Role of a high gain of the medium in superradiance generation and in observation of coherent effects in semiconductor lasers

A theoretical model of superradiant pulse generation in semiconductor laser structures is developed. It is shown that a high optical gain of the medium can overcome phase relaxation and results in a built-up superradiant state (macroscopic dipole) in an assembly of electron-hole pairs on a time scale much longer than the characteristic polarisation relaxation time T2. A criterion of the superradiance generation is the condition αcmT2>1, where α is the gain coefficient and cm is the speed of light in the medium. The theoretical model describes both qualitatively and quantitatively the author's own experimental results. (physical basis of quantum electronics)