Low-threshold GaInAsSb/AlGaAsSb quantum-well ridge-waveguide lasers emitting at 2.1 mu m

The authors report on a laser structure consisting of the following layers grown on an n-GaSb substrate by molecular beam epitaxy: n-GaSb buffer, n-AlGaAsSb cladding, active consisting of GaInAsSb wells and AlGaAsSb barriers, p-AlGaAsSb cladding, and p/sup +/-GaSb contacting. Ridges 8- mu m wide were defined by reactive ion etching. For CW operation of a 300- mu m-long device at a heat-sink temperature of 20 degrees C, the threshold current is 29 mA and the maximum power is 12.5 mW/facet limited by junction heating. Initial slope efficiency is approximately 0.1 W/A per facet. Fundamental-mode emission is maintained up to 200 mA, with lateral full width at half maximum (FWHM) of 15 degrees . For the transverse far-field pattern, the FWHM is approximately 50 degrees . The emission spectra show multiple longitudinal modes at approximately 2.13 mu m.