Strained single-quantum-well, broadened-waveguide GaInAsSb/AlGaAsSb diode lasers have exhibited room-temperature threshold current densities as low as50 A/cm2,one of the lowest values reported for diode lasers at room temperature. These lasers, grown by molecular beam epitaxy, have emission wavelengths of∼2.05 &mgr;m,characteristic temperature of 65 K, internal quantum efficiency of 95&percent;, and internal loss coefficient of7 cm−1.Single-ended cw power of 1 W is obtained for a 100-&mgr;m aperture. ©1998 American Institute of Physics.