二维复合压电型表面波声子晶体带隙特性

设计了在镍圆柱体底部添加薄环氧树脂并沉积在铌酸锂基底的二维复合压电型声子晶体。通过有限元法计算了该结构的能带结构、分析了其带隙特性。计算结果显示:通过引入环氧树脂来减小散射体的有效弹性模量,从而降低了声表面波(SAW)完全带隙,同时打开了多条SAW方向带隙。计算了传输损失来验证带隙的存在性且讨论了其传输特性。利用布里渊区高对称点X处不同本征模态的位移场分析了带隙的形成机理。此外,还研究了共振体几何参数对SAW完全带隙、XM方向SAW带隙特性的影响,研究发现,随环氧树脂厚度的增加,在XM方向出现了一条宽为158 MHz的宽禁带。研究结果为设计基于声子晶体的电声设备提供了参考。

Surface acoustic wave bandgaps in a two-dimensional composite piezoelectric phononic crystal

A two-dimensional composite piezoelectric phononic crystal was proposed,which is composed of a thin epoxy at the bottom and a nickel pillar at the top and deposited on the lithium niobate substrate.The dispersion relation of the structure was calculated by a finite element method,the bandgap characteristics of the composite piezoelectric phononic crystal were also carefully analyzed.The results show that the effective elastic modulus of the scatterer is reduced by introducing epoxy,so that the complete band gap of the surface acoustic waves(SAWs)is reduced and multiple SAW directional band gaps are opened.The transmission spectra were calculated to verify the existence of the band gap,and its transmission characteristics were discussed.The mechanism of band gap formation was analyzed by using the displacement fields of different eigenmodes at the edge X of Brillouin zone.Furthermore,the effect of the geometric parameters of the pillar on the SAW complete band gap and XM direction SAW band gap characteristics were also studied.It is found that,as the thickness of epoxy increases,multi-band gaps in the XM direction will merge to form a wide band gap of 158 MHz.The research content provides a reference for designing of electroacoustic equipment based on phononic crystal.