GAIN, REFRACTIVE-INDEX, AND ALPHA-PARAMETER IN INGAAS-GAAS SQW BROAD-AREA LASERS

Gain, refractive index, and the linewidth enhancement factor, or alpha -parameter, are measured in broad-area InGaAs-GaAs single-quantum-well semiconductor lasers using below-threshold amplified spontaneous emis sion spectra and a far-field filtering technique, The alpha parameter is shown to increase dramatically with increasing carrier density and wavelength, Modes propagating in the transparent substrate of the lase rs are shown to have a significant influence on the measured value of alpha.