Design and Fabrication of Acousto-optic Waveguide Phase Modulator in Electro-optic Integrated Accelerometer

摘要

A novel electro-optic integrated acceleration seismic geophone is presented in this paper. In order to modulate the phase of optical waveguide M-Z interferometer on silicon substrate, the method of acousto-optic phase modulation is proposed. The acousto-optic phase modulator realizes phase modulation by passing the reference beam through a surface acoustic wave (SAW) generated on a ZnO thin-film transducer driven by an interdigital transducer (IDT). The motivation and the transmission of the SAW is researched and the principle of IDT is discussed. The refractive index change, generated by the SAW is analyzed. On the basis of above analysis of acousto-optic phase modulation, considering the design demands of the electro-optic integrated acceleration seismic geophone, optimum dimension parameters of the acousto-optic modulation device, e.g., the number N of finger pairs, characteristic length L and interdigital period M is implemented. So optimization structure design of the ZnO thin film and the structure of IDT are designed. Lots of theoretical and experimental researches on preparation handicraft of ZnO thin film and IDT have been done and the acousto-optic phase modulator is fabricated.