Milliwatt-order blue-light generation in a periodically domain-inverted LiTaO₃ waveguide

We report the characterization of a quasi-phase-matched second-harmonic generation device in LiTaO₃ that has a periodically domain-inverted region and a proton-exchanged channel waveguide. A blue-light power of 2.4 mW was obtained at a 424-nm wavelength. The observed temperature bandwidth for FWHM power is approximately 3°C-cm, which is three times wider than that in a similar device in LiNbO₃. It is also shown that diffraction-limited focusing of the generated blue light may be obtained.