Carrier nonuniformity effects on the internal efficiency of multiquantum-well lasers

We investigate quantum efficiency limitations in InGaAsP/InP multiquantum-well (MQW) laser diodes emitting at 1.5 μm. At room temperature, the internal differential efficiency above threshold is found to be reduced mainly by increasing Auger recombination and spontaneous emission within the quantum wells. These carrier loss increments are commonly assumed negligible due to MQW carrier density clamping. Even with clamped average carrier density, increasing nonuniformity of the quantum well carrier population leads to enhanced losses. We analyze these loss enhancements using an advanced laser simulation software. Excellent agreement between measurements and simulations is obtained.