Finite difference time domain analysis of two-dimensional surface acoustic wave piezoelectric phononic crystals at radio frequency

The finite-difference time-domain (FDTD) method was proposed for analyzing the two-dimensional (2D) surface acoustic wave (SAW) piezoelectric phononic crystals (PCs) at radio frequency (RF),and its analysis result of the band gaps of the PCs was demonstrated through experiment.The FDTD method took into account piezoelectric effect of PCs,in which the periodic boundary conditions were used to reduce the computing cost of memory and time,and the perfectly matched layer boundary conditions were adopted as the SAW absorbers to reduce the spurious reflections.The experiments used two delay line structures with or without the piezoelectric PCs.The band gaps of the piezoelectric PCs were measured by comparing the transmission coefficients of two delay lines with a method of adding window function together.For an example of Aluminum/128° YX-LiNbO₃ piezoelectric PCs,the band gaps of the piezoelectric PCs were achieved by experiments,FDTD method and COMSOL software,which results showed that the calculated results of FDTD had a good agreement with experimental results,and is more accurate than those of COMSOL.