Excitonic effects in gain and index in GaAlAs quantum well lasers

Abstract

Spontaneous emission and gain measurements in GaAlAs single quantum well lasers are presented. The gain is derived from the spontaneous emission detected through an opening in the top metallic contact of the lasers. Excitonic effects are seen in the gain (absorption) spectra for low carrier densities, and the step-like nature of the two-dimensional density of states is evident. From the gain spectra, refractive index changes are derived via a Kramers–Kronig transformation, and this is used to evaluate the linewidth enhancement factor as a function of photon energy.