Gain and carrier lifetime measurements in AlGaAs multiquantum well lasers

Gain and carrier lifetime have been measured at threshold in shallow proton stripe AlGaAs multiquantum well lasers with several different active layer structures. The gain is found to vary linearly with injection as in conventional double heterostructure lasers. The slope of the gain current curve and the carrier lifetime at threshold decrease slightly with temperature, suggesting the absence of a large temperature-dependent nonradiative mechanism in these lasers. The carrier density at threshold in low-threshold modified multiquantum well lasers is a factor of four lower than in similar single-quantum well lasers. Thus, the effect of a nonradiative mechanism which varies superlinearly with the injected carrier density is considerably reduced in modified multiquantum well lasers. This may allow the fabrication of low-threshold lasers in InGaAsP/InP that will have a lower temperature dependence of the threshold.