Generation of reflected and transmitted waves in induced superradiance

Regimes of generation of reflected and transmitted waves in induced superradiance are studied. It is shown that a back wave appears due to reflection from boundaries of the inversion region.     

Cascade photon emission in luminophores

Cascade photon emission (CPE), i.e., the production of two or more photons of visible light upon excitation by a single vacuum UV photon, allows for the creation of luminescent materials with the quantum efficiency (Q) greater than unity. Various types of CPE, both experimentally observed and theoretically modeled, are described in this work. The basic characteristics of the matrix and the activator (a rare-earth ion) required for the CPE effect are determined. The most promising CPE materials are the Pr³⁺-activated fluorides with a high coordination number for the activator. It is shown that creation of phosphors with Q > 1, which is currently of great interest from both scientific and technological viewpoints, remains highly problematic.     

Solitary waves in a nonlinear oppositely directed coupler

The propagation of pulses in the system of two tunnel-coupled optical waveguides from optically nonlinear materials one of which has a negative refractive index, while the other one, positive, is investigated theoretically. The propagation of nonlinear waves in this structure is studied based on the model of coupled modes. For linear waves, this pair of coupled waveguides behaves as a mirror resulting in the change of direction of the energy flow upon penetration of radiation from one waveguide to the other. The solutions to the system of nonlinear equations describing the stationary propagation of the solitary wave, the gap soliton, in a particular direction are found. This soliton is formed by the coupled pair of wave packets each localized in the corresponding waveguide.     

Optical bistability upon interaction of a three-component light field with a thin molecular film

The resonance interaction of a three-component electromagnetic field with a planar polymer film containing J aggregates of dyes is studied. The field consists of two counterpropagating waves traveling along the J aggregate film and a wave directed along a normal to the plane of the film. It is shown that, compared to the case of a one-component field, the polariton-phonon interaction in such a system leads to qualitatively different conditions of the occurrence of localized exciton states and bistability.     

Coherent effect in the radiation of relativistic electrons in the field of bent atomic crystallographic planes

The effect of the intense monochromatic radiation arising when relativistic electrons intersect periodically bent atomic crystallographic planes in a crystal is predicted. This effect is independent of the channeling of the particles in the crystal and is possible for relativistic positrons and electrons.     

On the 65th Anniversary of the Laboratory of Crystal Optics at the Institute of Crystallography,Russian Academy of Sciences

Crystallography Reports -     

Magnetooptical force in the resonance field formed by elliptically polarized light waves

The screening of the Coulomb interaction is studied with regard to Friedel oscillations in multicomponent electron plasma structure. A double quantum well (QW) and a superlattice are considered. The groundstate energy of a donor (exciton) in a double quantum well is calculated by a variational method as a function of the population of subbands.     

Circular dichroism spectra of langasite family crystals in the range of electronic transitions of structure defects

The absorption and circular dichroism spectra of langasite family crystals are studied. Wide bands in the range of 285–500 nm that are related to the structure lattice defects are found. For all the crystals, these bands are in approximately the same spectral region, have identical structures, and can be attributed to one type of defects formed by cation vacancies and excess oxygen atoms in the optically active positions.