Efficient quasi-phase-matched blue second-harmonic generation in LiNbO(3) channel waveguides by a second-order grating.

We report what is to our knowledge the first efficient blue second-harmonic generation in a second-order quasi-phase-matching LiNbO(3) waveguide. Blue-light generation with a conversion efficiency of 10%/W was demonstrated. A procedure for optimizing the waveguide and the periodic domain-inversion grating has also been developed for various-order quasi-phase-matching gratings in a LiNbO(3) waveguide.