Transformation of electromagnetic radiation at moving inhomogeneities of a medium

The possibility of a significant up-conversion of the electromagnetic-radiation frequency due to its Doppler shift by ultrarelativistic nonlinear-medium inhomogeneities induced by high-intensity counterpropagating radiation pulses is analyzed. It is shown that the efficiency of parametric redistribution increases resonantly as the velocity of the inhomogeneity approaches the phase velocity of the high-frequency radiation.     

Transformation of optical radiation by fast-moving smooth inhomogeneities of a medium

For the problem of the reflection and transmission of monochromatic radiation by a moving smooth inhomogeneity of parameters of a motionless transparent medium, transport equations are derived and an approximate solution to these equations is obtained for the case of weak reflection. Estimates of the effects for quartz in the transparency region are given.     

Relativistic scattering of electromagnetic radiation by inhomogeneities of the velocity of motion of the medium

Analysis of the relativistic scattering of electromagnetic radiation by inhomogeneities of the velocity of the motion of a medium is carried out. The characteristics of the scattering of a plane monochromatic wave by a rotating dielectric cylinder surrounded by an immobile medium with a refractive index the same as that of the cylinder are calculated. The differential scattering cross section is found. It is shown that the rotation of particles with actual parameters may yield a significant contribution to the scattering, of the same order of magnitude or larger than the contribution made by Rayleigh and Raman scattering.     

Anisotropy of the velocity space of electromagnetic radiation in a moving medium

Anisotropy arising in moving media is considered. In these media, the phase velocity of light nonlinearly depends on the velocity vector field of the medium due to anisotropic binding forces between lattice atoms. Observations of the optical anisotropy of light in a rotating optically transparent medium are discussed. Laser radiation with wavelength ?? = 0.632991 ± 1 × 10^?7 ??m propagating in an interferometer was passed through a rotating optical disk D = 62 mm in diameter. The projection of the beam??s path length in the medium onto the flat surface of the disk is l = 41 mm; the refractive index of the glass and its thickness are, respectively, n = 1.71250 for ?? = 632.8 nm and 10 mm; and the angle of incidence of the beam on the flat surface of the disk is ?₀ = 60°. The optical disk is rotated in two directions, and its rotation frequency may reach 250 Hz. Experimental data confirm the linear dependence of the fringe shift on the velocity of the medium up to 29.6 m/s. The measurement accuracy is sufficient to detect angular variations ??? = 3 × 10^?5 in the position of fringes at a fixed rotation velocity of the optical disk.     

On scattering of electromagnetic radiation by inhomogeneities of the velocity of motion of the medium

Analysis of the scattering of a plane monochromatic electromagnetic wave by an inhomogeneity of the velocity of motion of the medium is carried out. The inhomogeneity corresponds to the rotation of a finite portion of the medium with a constant angular velocity under the conditions of spatial homogeneity of the permittivity and the permeability. The case of oblique incidence of the wave is studied. The scattering cross sections for an inhomogeneity having the shape of a cylinder or a sphere of different dimensions are found for different angles of incidence of radiation.     

Backscattering of electromagnetic waves by large-scale inhomogeneities in a periodically inhomogeneous medium

It is shown that backscattering of electromagnetic waves is possible in a periodically inhomogeneous medium by random inhomogeneities whose scale is greater than the wavelength. A small scattered field emerges in the case of appearance of the Bragg cavity when the periodic layer is a matching system for the incident wave. Scattering is effective even for inhomogeneities whose scale is much greater than the Fresnel radius of the inhomogeneous layer. The correlation radius of the scattered field can also be that large. Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 10, pp. 1230–1240, October, 1997.     

Nonstationary heating of a plane-layered medium by pulsed electromagnetic radiation

Nonstationary heat exchange in a nontransparent plane-layered medium irradiated with a directional beam of pulsed radiation is investigated theoretically. The radiation is absorbed on the irradiated surface, which becomes a distributed source of heat. The propagation of the heat into the layers is described by the heat-conduction equation with nonlinear boundary conditions, which take into account convection and heat exchange with the radiation. Dimensionless parameters, on which the solution depends, are obtained, and their effect on the change of the surface temperatures of the layers with time for one- and two-layered media and also on the heat pulse transmitted through the medium is analyzed.M. V. Lomonosov Moscow State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 115–121, November, 1992.     

Dispersion process of electromagnetic waves in a moving medium

The propagation of electromagnetic waves in a moving isotropic plasma and in a moving magnetoactive plasma is considered using the invariant methods of tensor analysis. Expressions are obtained for the dielectric permittivity tensor, the dispersion equations, and the refractive indexes of electromagnetic waves in these media. Using these results it is possible to establish corrections to the angular displacement which occurs when radiation passes through a moving electron plasma.Published from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 1, pp. 121–129, January, 1996.     

介质运动时的电磁规律

静止时线性、均匀、各向同性的介质，当它运动时变得不再各向同性，其标志是光线和波法线分离，波面形状由球面变成椭球面．本文给出了非各向同性介质与介质运动速度间的定量关系，导出了电磁波在运动介质表面反射和折射的普遍规律．并且就介质的运动方向与介质表面垂直或平行两种特殊情形进行了较为详细的分析。     

Induced radiation by charged particles moving in a plane electromagnetic wave

It is shown that when a charged particle moving in the field of a plane electromagnetic wave is subjected to another electromagnetic wave, incident at some angle with respect to the first, induced radiation and absorption occur. Under certain conditions the induced radiation predominates over the absorption.Translated from Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 50–53, September, 1969.The authors thank professor I. M. Ternov for useful discussions.     

Transformation of nonlinear sawtooth waves in a medium with refractive inhomogeneities

Theexact solutions of intensive sawtooth waves and beams in a medium with a sound speed inhomogeneity have been found. It has been shown that the focusing on the medium inhomogeneity is strongly pronounced for a single pulse, resulting in the formation of narrow high-amplitude areas. It has been determined that the refractive infomogeneity can lead to a shift of the amplitude maximum of the initial focused beam and the transformation of the converging beam into a dispersing one.     

Radiation reflection from inhomogeneities moving in a medium with a plasma dispersion law

The dependence of the complex frequency of radiation reflected from an inhomogeneity moving in a medium on the frequency of the incident radiation is found for inhomogeneous wave regimes. Explicit expressions for the plasma dispersion law of the medium are presented. The complex Doppler effect, where one (real) frequency of the incident radiation corresponds to two complex frequencies of the reflected radiation, is demonstrated.     

Cerenkov radiation of a spatially extended charged bunch moving along the axis of a cylindrical channel in a transparent medium

Relations are obtained which determine the electromagnetic field produced by an axially symmetric bunch of charged particles moving along the axis of a cylindrical channel in a transparent medium. The problem of the Cerenkov radiation of such a bunch is investigated and relations are obtained for the intensity of this radiation.In conclusion the author thanks Professor A. A. Sokolov for discussing the results.     

Cherenkov radiation by the charged particle moving in moving Hermitian medium

Detailed theoretical investigation and computer calculations on the Cherenkov radiation (CR) in moving Hermitian medium (CRMH) are presented in this paper. It has been found that, similar to that in stationary Hermitian medium (CRH) case, there are two modes in the CRMH; in general, only one of them is radiative mode, another one is local field, and the comparison of the two modes is given in the paper. The small absorption of CRMH mainly results in the Gaussian-like field intensity pattern. And the group velocity in the CRMH is always slower than the phase velocity in the moving HM, so the fine inner structure occurs. Comparing the behaviors of CRMH and CRH, we have found that the movement of the Hermitian medium (HM) brings significant influences on the CR, so there are some interesting characteristics of CRMH, such as in the CRMH; the radiation power of the “o” mode is much higher than that of “e” mode. And because of the relativistic Doppler effect, the frequency region where both modes are radiative becomes quite different from that for CRH.     

运动介质的电磁性质方程

应用电磁场张量、电磁感应张量和它们的对偶张量讨论运动介质的电磁性质方程,指出D=εE和B=μH在运动介质中不成立,给出运动介质电磁性质方程的协变形式、向量形式.     

Reflection of radiation from moving inhomogeneities of a medium: Inhomogeneous wave regimes and the ambiguity problem of doppler frequency shifts

Using the Boltzmann equation in the relaxation-time approximation for the one-electron distribution function in combination with the coupled Maxwell equations for the electromagnetic field, we obtained a system of equations describing the propagation of ultimately short optical pulses through a semiconductor superlattice in an external magnetic field. It is shown that the initially linearly polarized light pulse propagating in the sample gives rise to the field of orthogonal polarization. The dynamics of propagation of the pulse in both polarizations is studied. The effects produced by the lattice geometry are revealed.