Sergei A. Boiko

Self-consistent analysis of absorption and emission data forF A centres in alkali halides

SummaryA theory which explains self-consistently the emission and the polarization rotation of transmitted light has been developed forFA centres in crystals with cubic symmetry. Azimuthal dependences ofFA luminescence in alkali halides are very informative for determining the electron-phonon interaction as well as the parameters related to the structural and optical quality for coulour centre lasers crystals. The theoretical results are applied to the interpretation of the luminescence properties ofFA (Li) centres in KCl, RbCl and KF.

Polarized wave coupling and selection rules violation in alkali-halide crystals with F/sub A/ centers

Self-diffraction of light has been investigated in KCl with F/sub A/ centers in order to elucidate the role of F/sub A/-center kinetics in holographic recording under resonant optical excitation. It is shown that diffraction efficiency for holographic grating recorded in the spectral range of the F/sub A1/ transition can be substantially increased by populating the orientations which immediately interact with the polarized light by means of lateral illumination of the crystal with an auxiliary beam. The optimum range of auxiliary beam intensities leading to improvement of grating quality is found. Such a range is directly defined by the parameter /spl chi/, characterizing the selection rules violation for F/sub A/ center in KCl. It has been found that the experimentally determined value /spl chi/=0.04 is consistent with the self-diffraction data obtained in this paper.

Two-photon spectroscopy of Eu2+ in cubic perovskite KMgF3

Abstract Two-photon excitation of the intra-configurational f-f transitions of Eu2+ in the cubic host KMgF3 were studied. The fully resolved Stark structure of the 6 P 7 2 , 5 2 excited multiplets support the picture of a cubic environment for the majority of the Europium ions, as well as the presence of sites of lower symmetry. Transitions to the 6Dj multiplet were also measured for the first time in this host together with the temperature dependence of the line shape and peak energy position for all observed transitions.

Effect of polarization self-action in cubic crystals: peculiarities and applications

New concepts are developed to describe a wide area of nonlinear systems involving the phase relaxation peculiarities for the degenerate two-level system under the resonant optical excitation. Nonlinear susceptibility of the two-level system becomes anisotropic, and self-induced changes of polarization (SICP) are developed to the large (gigantic) magnitudes. The nonlinearities of two different natures are considered: the saturation of absorption and the resonant optical reorientation of anisotropic defects. For these particular cases, the SICP effects manifest themselves at a field much lower than that in traditional nonlinear optics. The larger magnitudes of the effects offer good possibilities for the development of optical devices based on the new physical principles. Various applications of SlOP effects are demonstrated, including the spectroscopic investigations of impure cubic crystals, optical diagnostics, optical storage, information processing, and the development of new optical devices.