Electroacoustic shear waves in the hollow structure of two piezoelectrics

The results of papers are presented in which dispersion properties of electroacoustic waves in the gap structure of two different piezoelectrics are considered. In particular, it is shown that in the presence of a difference of shear wave velocities in piezoelectrics there are no purely symmetric and antisymmetric modes, and the coefficients of the boundary localization of the shear wave will be significantly different. It is established that at a certain equal level of loss and gain (PT is a symmetrical structure) of two identical piezoelectrics of symmetry class 6, the symmetric and antisymmetric modes intersect. The intersection point defines an exceptional point of the PT-symmetric structure. Taking into account the unequal level of loss and gain in piezoelectrics results in either intersection, touching, or convergence of two modes at the point of their degeneracy (exceptional point) in the shear wave spectrum. As in the case of a purely PT-symmetric structure, the frequency dependence of the amplitude at an exceptional point of a quasi PT-symmetric structure (with a rather small difference in loss and gain levels) exhibits a very narrow peak, which opens up the possibility of creating hypersensitive sensors based on them.