Study of surface acoustic waves in SiO2/LiNbO3 layered-structure phononic crystals

Phononic crystal (PnC) in half-space allows anisotropic propagation and band gaps for surface acoustic wave (SAW) and promise applications such as filters and reflectors. For the feasible MEMS fabrication, a PnC comprised of cylindrical holes in a SiO2 layer covering a LiNbO3 substrate was proposed and analyzed numerically. Dispersion curves of SAWs in the PnC were calculated by using finite element method and then the band gap range for SAW was indicated. The variation of band gaps by modifying the layer thickness and cylinder size was reported. Simulation shows that SAW propagation could be stopped by thirty rows of PnCs. Then reflective gratings and resonant cavities for SAW were designed accordingly. The result showed feasibility of applying PnC in acoustic electronics devices.