Reflection coefficient and depth extinction coefficient of a semiinfinite layer of a dispersed medium

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 1, pp. 137–142, January, 1990.     

Propagation and scattering of waves in a strongly nonuniform nonabsorbing medium

Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 3, pp. 307–313, March, 1989.     

Self-induced transparency in a dispersive medium

The evolution of the electromagnetic field in a two-level medium occurring in a matrix with finite response time has been studied. An integrable variant of the Maxwell-Bloch equations with allowance for nonlinear dispersion is derived and solved using the inverse scattering problem. It is shown that the nonlinear dispersion caused by the finite response time of the matrix yields a new possibility of controlling soliton parameters. A particular case of the constructed model can be used to describe field pulses in the parameter domain that occurs between the regions of applicability of the quasi-monochromatic approximation and the approximation of unidirectional propagation of pulses with durations on the order of the oscillation period.     

The influence of the packing density of absorbing inclusions into a dispersive medium on its absorption coefficient

Using an approach that is similar to the approximation of anomalous diffraction of physical optics, we have obtained analytical relations for the absorption coefficients of homogeneous and dispersive media that contain equal amounts of light absorbing matter. We show that these relations depend on the packing density of inclusions, which is characterized by the fraction of the area or volume that they occupy. It has been found quantitatively that differences between absorption coefficients of the homogeneous and dispersive media increase with increasing optical size of inclusions and decrease at large packing densities. We note that it is important to take into account the obtained dependences in spectroscopic investigation of the dispersive medium near intense absorption bands of its components. Theoretical and experimental results are compared with each other, and it is shown that they reasonably agree with each other qualitatively and quantitatively. Our study may be useful for specialists in biomedical optics, ocean physics, physics of the Earth’s surface, and scientific and applied photography.     

Surface impedance of a spatially dispersive medium

The surface impedance for non-normal specular reflection from a spatially dispersive medium is calculated using the additional boundary condition of vanishing polarization at the surface. There is no dependence on the longitudinal dielectric constant for either polarization directions of the electric field in contrast to the formula derived by Kliewer and Fuchs.     

Entangled two-photon wave packet in a dispersive medium

We report an experimental study of group-velocity dispersion effect on an entangled two-photon wave packet, generated via spontaneous parametric down-conversion and propagating through a dispersive medium. Even in the case of using cw laser beam for pump, the biphoton wave packet and the second-order correlation function spread significantly. The study and understanding of this phenomenon is of great importance for quantum information applications, such as quantum communication and distant clock synchronization.     

Dispersive solutions of the linear wave equation for a nonabsorbing dispersion-free unbounded medium

The existence of non-one-dimensional nondispersive and dispersive solutions of the “classical” linear wave equation is discussed and substantiated. Procedures for finding the two classes of solutions are formulated, and examples of using these procedures are presented.     

Current-voltage characteristic of a corona discharge in a dispersive medium

The current-voltage (I–V) characteristic for a corona discharge in a dispersive medium is derived on the basis of the Townsend assumptions for a coaxial cylindrical system. The expressions found can be used to find the discharge current in a dispersive medium and the condition for total discharge cutoff over a wide range of concentrations of the dispersive phase. The calculated results are found to be in satisfactory agreement with experiment.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 3, pp. 53–58, March, 1969.     

Dynamics of optical pulses in a dispersive chiral medium

The dynamics of frequency-modulated pulses in an isotropic nonreciprocal chiral medium is studied. It is shown that the discrepancy between the group velocities and carrier frequencies of the circular components of the pulse causes it to split up both along the fiber and in the spectral domain. The strong dependence of the material parameters on the pulse frequency may lead to the asymmetric dynamics of the electric and magnetic fields of the pulse in different frequency intervals. For both components of the wave field, envelopes moving with a supraluminal speed may arise.     

Transmission of quasi-monochromatic light wave through dispersive medium and measurement of refractive index

Relations used in the measurements of the refractive index in a non-absorbing dispersive medium are discussed, taking into account the quasi-monochromaticity of the light wave. It is shown that when interference methods using compensation are employed, it is always necessary to allow for corrections for dispersion. Relations describing the diffraction of a ray at the boundary of vacuum and a non-absorbing dispersive medium can be obtained only from the continuity of the Poynting vector at the interface of these media. The stationary phase method may lead to erroneous conclusions. The group velocity vector, which for diffraction describes correctly not only the absolute magnitude but also the direction of this velocity in a dispersive non-absorbing medium, is of the form $$v_g = \frac{{k(\omega _0 )}}{{|k|}}|\upsilon _g |$$ whereω ₀ is the frequency belonging to the maximum amplitude of a given quasi-monochromatic wave.     

Studying the structure of a dispersive medium using multiple light scattering data (for an arbitrary incident light direction)

A scheme for computing the size distribution function of scattering particles is developed. The procedure is based on the use of experimental multiple light scattering data for an arbitrary direction of radiation incidence on the medium.The author considers it his pleasant duty to thank Prof. K. B. Tolpygo for his constant interest in the present study.     

Impurity combinational absorption of a multiphoton field in a dispersive medium

It is shown that the absorption of one field quantum by an impurity atom in a dispersive medium stimulates transitions of the two quanta between different branches of the energy spectrum. The wave vectors of the quanta do not change in this process.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 78–82, February, 1986.     

Electromagnetic radiation of a charged tachyon moving in a dispersive medium

At the present time a number of studies [1–6] have considered the possible properties of ultrarelativistic tachyon particles. In particular, [5, 6] were dedicated to analysis of the radiation of charged tachyons in a vacuum. The goal of the present study is to analyze the radiation emitted by charged tachyons in an immobile dispersive medium. We will consider the following problem: a charged particle moves with velocity v in an immobile dispersive medium and at time t=0 decays to neutral particles and a charged tachyon which moves at a velocity v₀. The tachyon in turn, because of collisions with neutral particles of the medium, at time t= forms a charged particle (electron) also moving with velocity v.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 130–134, June, 1978.In conclusion, the author expresses his sincere thanks to Professor Ya. P. Terletskii for his interest and aid in the study.