Influence of mirror reflectivity on laser performance of very-low-threshold vertical-cavity surface-emitting lasers

The influeuce of mirror reflectivity on laser performance of InGaAs-GaAs vertical-cavity surface-emitting lasers fabricated by selective oxidation is investigated by the stepwise change of the number of pairs in top mirror stack after device fabrication. Devices with 18-pair stacks in the top mirror, which is the optimized number of pairs in this structure, show an output power over 1.9 mW and a slope efficiency of 55% while maintaining a low threshold current of 212 μA. The analysis of the threshold current and differential efficiency related to mirror reflectivity shows an internal quantum efficiency of 95%, an internal round-trip loss of 0.072, and a transparency current density of 71 A/cm
²
.