The role of electromagnetic waves in the reflection of acoustic waves in piezoelectric crystals

The role of electromagnetic effects in the reflection and transmission of acoustic waves in piezoelectric materials is discussed. Attention is focused on the analysis of a number of situations where the coefficients of plane wave conversion derived on the basis of the electromagnetic theory differ significantly from the coefficients calculated within the frame of the quasi-electrostatic approximation. This effect occurs at quasi-normal incidence for angles of the order of va/vel, where va and vel are the typical velocities of the sound and electromagnetic waves, respectively. For instance, according to the electromagnetic description, the acoustic wave must suffer total reflection while the quasi-electrostatic approximation predicts almost total transmission. The possibility of experimental observation of the above effects is also discussed.