Extractions of reflection and velocity parameters for surface acoustic wave in two-dimensional piezoelectric phononic crystals

Two-dimensional (2D) piezoelectric phononic crystals (PnCs) have richer properties of band gaps than 1D PnCs but not enough study on the calculation of designing parameters such as reflection and velocity. This paper proposed a model to calculate these parameters of 2D piezoelectric PnCs with finite element method (FEM). In the model, by comparing two SAW delay line structures respectively with/without PnCs and using time domain window to wipe out triple reflection, reflection and velocity can be achieved. Through an example of 2D Nickel/128°YXLiNbO₃, it shows that the transmission and reflection of 2D piezoelectric PnCs change rapidly in the frequency band, which is different from the 1D IDTs, and the velocity of the SAW in the 2D PnCs is slower than in the free surface of the piezoelectric substrate.