A. A. Bulgakov

Dispersion properties of a periodic semiconductor structure in a magnetic field directed along the periodicity axis

The band spectrum of natural waves in a periodic structure formed by alternating dielectric and semiconductor layers is investigated for the propagation of waves at some angle with respect to a magnetic field applied along the periodicity axis. A method is presented for deriving a dispersion equation, and its properties are analyzed numerically. It is shown that, in the absence of dissipation, there are two independent spectra of natural waves in the structure being considered, and the regions of existence of various types of such waves are classified. It is established that the transmission bands of the two spectra may supplement one another or overlap. It is found that, for the chosen magnetic-field direction, there exist numerous bands of transmission of cyclotron waves.

Electrodynamic properties of a thin-film periodic structure in an external magnetic field

Reflection and transmission of light by a bounded periodically layered structure formed by periodically repeated dielectric and semiconductor layers in a magnetic field are studied. The period of the structure is assumed to be much shorter than the wavelength. The magnetic field vector is parallel to the layer plane, and the wave propagation direction is perpendicular to the magnetic field. Passage to the limit of the thin-layer structure is performed. It is shown that the structure in this case is a biaxial crystal. The properties of the reflection and transmission coefficients are studied.

Surface Electromagnetic Waves in Finite Semiconductor-Dielectric Periodic Structure in an External Magnetic Field

The speciflc features of TM-polarized surface electromag- netic waves in a flnite structure fabricated by a periodic alternating semiconductor and dielectric layers are investigated. Dispersion char- acteristics of eigenwaves are analyzed numerically and analytically. The complex Poynting energy ∞ux and the surface waves distribution are calculated. The in∞uence of geometrical and physical parameters of the structure on the properties of surface waves is studied.

Dispersion and instability of electromagnetic waves in layered periodic semiconductor structures

The effect of carrier drift on the dispersive properties and instability of electromagnetic waves and plasma polaritons in infinite layered periodic semiconductors are considered. It is assumed that in similar semiconductor layers, carriers drift parallel to the interfaces. Drift waves are shown to have a specific band structure of the spectrum. The dispersive properties of collective plasma polaritons under drift are considered, the instability of the polaritons and drift waves is studied, and the instability increments are determined.

Nonlinear excitation of the second harmonic in a semiconductor superlattice placed into a magnetic field

The nonlinear interaction of waves in a periodic structure placed into a magnetic field is considered. The structure is comprised of alternate semiconducting and insulating layers. The three-wave interaction technique is applied to studying the nonlinear processes. It is shown that nonlinear phenomena in media with translational symmetry and in homogeneous media differ. Conditions for the resonant interaction between the first and second harmonics are analyzed. It is found that the second harmonic is generated when the interacting first spatial harmonics both co-and counterpropagate, which is possible only in periodic structures. Resonance events improving the generation efficiency are discussed.

The phenomenon of conical refraction in a thin-layer periodic semiconductor-dielectric structure in a magnetic field

The propagation of electromagnetic waves along the optical axes of a thin-layer periodic semiconductor-dielectric structure in an external magnetic field (i.e., under conditions of external and internal conical refraction) has been investigated. It is shown that the conditions for conical refraction can be implemented in certain regions by changing the external magnetic field, wave frequency, and thickness of the layers forming the structure. By varying the above-mentioned characteristics, one can efficiently control the conical refraction parameters; in particular, the opening angles of the cone of internal and external conical refraction and the inclination of the optical axes with respect to the periodicity axis can be varied in a wide range. The results of this study may be useful for designing millimeter-wave, submillimeter-wave, and IR devices.

Surface electromagnetic waves at the interface between two dielectric superlattices

The electrodynamic properties of the interface between two periodic dielectric superlattices are studied. It is shown that the interface may serve as a guide for an electromagnetic wave whose field decays exponentially on both sides of the plane of the interface. The field and power flux distributions, as well as the frequency dependence of the field penetration depth, are studied.

Dispersion properties of cyclotron waves in periodic semiconductor-insulator structures

The band spectrum of cyclotron waves propagating in a periodic layered semiconductor-insulator structure at an angle to an external magnetic field that is applied perpendicularly to the layers is calculated for two relationships between the characteristic frequencies of the semiconductor: ωH>ωP and ωH<ωP. The wave field distributions across the layers and over the period of the structure are analyzed. In both spectra, transmission bands arise when the conditions for dimensional resonance across the semiconductor layer are fulfilled. The graphic solution of the dispersion relation demonstrates that the cyclotron wave spectrum can be subdivided into two spectra of normal waves according to the Bloch wavenumbers of the periodic structure. The cases where the band spectra complement each other or overlap are considered.

Excitation and observation of ball-lightning type spherical formations

Experimental research results of discharge processes in liquids are presented. Excitation conditions of spherical plasma formation are met on the water-air boundary. Theoretical model of complex wave excited in layer media, is proposed to explain the plasmoid existence. It is shown that such structure can be formed by standing acoustic wave, which occurs during electrical discharge in water container.

Transmission and reflection of electromagnetic waves from ferrite-semiconductor periodic multilayered structures

The conventional approach to characterisation of the wave phenomena in metamaterials (MMs) is based upon the approximation of homogenised medium. When MMs are composed of the arrays of resonant scattering elements, with their sizes much smaller than the wavelength of the propagating electromagnetic wave, MMs can be described by the effective constitutive parameters of an equivalent continuous medium. Although a number of the homogenisation procedures have been proposed for the effective linear parameters of MM such as the effective permittivity and permeability, their physical meaning and applicability limits are still debated in the literature. In this paper, we present the results of the theoretical and experimental study of transmission spectra of electromagnetic waves propagating through a finite periodic layered structure, composed of the ferrite and semiconductor layers, which is subjected to external magnetic bias. We consider both fine-layered structure and that with the thickness of the layers being of the same order of magnitude as the length of incident electromagnetic wave. The aim of the presented work is to consider new types of waves formed in the area of transfer between photonic crystal (PC) and homogenized medium. Using results of theoretical and experimental investigations we compare the theoretical model outcomes with the real processes and define the conditions of applicability of the theory.