Interaction of light with a semiconductor thin film, taking into account concentration gain of the dipole moment of the excitonic transition

The peculiarities of nonlinear transmission of ultrashort pulses of resonan ce laser radiation by a semiconductor thin film in the excitonic spectral r egion have been studied, taking into account the exciton-phonon interaction and concentration gain of the dipole moment of the excitonic transition. I t has been shown that under exact resonance conditions the film transmits o nly the leading edge of the incident rectangular pulse and completely refle cts the remaining part. For a nonzero off-resonance, a residual transmissio n occurs. A series of possibilities for transforming Gaussian pulses is pre dicted. The state equations for steady-state bistable transmission (reflect ion) have been derived, and the stability of the solutions has been studied . A theorem of areas, which predicts area restriction of the transmitted pu lses, has been stated; namely, the transmitted pulse area cannot exceed pi/ 2. (C) 2000 MAIK "Nauka/Interperiodica".