二维声子晶体多点缺陷局域模的分离特性

Splitting Characteristics of Point Defects Local Modes in 2-D Phononic Crystals

以二维铝圆柱/空气正方格子声子晶体为研究对象,利用平面波展开法结合超原胞的方法研究了点缺陷局域模的分离特性及模场分布特性。结果表明,多点缺陷引入将使局域声子因散射波之间的干涉而产生局域模的分离,且分离程度与多点缺陷所形成腔的几何形状、封闭程度以及边缘的构造有关;带隙中局域模的模场分布与它在带隙中的位置有关。点缺陷局域模的分离特性在声方向滤波器、窄带声波导方面将有很大的应用价值。

The splitting characteristics of local mode of point defects and the distribution characteristics of mode field of point defects in 2-D phononie crystal, which is composed of 2-D aluminium cylinders/air square lattices phononie crystal, have been studied by combining the plane-wave expansion and super cell method. The result indicates that the localized phononies separate the local mode because of the scatter wave interference when the point defects exist and the splitting extent of the local mode is relation to the geometric form, the edge structure and the close extent of the cave formed by point defects. The distribution of the local mode in bandgaps is relation to its position in bandgaps. The splitting characteristics of point defects local mode will be valuable in the implementations of directional sonic filters and of narrow band sonic waveguides.