Switchable Frequency Gaps in Piezoelectric Phononic Crystal Slabs

Abstract

A numerical study of switchable frequency band gaps in two-dimensional phononic crystal (PnC) slabs consisting of piezoelectric inclusions in an isotropic matrix is presented. Instead of changing the geometry or orientation of the PnC units or inclusions, electrical boundary conditions are used to actively control the frequency band gaps. The electrical open and short boundary conditions are considered in this paper. With different electrical boundary conditions imposed on the surfaces of the piezoelectric inclusions, the dispersion relations can be modulated and the band gaps can be switched. The validity of switchable transmission and the dependence of its characteristics on the incident slab wave modes and electrical boundary conditions are investigated as well. Using the switchable frequency gaps, switchable linear PnC slab waveguides, which show the confined propagation of slab waves, are demonstrated. As a result, the confined wave energy flows can be switched on/off by changing the imposed electrical boundary conditions. The methodology presented here enables designing PnC structures of active controlled transmission, guiding, switching, and emission for slab waves.