二维声表面波压电声子晶体在射频段的时域有限差分法

对二维声表面波压电声子晶体在射频段的带隙特性,进行了时域有限差分法(FDTD)理论推导和计算,并提出实验方法对比验证。FDTD计算模型考虑了压电效应,引入周期边界条件以节省计算空间和时间,采用完全匹配层以解决声表面波在截断边界处的虚拟反射问题。实验上分别设计有/无二维压电声子晶体的两种宽频带延迟线结构,测量两种延迟线的传输系数取差值,得到了二维压电声子晶体的带隙;其中通过时域加窗函数保留一次传输信号,进行干扰信号的去除。以铝/128°YX-LiNbO3二维压电声子晶体为例,该FDTD方法、商业有限元软件COMSOL、实验方法均得到了100⁵00 MHz射频段内的多个带隙,三种带隙对比证明了FDTD计算带隙与实验测量带隙一致,比COMSOL计算的计算带隙精度更高。

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.