Design of quantum well AlGaAs-GaAs stripe lasers for minimization of threshold current-application to ridge structures

The gain saturation effect and the various leakage currents related to a strip structure (spreading current, lateral diffusion current, optical cavity recombination current, and Auger recombination current) are considered. The minimum threshold current (3.3 mA) is obtained with a multiquantum-well (MQW) structure (5*80 AA) at a cavity length of 80 mu m. At these values, the lateral leakage current (spreading and lateral diffusion currents) represents about 50% of the threshold current. It is shown that for short-cavity lasers, the MQW is preferred to the SQW (single-quantum-well) structure. However, the well number in the active layer of a ridge structure is limited by the decrease of the parallel confinement and the increase of the lateral leakage current. Finally, good agreement was obtained in comparing the calculations with experimental results for GRINSCH (graded-index separate-confinement heterojunction) SQW lasers.<>