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 cm with symmetrical quantum-well gradient index structures in the same material system. Uncoated devices show COD values of 35 mW/µm. If coated, this should scale to about 90 mW/µm. The threshold current density is about 1000 A/cm2 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-µm-wide ridge waveguide uncoated devices and to 200-300 mW for 13.5-µm-wide ones, because of thermal waveguiding effects. These values are measured under pulsed conditions, 10 µs/l m