Development of High-Efficiency Wideband Acousto-Optic Devices Using Periodic Ferroelectric Inverted Domains.

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The purpose of this research is to propose UHF ultrasonic transducers using periodic ferroelectric domains of LiNbO_3 formed by Ti-diffusion and to develop high efficiency wideband acousto-optic devices using them. The results can be summarized as follows : 1. The dependence of the domain structure on Ti Diffusion conditions was investigated, and the optimum fabrication process for the new ultrasonic transducers using periodic ferroelectric domains of LiNbO_3 was established. 2. The ultrasonic transducers were theoretically analyzed. The dependence of the characteristics on the crystal orientation, domain structure, and electrode configuration was investigated to know the optimum structure. 3. A New method for measuring the transducer characteristics precisely by fourier-transforming the 1st echo of the impulse response derived from the frequency characteristic of reflectivity was proposed. 4. The influence of the surface acoustic waves on the transducer characteristics was examined. I … More t was shown that the influence could be reduced remarkably by using non-periodic electrodes. 5. A high-efficiency wideband shear wave transducer with a conversion loss as low as 4.1dB and a specific bandwide as wide as about 90% could be obtained using 128ﾟ rotated Y-cut LiNbO_3. It was also shown that transducers optrating above 1GHz could be realized. 6. The interaction between acoustic and optical waves in LiNbO_3 was theoretically analyzed and the orientation dependence of the synthetic figure of merites was investigated. It was clarified that the isotropic optical Bragg deflector on a 36ﾟ rotated Y-cut, the anisotropic optical Bragg deflector on a 118ﾟ rotated Y-cut, and the collinear tunable optical filter on a 141ﾟ rotated Y-cut are promising configur ations. 7. The isotropic optical Bragg deflector on a 36ﾟ rotated Y-cut deflected optical beams as theoretically predicted. 8. The collinear tunable optical filter fabricated on a 128ﾟ rotated Y-cut exhibited an excellent characteristics. Less