Study On Propagation Characteristics Of Acoustic Wave In SAW Devices

As a new type of electronic device, SAW (surface acoustic wave) devices have been well developed in both scientific research and practical application fields in recent years. There are many types of SAW devices. They mainly include SAW filters, wireless sensing devices, resonantors, delay cables, matching filters, generators, SAW convolvers and so on. In recent years, SAW devices have been extensively applied in present wireless communication field, optical fiber communication network, aerial traffic control, electronic warfare, nondestructive examination, sonar, and television technique for their merits of minitype, high reliability, good consistency, multifunction, flexibility of design and so on.The fabrication of SAW devices can not be apart from the study of the propagation characteristics of SAW in piezoelectric materials that are used in the devices. Some work about it is done in this paper. Because the use of film material is an important development direction of the devices, so the propagation characteristics of SAW in multilayers are selected as the study content. The basic theory of SAW propagation in multilayers is introduced in the first chapter. In the second chapter, the theory introduced in the last chapter is used to study the SAW properties in LiNbO₃ andα-SiO2 which are typical piezoelectric materials used in SAW devices. The SAW characteristics in LiNbO₃ substrates deposited film of metal, Si orα-SiO2 are studied too. In the third chapter, the propagation characteristics of SAW in several multilayers are studied and the new type acoustical waveguides using the knowledge about it are designed. The research on SAW property in multilayers which conclude slow acoustic and fast acoustic two layers is done too. In the forth chapter, the new design of mode converter which is the key element of integrated optical acoustooptic tunable filter (AOTF) is given based on the calculation result.