Room-temperature continuous-wave operation of InGaN multiple-quantum-well laser diodes with an asymmetric waveguide structure

Room-temperature continuous-wave (cw) operation is demonstrated with InGaN multiple-quantum-well laser diodes containing an asymmetric waveguide structure. Pulsed threshold current densities as low as 5.2 kA/cm2 have been obtained for ridge-waveguide laser diodes grown on sapphire substrates by metal-organic chemical vapor deposition. For improved thermal management, the sapphire substrate was thinned and the devices were mounted p side up onto a copper heatsink. Under cw conditions at 20 °C, threshold current densities were 8.3 kA/cm2 with threshold voltages of 6.3 V. The emission wavelength was 401 nm with output powers greater than 3 mW per facet. Under cw conditions, laser oscillation was observed up to 25 °C. The room-temperature cw operation lifetimes, for a constant current, exceeded one hour.