Gain and index measurements in GaAlAs quantum well lasers

Measurements of the modal gain and group index in GaAlAs single-quantum-well (SQW) lasers are presented. The elimination of substrate emission has allowed accurate results to be obtained even in the near-bandgap and below-bandgap spectral regions. Substantial lifetime broadening is observed, and the gain smoothly goes to zero as the bandgap is approached. The group velocity index measurements indicate a dispersion of -3.44 μm^-1