Low-threshold-current-density vertical-cavity surface-emitting AlGaAs/GaAs diode lasers

The optimization of electrically pumped vertical-cavity surface emitters (VCSEs) with conductive semiconductor-stack rear reflectors and mirror-reflectivity products of 0.93 for minimum threshold current density, J/sub th/, is presented. Devices of two different active layer thicknesses are fabricated: 3 mu m, as for conventional devices, and 0.6 mu m, which, according to theoretical calculations, provides J/sub th/ for lasers with a mirror reflectivity product in the 0.90-0.95 range. For structures of 0.16- mu m thick active layers, J/sub th/ values as low as 10 kA/cm/sup 2/ are obtained, in good agreement with theory. Analysis shows that for active layer thicknesses >