Propagation of Surface Acoustic Waves in Small Scale Periodic Structures

Abstract

AbstractThis chapter, as well as the next two chapters, will be devoted to the surface acoustic wave (SAW) propagation along the surface of an acoustic line with periodic systems of irregularities having the shape of etched grooves, bars of metal, etc. (Fig. 6.1). Such periodic structures placed in the way of the wave propagation are the basic elements for many SAW devices. The main reason to use the gratings is that in order to get certain performances of devices, it is necessary to be able to control the wave propagation: to reflect the wave with small losses, to change the direction of the wave propagation, to scatter the waves, to transform bulk waves into surface waves, etc. Because of the complicated structure of SAW (Chap. 1), these operations cannot, as a rule, be performed by means of a single (local) scattering element and only a large number of perturbations placed periodically (or quasi-periodically) on the acoustic line surface allow us to obtain the required control of SAW propagation. In this case the influence of each separate element on the wave propagation can be small, but in the whole their influence can be essential. The separation of functions of SAW excitation and reception (by means of interdigital transducers) and forming the device performances by using quasi-periodic reflecting structures also has certain advantages. Nowadays, resonators and dispersion delay lines with unique characteristics are designed on the base of reflecting structures.KeywordsSurface WaveRayleigh WaveSurface Acoustic WaveIsotropic BodyBulk WaveThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.