Energy conversion in piezoelectric superlattices

A superlattice is formed in a piezoelectric substrate by intervallic polarizing oppositely along one direction. Wave propagation in this structure is studied with plane-wave expansion method. The polariton behavior in the superlattice is obtained by solving Newton's equations of motion and Maxwell's equations simultaneously. Significant coupling between mechanical and electromagnetic energy occurs in the vicinity of the center of the first Brillouin zone. At the frequency bands of strong coupling, part of the excitation electromagnetic energy will convert into mechanical energy in the superlattice or radiating into free space as EM waves. By measuring the S parameters, the coupling behavior is observed and the frequency bands corresponding to different kinds of energy conversion can be identified.