Gap acousto-electric waves in structures of arbitrary anisotropy

A theoretical study has been performed of the acousto-electric waves guided by an air gap between two identical piezoelectric crystals of arbitrary anisotropy. The permissible number of such gap waves traveling slower than all bulk modes in the structure has been established. The interdependence between the existence of these "subsonic" gap waves and surface acoustic waves on the mechanically free surface of crystals constituting the structure has been investigated. The occurrence of leaky gap waves also has been discussed. In addition, the specific features of the resonance reflection in gap structures caused by the excitation of leaky waves have been analyzed.