Theory And Experimental Studies On ZnO Thin Film And IDT Using Optic Waveguide Phase Modulator Driven By A SAW

"Theory and experimental studies on ZnO thin film and IDT using opticwaveguide phase modulator driven by a SAW" is the sub-project of "Theoretical andexperimental research on photo-electronic integrated acceleration Seismic Geophone"supported by Natural Science Foundation of China.photo-electronic integrated acceleration Seismic Geophone is a kind of sensor。The polarizer,optic waveguide,phase modulator,PIN and signal processing circuithave been integrated on the same substrate using the technology integrated optics andsemiconductor., A kind of novel optic waveguide phase modulator driven by a surfaceacoustic wave(SAW), applied to the signal modulation of photo-electronic-integratedaccelerator using acoustooptic interaction, has been presented in this dissertation. Thismodulator can offer several advantages: ripe preparation technology, high operatingfrequency, long interaction distance, high energy density, small bulk andeasy-integrated, and create a new thinking for the modulation of integrated optics.Staring with the theory of photo-electronic integrated acceleratetion sensor, therelation between stress-strain and acceleration is addressed, and hence does therelation and the phase change;then the theory of the modulation is analyzed. Theprompting and the transfers of the SAW have been researched, and the basic theory ofthe acoustooptic modulation and acoustooptic interaction is analyzed deeply. Throughstudying the theory of acoustooptic modulating in detail, we design the ZnO thin film'and IDT' structure and fabrication parameter. And we get the optimization bybalancing the thickness of the thin film and the frequency of the SAW,the frequencyof the SAW and the conversion loss,the frequency of the SAW and the electrodeaperture width,the IDT pairs and the area of the thin film. The main designparameters of the modulator is as following: the ZnO thin film with the dimensions of5mm×0.8mm×0.003mm;IDT with the fingers of 17 pairs, the SAW frequency off₀=48MHz, the electrode aperture width of L₀=4.46mm and interdigital periodl =27.19μm .Every technological link which fabricates the ZnO thin film and IDT is discussedin detail, and great deals of experimentation have been done and the optimalparameters of arts have been found. Then we make a series of test including of theobserving of the microstructure,the fine measure of the film thickness,the directionof the crystal axes. The experimental results are quite satisfactory: the high qualityZnO thin film was developed. Being a fine qusi-single crystal thin film, it isabsolutely C-axis oriented and has many good characteristics, such as highcompactness and excellent surface smoothness. As a result, the IDT we obtained isgood in terms of smoothness, flatness and surface features. It is probable to fabricatesteady frequency properties, low propagation loss, low conversion loss and excellentcapability SAW devices.