Blue-light generation by frequency doubling of a laser diode in a periodically domain-inverted LiTaO/sub 3/ waveguide

The authors report quasi-phase matched second-harmonic generation by frequency doubling of a laser diode in LiTaO/sub 3/ 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:Al/sub 2/O/sub 3/ 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.<
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