Influence of the active medium on the spatial characteristics of the waveguide lasing regime in gas lasers

Theoretical and experimental investigations were made of the spatial characteristics of the waveguide lasing regime in gas discharge lasers with an inhomogeneous active medium. Selfconsistent solutions of the eikonal and transfer equations were obtained in the aberration-free approximation, taking into account the self-interaction of the radiation. It was found that for large inhomogeneities of the gain, resulting from saturation effects, the active medium itself can fulfill the role of a waveguide. Hysteresis was discovered in the dependence of the beam parameters on the level of the losses. The role of thermal effects in the formation of the mode structure of gas discharge waveguide lasers was clarified. The calculations were in good agreement with the results of experiments performed on waveguide CO₂ and He–Ne lasers having wavelengths 10.6 and 3.39 μ.