640-nm laser diode for small laser display

Short wavelength and highly efficient AlGaInP quantum-well laser diode is promising as a red light source for small laser display application. Two kinds of the laser diodes are presented in this paper. A narrow ridge laser diode was designed for single lateral mode. In addition, a broad area laser diode was optimized for the higher power operation. To suppress a carrier leakage from an active layer, AlInP cladding layers were adopted to both of the lasers. Evaluation tests of the fabricated lasers were performed under CW operation. The wavelength of the narrow ridge laser was 636.0 nm under the condition of 25°C and 100 mW. Single lateral mode oscillation and the high wall plug efficiency of 29% were obtained. The beam divergences were 16° and 8° in fast and slow axes, respectively. The broad area laser showed lasing wavelength of 636.9 nm at 25°C for 200 mW output. The wall plug efficiency was 30% under this condition. Both of the lasers showed both high luminance and high wall plug efficiency. These lasers are suitable for small laser display applications.