INFRARED MICROSCOPY STUDIES ON HIGH-POWER INGAAS-GAAS-INGAP LASERS WITH GA2O3 FACET COATINGS

InGaAs-GaAs separate confinement, heterostructure single quantum-well (SCH-SQW) lasers (lambda = 0.98 mu m) with lattice-matched InGaP cladding layers, using a new Ga2O3 low reflectivity (LR) front-facet coating, are reported. The CW peak power density (17 MW/cm(2)) of 6 mu m x 750 mu m ridge-waveguide lasers is limited by thermal rollover, and repeated cycling beyond thermal rollover produced no change in operating characteristics. The high-power temperature distribution along the active stripe has been measured by high-resolution infrared (3-5 mu m) imaging microscopy. The temperature profile acquired for a very high optical power density P-D = 11 MW/cm(2) was found to be uniform along the inner active laser stripe, and revealed a local temperature increase at the LR front facet Delta T-f of only 9 K above the average stripe temperature Delta T-s = 24 K, An excellent front-facet interface recombination velocity < 10(5) cm/s has been inferred from the measured low local temperature rise in the front facet.