Analyzing bull’s eye structures by a vertical mode expansion method with rotational symmetry
Analyzing bull’s eye structures by a vertical mode expansion method with rotational symmetry
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通过旋转对称的垂直模式展开方法分析牛眼结构
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Y. Lu
中科院分区：
文献类型：
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作者：
Xun Lu;Y. Lu
牛眼结构是一种金属薄膜，它有一个圆形的亚波长孔径，周围有同心的环形凹槽。它是实现超常光传输现象应用的重要结构。在绕垂直于薄膜的中心轴旋转时，结构是不变的。本文发展了一种有效的数值方法，用于分析由不同环形区域组成的材料性能为一维的靶心和其他结构。该方法是最近发展起来的垂直模态展开方法的一种新变体，它将一维特征模态中的场展开与求解标量二维亥姆霍兹方程的各种技术相结合。该方法通过分别求解不同的傅里叶分量来利用旋转对称性。对于正入射波，该方法特别有效，因为只需要求解一个傅里叶模式。应用该方法对不同形状的靶心结构进行了分析。特别是，我们发现具有22个沟槽的牛眼结构的归一化透射系数可以大于52。
A bull’s eye structure is a metallic film with a circular subwavelength aperture surrounded by concentric annular grooves. It is an important structure for realizing applications of the extraordinary optical transmission phenomenon. The structure is invariant under rotations about the central axis perpendicular to the film. In this paper, an efficient numerical method is developed for analyzing bull’s eye and other structures that consist of different annular regions where the material properties are one-dimensional. The method is a new variant of the recently developed vertical mode expansion method which combines field expansions in one-dimensional eigenmodes with various techniques for solving scalar two-dimensional Helmholtz equations. The method exploits the rotational symmetry by solving the different Fourier components separately. For normal incident waves, the method is particularly efficient, since it is only necessary to solve one Fourier mode. The method is used to analyze bull’s eye structures with different configurations. In particular, we found that the normalized transmission coefficient can be larger than 52 for a bull’s eye structure with 22 grooves.