BLEACHING OF EXCITONS IN A (ZN,CD)SE ZN(S,SE)/(ZN,MG)(S,SE) LASER-DIODE UNDER LASING CONDITIONS/

We performed a pump-and-probe photoluminescence excitation spectroscop y of the stimulated emission of a Zn0.7Cd0.3Se single-quantum-well (SQ W) structure proven to act as an efficient room-temperature laser diod e under current injection. Excitonic absorption features in the excita tion spectra of stimulated emission are completely bleached if the sam ple is simultaneously pumped by a second laser of fixed wavelength and an intensity of only 40 kW/cm(2). The stability of excitons under las ing conditions, thus, is seriously called into question in ZnSe-based SQW laser structures even at low temperatures.