Surface acoustic waves in a two-dimensional phononic crystal slab with locally resonant units

We report that the surface acoustic waves (SAWs) in finite two-dimensional phononic crystal slab can be manipulated by the surface-stubbed bar-like locally resonant (LR) units. The absolute band gaps for SAWs (SABGs) can be opened both below the sound cone and in the band gap of bulk wave. Numerical evidence shows that, the SABGs are stemmed from the coupling between the SAWs and the local resonance of the bar-like units. The transversal or longitudinal oscillating LR mode can couple selectively to SAW when the LR bar is stubbed in a position where the displacement of the SAW is mainly in x - or y -direction. As a result, the central frequency and the width of the SABG can be adjusted by the geometric shape and the stubbed position of the LR unit, respectively.