Stimulated emission in semiconductor quantum wire heterostructures.

We report the first observation of stimulated emission in quasi-one-dimensional semiconductor quantum wires. Amplified spontaneous emission and stimulated emission spectra of the GaAs/AlGaAs quantum wires exhibit fine structure arising from transitions between lateral, one-dimensional electron and hole subbands. The observed subband separations, \ensuremath{\sim}10 meV, are consistent with the calculated ones.