First-order quasi-phase-matched second-harmonic generation in a LiTaO(3) waveguide

We achieved improvement in conversion efficiency in a first-order quasi-phase-matched second-harmonic generation device that uses a LiTaO(3) waveguide by experimentally characterizing the device process and the performances. Efficient overlaps among propagation light modes and the first-order periodically domain-inverted region are gained in a strongly confined waveguide fabricated by use of proton exchange annealed by a quick heat treatment. A blue-light power of 22 mW is obtained for a conversion efficiency of 18% by using a Ti:Al(2)O(3) laser. The observed FWHM temperature and wavelength acceptance bandwidths for second-harmonic generation power are 2.5 °C and 0.13 nm, respectively. Using this device with antireflection coating on the input and output facets of the waveguide, we generate 1.3 mW of blue light for a conversion efficiency of 4% by direct diode-laser doubling.