Diode lasers with asymmetric waveguide and improved beam properties

Fast axis beam divergence of 1.95 μm GaSb-based diode lasers was reduced to 42°of full-width-at-half-maximum. The beam properties were improved thanks to development of efficient laser heterostructure with asymmetric waveguide. Near field was expanded almost exclusively into n-cladding by reduction in the refractive index step at the corresponding heterointeraface. The related reduction in the band offset between waveguide core and n-cladding was balanced by introduction of the thin carrier stopper layer. Multimode 100 μm wide ridge waveguide lasers demonstrated continuous wave output power of about 1.5 W at 8 A at 20°C.