Spontaneous and stimulated radiation in semiconductors and multiplasmon optical transitions

A generalized theory of multiplasmon optical transitions in direct gap semi conductors is developed for a degenerate electron-hole plasma using the cum ulant expansion method and fluctuation-dissipation theorem. It is shown tha t a multiplasmon light absorption causes the red shift obeying Urbach's rul e. Theoretical spectra coincide with experimental data. Spectral line shape s of the spontaneous and stimulated radiation produced by band-to-band mult iplasmon recombination of e-h pairs are calculated A novel multiplasmon con cept of an intrinsic absorptive optical bistability is comprehensively disc ussed.