Strained-layer AlIGaAs-AlGaAs graded-index separate-confinement heterostructure single-quantum-well diode lasers with cavity width and length of 500 and 1000-mu-m, respectively, have been operated CW at heatsink temperatures up to 125-degrees-C, with output power up to 4.9 W per facet and power efficiency as high as 49% measured at 10-degrees-C. Promising results have been obtained in initial reliability tests on uncoated devices at heatsink temperatures of 10 and 50-degrees-C.