Influence of femtosecond superradiant pulses on spontaneous emission spectra of GaAs/AlGaAs heterostructures

The spectra of spontaneous emission accompanying the generation of femtosecond superradiant pulses in GaAs/AlGaAs heterostructures are studied. It is clearly demonstrated that spontaneous emission spectra of electron–hole pairs, which have been left in the semiconductor after the formation of a coherent collective e–h state, correspond to the strong overheating of carriers. This phenomenon can be explained by the effect of dynamic cooling and nonequilibrium condensation of collectively paired carriers at the bottoms of the bands during the superradiant emission, which was observed earlier.