Propagation of surface acoustic wave in one-dimensional piezoelectric phononic crystals

We analyze the propagation of Rayleigh surface acoustic waves in one dimensional piezoelectric phononic crystals covered with an elastic film. A complete surface acoustic wave band gap is calculated by means of the plane wave expansion method (PWE) and finite element method (FEM). We focus on the effects of the geometric dimensions including the thickness of the film and the filling fraction of the phononic crystal to the band gap. We can find the width of the band gap becomes small with the increase of the thickness of covered film, and the maximum band-gap width appears when the filling fraction is 0.45.