Short-wavelength (638 nm) room-temperature CW operation of InGaAlP laser diodes with quaternary active layer

638 nm room temperature (25°C) CW operation was successfully achieved by InGaAlP visible light laser diodes with a quaternary active layer. A transverse mode stabilised selectively buried ridge-waveguide structure was fabricated by metalorganic chemical vapour deposition. The threshold current was 100 mA at 25°C and CW operation was attained at up to 50°C. The oscillation wavelength was the shortest for room temperature CW operations of laser diodes ever reported.