Second-harmonic generation of blue light in a LiTaO3 waveguide

Abstract
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.