Random gain medium with reflecting boundary

Abstract

The effect of a reflecting boundary on the generation threshold of a random gain medium is analysed for both specular and diffuse reflection, the latter corresponding to feedback scattering from a passive boundary layer. The feedback effect is significant for non-diffusive transfer (optically thin layer) but small in the diffusion regime unless 1−R≪ 3 γ , where γ is the gain parameter, with a maximum reduction by a factor of two for a perfectly reflecting boundary. A second reflecting boundary further reduces the threshold, the reduction depending on the optical parameters of the medium.