LINBO3 OPTICAL WAVE-GUIDE DEVICES

This paper describes the present status of LiNbO3 optical waveguides with respect to the optical grade crystal, growth process, de drift, and optical damage. In addition, the wideband optical modulators, QPM-SHG blue light source and epitaxial growth of LiNbO3 are reported. Optical grade crystals are needed for devices described in the foregoing and the requirements for such crystals have been proposed. The physics of optical waveguides has been understood and the relationship between the device properties and fabrication processes has been clarified. Methods to suppress the dc drift which has been one of the obstacles in practical applications of optical waveguides have been established. The solutions to minimize the optical damage in SHG devices have been found. Recently, drift-free optical modulators and wideband optical modulators for 70-GHz applications have been reported. Because of the rapid progress in polarization inversion technologies, SHG devices for blue-light emission with an output power of 20 mW and a conversion efficiency of 600 percent/Wcm(2) have been developed. Solid-state lasers formed by doping Er and Nd to crystals have been investigated. The research of growing an LiNbO3 thin film to form an optoelectrical integrated circuit has been carried out.