Periodically domain-inverted LiNbO3 for waveguide quasi-phase matched nonlinear optic wavelength conversion devices

The authors’ work on LiNbO₃ waveguide quasi-phase matched nonlinear optic wavelength conversion devices is reviewed. The requirements of domain-inverted gratings for efficient wavelength conversions are shown by theoretical analysis of the device performances. The fabrication apparatus of the domain-inverted gratings is described, and it is shown that the fabricated gratings satisfy the requirements. A variety of LiNbO₃ waveguide quasi-phase matched (QPM) wavelength conversion devices were fabricated and examined. Second-harmonic green/blue/ultraviolet light generation with normalized conversion efficiencies of ∼ 100%/W, third-harmonic generation by cascading second-harmonic generation and sum-frequency generation, and difference-frequency generation for wavelength conversion in infrared wavelength range are demonstrated.