Low-loss low-confinement GaAs-AlGaAs DQW laser diode with optical trap layer for high-power operation

A low-confinement asymmetric GaAs-AlGaAs double-quantum-well molecular-beam-epitaxy grown laser diode structure with optical trap layer is characterized. The value of the internal absorption coefficient is as low as 1.4 cm(-1), while keeping the series resistance at values comparable with symmetrical quantum-well gradient index structures in the same material system. Uncoated devices show COD values of 35 mW/mu m. If coated, this should scale to about 90 mW/mu m, The threshold current density is about 1000 A/cm(2) for 2-mm-long devices and a considerable part of it is probably due to recombination in the optical trap layer. Fundamental mode operation is limited to 120-180 mW for 6.5-mu m-wide ridge waveguide uncoated devices and to 200-300 mW for 13.5-mu m-wide ones, because of thermal waveguiding effects, These values are measured under pulsed conditions, 10 mu s/l ms.