Second-harmonic generation in a LiTaO3 waveguide domain-inverted by proton exchange and masked heat treatment

Abstract

Second-harmonic generation in the proton-exchanged LiTaO3 waveguide is greatly enhanced by reducing the amount of proton exchange in fabricating the domain grating and the waveguide. To reduce the amount of proton exchange, a Ta-SiO2 mask is used for the periodic domain inversion and a SiO2 mask for the proton-exchanged waveguide. The fabricated device generates second-harmonic blue light of 1 mW at 429 nm with the fundamental wave power of 10.3 mW. Its normalized efficiency is 1500 %/Wcm2, which is the highest value for LiTaO3 waveguide devices reported to date.