Second-harmonic generation of blue light in a LiTaO3 waveguide

We report blue light generation in a LiTaO3 waveguide by quasi-phase-matched (QPM) second-harmonic generation (SHG). A periodically domain-inverted structure for QPM is fabricated in LiTaO3 by proton exchange of a selective Ta-masked area using pyrophosphoric acid followed by heat treatment. By utilizing this structure and low-loss proton-exhanged waveguides, we have realized a third-order QPM-SHG device. As a result, 0.13 mW of harmonic blue light was generated for a conversion efficiency of 18%/W.