Systematics of laser operation in GaAs/AlGaAs multiquantum well heterostructures

Abstract

Important laser parameters of GaAs/AlGaAs MQWH's were measured by means of optical gain spectroscopy. Unsaturated optical net gain spectra are carefully analyzed using a model for band-to-band transitions including momentum conservation and an energy-and density-dependent lifetime broadening. The calculated dependence of the peak gain on the carrier density agrees well with experimental data. The description of energetic positions of the peak gain has to include a bandgap shrinkage with carrier density, present at laser threshold. Temperature-dependent measurements of the onset of optical net gain reveal a pure thermodynamic behavior of the absolute threshold values as a function of L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</inf> and of the characteristic temperature T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> .