Noncritical quasi-phase-matched second harmonic generation in an annealed proton-exchanged LiNbO/sub 3/ waveguide

We report the demonstration of dimensional noncritical phase matching, a phase-matched interaction length exceeding 10 mm, and an internal conversion efficiency of 204%/W for second harmonic generation of 976 nm radiation in a periodically poled, annealed proton-exchanged LiNbO/sub 3/ waveguide. Using models for the linear and nonlinear optical properties of annealed proton-exchanged LiNbO/sub 3/ waveguides and the observed ferroelectric domain grating, the phase-matching wavelength was predicted to within several nm and the conversion efficiency to within /spl ap/20% of the measured values. Optimization of waveguide second harmonic generation devices is discussed.<
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