Properties of very-low-threshold GaAs and AlGaAs injection lasers

Fabry-Perot diode lasers with room-temperature threshold current densities in the 1500-3000 A/cm²range are described. Among the properties discussed are power and quantum efficiency, spectral characteristics, variation of threshold current density with temperature and structural factors, and reliability. Comparisons were made with available laser theory. Data concerning both catastrophic and gradual degradation will be presented. Comparative performance data will be presented for diode lasers fabricated using various heterojunction configurations. By suitable modifications of the laser fabrication process it is possible to tailor the devices for specific applications such as high peak power and high brightness or high average power but low peak power. The lowest threshold current density devices are found to be suitable mostly for the latter application because of their low threshold for catastrophic damage.