Over 1 W record-peak-power operation of a 338 nm AlGaN multiple-quantum-well laser diode on a GaN substrate

We have demonstrated the high-peak-power operation of an AlGaN-based ultraviolet laser diode (UV-LD) with a lasing wavelength of 338.6 nm. The UV-LD structure was fabricated on a bulk GaN(0001) substrate. The broad-area and vertical conductive structure of the UV-LD, whose ridge width and cavity length were 50 and 600 µm, respectively, was employed. The threshold current density and differential external quantum efficiency were estimated to be 38.9 kA/cm2 and 8.5%, respectively. The characteristic temperature of threshold current was estimated to be 119 K, and the temperature dependence of lasing wavelength was obtained to be 0.033 nm K−1. A peak power of over 1 W has been achieved in 338.6 nm under pulsed operation at room temperature, which is the highest peak power ever obtained for AlGaN-based UV-LDs.