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 (VCL's) emitting near 850 nm, We report a low continuous-wave (CW) room-temperature threshold current of 290 mu A from top-emitting, 840-nm VCL's with a 5-mu m-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 postgrowth rapid thermal annealing (RTA) on the characteristics of AlInGaAs-AlGaAs VCL's and found that RTA improves the material quality and significantly enhances VCL performance.