Continuous-wave second-harmonic generation of green light in periodically poled thin-film lithium tantalate.

Thin-film lithium tantalate (TFLT) is attracting increasing attention in nonlinear generation of visible lasers due to its large second-order nonlinearity and reduced photorefractive effect. In this Letter, we design and fabricate a periodically poled TFLT waveguide for frequency doubling of a near-infrared laser operating at around 1064 nm. Continuous-wave 1.87-mW second-harmonic green light was obtained from the TFLT waveguide, and the nonlinear conversion efficiency is about 11.7%. The periodically poled TFLT waveguide exhibits a narrow wavelength acceptance bandwidth, a large nonlinear coefficient, and a stable output in the visible. The study present in this work will pave the way for the application of TFLT in nonlinear integrated photonics.