Excitonic molecules and stimulated emission in a ZnSe single quantum well.

Spectroscopy on a single ZnSe quantum well characterized by a sharp exciton resonance (\ensuremath{\Delta}E=0.6 meV) shows how a gas of interacting excitonic molecules induces blue-green laser emission in an optically pumped heterostructure at cryogenic temperatures. Spectrally resolved four-wave-mixing experiments yield a molecular binding energy of 5 meV. However, the lasing occurs in an electron-hole density regime, where strong many-exciton interaction effects are evident. \textcopyright{} 1996 The American Physical Society.