Strictly speaking, surface acoustic wave generally refers to various modes of waves propagating along the surface or interface. Different boundary conditions and propagation medium conditions can excite different modes of surface acoustic waves. There are Rayleigh waves, leaky waves, generalized Rayleigh waves and horizontal shear waves (SH. Saw), electro-acoustic wave (B. G wave), lamb wave, etc. There are Love Wave, Sisavat Wave, stoneley wave, etc. On a substrate with a layered structure.
As early as more than ninety years ago, people studied this kind of wave. 1885, based on the study of seismic waves, Rayleigh theoretically expounded the characteristics of elastic waves on isotropic solid surfaces. However, due to the limitation of science and technology at that time, this kind of surface acoustic wave has not been applied in practice. Until the sixties, due to the development of semiconductor plane technology and laser technology, a large number of artificial piezoelectric materials appeared, which provided the necessary material and technical basis for the development of surface acoustic wave technology.
As a new science and technology developed in the late 1960 s, it is a frontier subject combining acoustics and electronics. Because the propagation speed of surface acoustic wave is100000 times slower than that of electromagnetic wave, and it is easy to sample and process on its propagation path, it is possible to realize miniaturization and multifunction of electronic devices by using surface acoustic wave to simulate various functions of electrons. At the same time, surface acoustic wave devices provide signal processing functions in VHF and UHF bands in a very simple way, so surface acoustic wave technology has been widely used in radar, communication and electronic countermeasures. The application of surface acoustic wave was first used as a frequency stabilizing filter in military radar, radio and television fields.
1949, lithium niobate single crystal was discovered in Bell Telephone Laboratory. 1964, the patent of planar structure transducer for exciting surface acoustic wave was published. In particular, in 1965, R. M.white and F.W.voltmer published a paper entitled "A New Type of SAW-Electrical Transducer-Interdigital Transducer" in the Journal of Applied Physics, thus achieving a key breakthrough in SAW technology.