Recent progress in high-power blue-violet lasers

GaN-based 400-nm high-power lasers have been developed as a light source for optical disk recording, laser printer, and displays. The lasers in systems for optical disks with capacities greater than 50 GB are required to operate at high output power exceeding 100 mW in order to write information to a dual-layer disk. To satisfy this performance requirement, we examined the absorption loss in Mg-doped GaN super-lattice layers, and successfully reduced the internal loss by isolating these layers from the active layer.