V形-蝴蝶结孔径透射性质的数值研究

Metallic nanoaperture is the most basic structure for excitating surface plasmons and manipulating the electromagnetic energy at nanoscale. Research on transmission property of metallic nanoaperture is of great scientific significance and practical value for the development of nanolithography and nano data-storage. Compared with the conventional square or circle holes, a bowtie-shaped metallic nanoaperture has already demonstrated its capability in nanoscale constraint and energy enhancement of the electromagnetic field. However，It is still difficult to obtain a transmission spot less than 20 nm with intensive electromagnetic energy in current experiments. To solve this problem, we innovatively propose a new V-shaped–bowtie aperture. The structure combines the advantages of V-shaped and bowtie aperture in nanoscale constraint and energy enhancement of electromagnetic field. The main task of this project is to carry out the numerical study of the V-shaped–bowtie aperture; to understand the physical mechanism of interaction between the two different surface plasmon modes of the V-shaped–bowtie aperture; to optimize the V-shaped–bowtie aperture; and to obtain an intensive transmission spot with resolution less than 10nm in theory. The investigation may provide a valuable theoretical guidance and basis for experiments in high-resolution plasmonic devices design based on metallic nanoaperture.

金属纳米孔径是产生表面等离子体激元、实现纳米尺度电磁能量操纵的最基本结构。开展金属纳米孔径透射性质的研究对纳米刻蚀和纳米存储技术的发展具有重要的科学意义和实用价值。与普通的方孔或者圆孔相比，蝴蝶结形金属纳米孔径在电磁场的纳米约束和能量增强方面更具优势。但是，实验上利用蝴蝶结形孔径仍难以获得尺寸小于20nm的高强度透射斑。针对该问题，申请人结合V形和蝴蝶结孔两种结构在电磁场纳米约束和能量增强方面的优势，提出一种新的V形-蝴蝶结孔复合结构。本项目的主要任务是开展V形-蝴蝶结孔的透射性质的数值研究，明确V形-蝴蝶结孔径结构中两种不同的表面等离子体激元模式之间相互作用的物理机理，完成V形-蝴蝶结孔结构的优化设计，理论上获得分辨率低于10nm的强电磁场能量透射斑，为实验中基于孔径结构的高分辨等离子体激元器件设计提供有价值的理论依据。

本项目的主要研究目标是开展V形-蝴蝶结孔的透射性质的数值研究，明确V形-蝴蝶结孔径结构中两种不同的表面等离子体激元模式之间相互作用的物理机理，完成V形-蝴蝶结孔结构的优化设计，理论上获得分辨率低于10nm的强电磁场能量透射斑。项目实施以来，围绕申请书中提出的几项主要研究内容，对V形-蝴蝶结孔透射性质进行了深入研究，研究结果显示该V形-蝴蝶结孔径结构在可见光区主要有三个透射峰，此三个透射峰形成的物理原因分别是入射面的偶极共振、入射面的四极共振及入射面的偶极共振和V形槽的通道等离激元的类法布里波罗共振共同作用。通过对V形-蝴蝶结孔参数的优化，在三个透射峰处，均得到了10nm*8nm的透射斑，并且透射斑的最大电场强度分别是入射电场强度的176、70和196倍。完成了本项目提出的研究目标，理论上获得分辨率低于10nm的强电场能量透射斑。在此基础上，我们对研究范围进行了一定的拓展，如研究天线/缓冲层/孔径系统的偏振选择透射现象、非对称椭圆孔径阵列的Fano反射、基于等离激元V形槽和银粒子薄膜的表面增强拉曼基底等。本项目的研究成果为纳米光刻光存储、表面等离激元器件设计、表面增强拉曼光谱等应用提供了有价值的理论和实验依据。