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

本研究的目的是提出一种利用钛扩散形成的铌酸锂周期性铁电畴的超高频超声换能器，并利用它们开发高效率的宽带声光器件。主要研究结果如下：1.研究了Ti扩散条件对畴结构的影响，确定了利用LiNbO_3周期性铁电畴制作新型超声换能器的最佳工艺。2.对超声换能器进行了理论分析。的晶体取向，域结构，和电极配置的特性的依赖关系进行了研究，知道最佳的结构。3.提出了一种利用反射率的频率特性对脉冲响应的一阶回波进行傅里叶变换，从而精确测量换能器特性的新方法。4.研究了声表面波对换能器特性的影响。我 ...更多信息 结果表明，采用非周期电极可以显著减小这种影响。5.采用128 °旋转Y切LiNbO_3可获得转换损耗低至4.1dB、比带宽约为90%的高效率宽带横波换能器。实验结果表明，该换能器可以实现1GHz以上的光学性能。6.本文从理论上分析了LiNbO_3晶体中声波与光波的相互作用，研究了晶体合成图形的取向关系。结果表明，在36 °旋转Y切上的各向同性光学布拉格偏转器、在118 °旋转Y切上的各向异性光学布拉格偏转器和在141 °旋转Y切上的共线可调谐光学滤波器是很有前途的结构。7.理论预测了各向同性光学布拉格偏转器对36 °旋转Y切光束的偏转。8.在128 °旋转Y切上制作的共线可调谐光学滤波器具有优良的特性。少

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