Ultraviolet stimulated emission and optical gain spectra in CdxZn1−xS-ZnS strained-layer superlattices

Stimulated emission at 374.9 nm has been observed in an optically pumped Cd0.22Zn0.78S-ZnS strained-layer superlattice at room temperature. Using a pump-and-probe technique with nanosecond excitation pulses, optical gain has also been observed at the tail part of the n=1 heavy-hole exciton absorption spectrum in the presence of the clear absorption peak of the exciton. Our experimental results suggest that the stimulated emission originates from excitonic gain.