Full band gaps for surface acoustic waves in piezoelectric phononic crystals

Surface acoustic waves in phononic crystals consisting of holes in a Y-cut lithium niobate substrate are identified numerically using a plane-wave-expansion method. The phononic crystal has a square lattice with circular void inclusions with a filling fraction of 63%. It is found that a large full-band gap with a fractional bandwidth of 34% exists for surface acoustic waves of any polarization and incidence. coincidentally with the full band gap for bulk waves propagating in the plane of the surface.