Resonant excitation of Rayleigh waves in a bicrystalline piezoelectric structure

The paper considers several situations when in bicrystalline structures with a small gap between two monoclinic piezoelectrics a surface Rayleigh wave in one of the crystals is transformed, as a result of the electromechanical interaction, into a leaky (pseudosurface) mode with a small transfer of energy into the other crystal. For symmetric orientations of the surfaces and directions of propagation, the leaky mode has, depending on the material constants, one or two leakage fluxes which differ in direction and polarization. It is shown that a perturbation of the symmetry can increase the number of leakage fluxes to four. Resonant excitation of a Rayleigh surface wave occurs when a bulk wave which increases the leakage fluxes on refection is incident on the boundary of the adjacent medium. When there are several such fluxes, it is also possible to use a number of independent incident ''pump'' waves. A change in the intensities and phases of the incident waves can be used to influence the resonant parameters. In the usual estimates of the electromechanical coupling coefficient e(2) similar to 0.1, the maximum of the Rayleigh wave excitation coefficient, defined as the ratio of its amplitude to that of the incident wave, is of the order of 1/e(2) similar to 10. The width of the resonance (in terms of the angle of incidence) is of the order of e(4) similar to 10(-2) similar to 0.5 degrees, which significantly exceeds the width of the earlier studied resonance for the excitation of Blustein-Gulyaev waves - of the order of e(6) similar to 10(-3) similar to 3'.