Low-threshold continuous-wave 1.5-μm GaInNAsSb lasers grown on GaAs

We present the first continuous-wave (CW) edge-emitting lasers at 1.5 μm grown on GaAs by molecular beam epitaxy (MBE). These single quantum well (QW) devices show dramatic improvement in all areas of device performance as compared to previous reports. CW output powers as high as 140 mW (both facets) were obtained from 20 μm × 2450 μm ridge-waveguide lasers possessing a threshold current density of 1.06 kA/cm², external quantum efficiency of 31%, and characteristic temperature T₀ of 139 K from 10°C-60°C. The lasing wavelength shifted 0.58 nm/K, resulting in CW laser action at 1.52 μm at 70°C. This is the first report of CW GaAs-based laser operation beyond 1.5 μm. Evidence of Auger recombination and intervalence band absorption was found over the range of operation and prevented CW operation above 70°C. Maximum CW output power was limited by insufficient thermal heatsinking; however, devices with a highly reflective (HR) coating applied to one facet produced 707 mW of pulsed output power limited by the laser driver. Similar CW output powers are expected with more sophisticated packaging and further optimization of the gain region. It is expected that such lasers will find application in next-generation optical networks as pump lasers for Raman amplifiers or doped fiber amplifiers, and could displace InP-based lasers for applications from 1.2 to 1.6 μm.