Optical Gain in Lightly Doped GaAs

Measurements of both small-signal gain and stimulated emission spectra for optically pumped GaAs are described. Saturation of the amplification process is shown to play an important role in determining the spectral distribution of the stimulated emission. These measurements indicate that intrinsic gain in high-purity material does not result from band-to-band recombination and in its place an interpretation in terms of free-exciton radiative Auger recombination is suggested.