Research Of SAW AEO Effect

Theories of Acousto-optical (AO) effect, Electro-optical (EO) effect, and Acousto- electro-optical (AEO) effect are systematically studied. This paper concludes definitions of AO effect, diffraction efficiency, AO figure of merit and effective AO coefficient. The essay introduces classified method of AO interaction and the difference between bulk-wave and surface-wave, and also introduces the definition and category of EO effect. Two kinds of AEO devices are introduced by combining AO effect and EO effect.Coupled wave equations of surface acoustic wave (SAW) AO effect are given from basic parameter interaction equation. Direct voltage of EO effect will lead to electric momentum mismatch. Frequency of electric signal driving the electro-acoustic transducer is varying, and it will result deflection between the central frequency of device and the frequency of electric signal. Thereby the frequency deflection will lead to acoustic momentum mismatch. In the theory of Coupled wave equations of SAW AEO effect, the alone acoustic momentum mismatch is replaced by the sum of electric momentum mismatch and acoustic momentum mismatch, and coupled wave equation of AO effect is referred to as coupled wave equation of AEO effect. A formula of diffraction efficiency of the SAW AEO effect is given through solving these equations. There is an additional input end in SAW AEO device, so it can be used flexibly. The device has found applications in real time signal processing, for example correlation, convolution, match filter, spectrum analysis and optic vector calculation.Permittivity coefficientε, EO coefficientγ, elastic coefficient c, AO coefficient p and piezoelectricity coefficient e are given by using coordinate transform method, matrix transform method and subscript transform method and symmetry nature of Lithium Niobate. Those qualities can be used to calculate the modse of SAW AEO effect.By solving basic equation of SAW, AO interaction modes most suitable to AEO devices are calculated. In six cut modes of Lithium Niobate, YZ-cut and ZY-cut modes are best for AO mode. However, EO effect makes refractive index ellipsoid rotate in ZY-cut mode, and the main refractive index can't be given by finding a rotating angle. Therefore, ZY-cut mode is excluded. YZ-cut mode of AEO effect is optimal.