High-power 630–640 nm GaInP/GaAlInP laser diodes

High-power visible laser diodes operating at 630–640 nm have been demonstrated. The devices have a GaInP/GaAlInP single quantum well, graded-index separate confinement heterojunction. For 100 μm broad stripe uncoated lasers, threshold current densities of 1.06 KA/cm2 and pulsed output powers as high as 1.5 W/facet (total 3 W) at room temperature were achieved by optimizing the device cavity length. By coating rear facets with high-reflectivity coatings, threshold current densities were reduced to 750 A/cm2, and output powers of 1.95 W were obtained. Unusual differential quantum efficiency versus cavity length characteristics were observed and are attributed to carriers spillover from the spacer/waveguide regions into the cladding layers.