High-performance laser diodes with emission wavelengths above 1100 nm and very small vertical divergence of the far field

The effect of variations in the vertical structure on the performance of AlGaAs-GaAs laser diodes with an InGaAs quantum well (QW) emitting around 1120 nm was investigated. With very thick waveguide layers, more than 95% of the output power is enclosed in an angle smaller than 35/spl deg/. This allows the use of fast axis collimators with a small numerical aperture. Broad area laser diodes with 100-μm stripe width, an optimized doping profile, and a double QW emit more than 12 W and show reliable operation at 5 W.