Low-threshold 840-nm laterally oxidized vertical-cavity lasers using AlInGaAs-AlGaAs strained active layers

We explore the use of a novel strained AlInGaAs-AlGaAs material system to achieve low-threshold current in oxide-apertured vertical-cavity lasers (VCLs) emitting near 850 nm. We report a low continuous-wave (CW) room-temperature threshold current of 290 μA from top-emitting, 840-nm VCLs with a 5-μm-wide thin-oxide aperture. The low-threshold current has been attributed to the use of strained active layers, which increase the gain and reduce the transparency current. We also studied the effects of post-growth rapid thermal annealing (RTA) on the characteristics of AlInGaAs-AlGaAs VCLs and found that RTA improves the material quality and significantly enhances VCL performance.