BLUE-LIGHT GENERATION BY FREQUENCY DOUBLING OF A LASER DIODE IN A PERIODICALLY DOMAIN-INVERTED LITAO3 WAVE-GUIDE

We report quasi-phase matched second-harmonic generation by frequency doubling of a laser diode in LiTaO3 having a first-order periodically domain-inverted region and proton-exchanged channel waveguide. A deep domain-inverted region and a low-loss channel waveguide with strong confinement are formed by using proton-exchange and quick heat treatment techniques. Utilizing this structure, a high normalized conversion efficiency of 157%/W is obtained with a Ti:Al2O3 laser. Using a temperature-controlled laser diode and AR coating on the input and output facet of the waveguide, the laser diode maintains single-mode oscillation without any mode hopping. Consequently, 1.1 mW of blue light is obtained at a wavelength of 436.5 nm.