L D Mikheev

Photodissociation XeF laser operating in the visible and UV regions

The results of experimental and theoretical investigations of the photodissociation XeF laser operating in the visible and UV regions and pumped by the radiation of an open discharge initiated by an electric explosion of thin metal wires are reported. A detailed description of the laser design and experimental techniques is given. The analysis of the energy balance in the XeF laser on the basis of measurements of energetic parameters of laser radiation and the pump source are performed. The results of optical investigations of the active medium aimed at the study of the interaction of high-power fluxes of pump radiation with the absorbing active medium are presented. This interaction forms free-running bleaching and inversion waves in the active medium. Spectral, spatial, time, and energy characteristics of laser radiation on theB-X(λ=353 nm) andC-A(λ=480 nm) transitions of XeF are investigated. The instantaneous laser efficiency with respect to the electrical power feeding the pump source is shown to be about 1%. The specific energy of laser radiation on theC-A transition in the blue-green region was 8.5 J/liter for a total laser energy of 14.5 J. The specific energy of radiation on theB-X transition in the UV region was 16.5 J/liter for a total energy of 28 J.Kinetic models of the optically pumped XeF laser describing its operation on both transitions are developed. They allow calculations of unsaturated gain, output energy, and laser efficiency.

Frank–Condon principle and adjustment of optical waveguides with nonhomogeneous refractive indices

The adjustment of two different selfocs is considered using both exact formulas for the mode-connection coefficients expressed in terms of Hermite polynomials of several variables and a qualitative approach based on the Frank–Condon principle. Several examples of the refractive-index dependence are studied and illustrative plots for these examples are presented. The connection with the tomographic approach to quantum states of a two-dimensional oscillator and the Frank–Condon factors is established.

Optical pumping of chemical HF lasers on the basis of NF{sub 3}-H{sub 2} and ClF{sub 5}-H{sub 2} mixtures by an open surface discharge in the bleaching-wave mode

Lasing on HF upon optical pumping by emission of an open discharge, using NF3 and ClF5 as donors of fluorine atoms, was obtained for the first time in a chemical laser and the bleaching-wave mode was realised in a chemical HF laser. An open surface discharge was used as a pump source. The velocity of the bleaching wave, which was formed under its action, reached ~8 km s-1. The formation of this wave leads to a rapid (with an ultrasonic velocity) replacement of the working medium in the lasing region, which provides a quantum laser efficiency close to unity. The optimum compo-sition of the working mixture was found to be NF3:H2:Kr =6:10:125 Torr. For this composition, the output laser energy in a 3.2-μs pulse reached ~0.4 J and the specific output energy was 3.5 J litre-1. Approximately the same output characteristics of laser emission (0.35 J in a 3.5-μs pulse in the ClF5:H2:Kr=3:20:50 Torr mixture) were obtained in the system using ClF5 as donors of fluorine atoms.