 'vorticity', they have been widely investigated in many physical systems and different materials for fundamental interest and for applications in data storage and information processing. Vortices have also been observed in non-equilibrium exciton-polariton condensates in planar semiconductor microcavities. There they appear spontaneously or can be created and pinned in space using ring-shaped optical excitation profiles. However, using the vortex state for information processing not only requires creation of a vortex but also efficient control over the vortex after its creation. Here we demonstrate a simple approach to control and switch a localized polariton vortex between opposite states. In our scheme, both the optical control of vorticity and its detection through the orbital angular momentum of the emitted light are implemented in a robust and practical manner.

Transverse operator method for wakefields in a rectangular dielectric loaded accelerating structure

Abstract: Cherenkov radiationgeneratedbya relativistic electronbunch in a rectangular dielectric-loadedwaveguide is analyzed under the assumption that the dielectric layers are inhomogeneous normal to the beam path. We propose a method that uses eigenfunctions of the transverse operator applied to develop a rigorous full solution for the wakefields that are generated. The dispersion equation for the structure is derived and the wakefield analysis is carried out. The formalism developed here allows the direct solution of the inhomogeneous system ofMaxwell equations, an alternative analytic approach to the analysis of wakefields in contrast to the previously used impedance method for rectangular structure analysis. The formalism described here was successfully applied to the analysis of rectangular dielectric-lined structures that have been recentlybeam tested at the Argonne (ANL/AWA) and Brookhaven (BNL/ATF) accelerator facilities.

Method of Mode Matching in Time Domain

Abstract: A new method is presented for analysis of transient electromagnetic flelds in regular structures with abrupt discontinuities. The method is based on mode expansion of the flelds in the Time Domain. The modes propagate independently in the regular parts of the structure and are coupled at the discontinuity. The main idea consists in solving 1D FDTD equations for each independent mode channel in the regular waveguides and using mode-matching at the junction cross-section in order to relate the mode amplitudes in all the channels at the same time instant via imposing boundary conditions. As examples the problems of pulse signal difiraction at a step discontinuity in a parallel-plate waveguide, difiraction at a junction of circular and coaxial waveguides, and pulse radiation of a bi-conical antenna are considered. The latter problem is treated as a junction of two conical lines (one of which is the free space) that are regular in spherical coordinates.