Ridge waveguide InGaN/GaN quantum dot edge emitting visible lasers

Abstract

Blue-emitting and green-emitting laser heterostructures were grown by molecular beam epitaxy, incorporating InGaN/GaN quantum dots as the active medium, with a measured quantum efficiency of 60% on n-GaN bulk substrates. These quantum dots exhibit no S-shape in the photoluminescence peak wavelength as a function of temperature, as typically found in comparable quantum well devices. The lasers were characterized by a threshold current density, J th , of 930 A/cm 2 under pulsed bias, with a differential efficiency of 13.9%, and a wall plug (power conversion) efficiency of 0.4% at 1050 A/cm 2 . Green-emitting quantum dot lasers have J th = 935 A/cm 2 . The lasers were also characterized by their modal properties through near field imaging.