Piezoelectric superlattice: From piezoelectric to Huang-Kun-like equations

The piezoelectric superlattice (PSL) consisting of periodically inverted ferro- electric domains is a special kind of artificially microstructured material. Similar to the ionic crystals, the strong coupling between the electromagnetic wave and superlattice vibration of PSL may generate the phonon polariton. In this paper, by starting with the piezoelectric equations and classic motion equation, the gap between the artificial and classic lattices has been bridged, where a set of Huang-Kun (HK)-like equations were established and can be shared by both systems. Our results also show that the coupling between the photon and longitudinal “optical” phonon, which is not present in a real crystal, is dominated by the HK-like equations. The connection between the two seemingly different systems suggests that they are governed by a common physics.