Abstract: A plasmonic lens based on a thin conical dielectric film adhered to a metallic disk is proposed. The structure converges normal incident light into a circular focal stripe. The circular focal stripe decreases in size with the decreasing of the thickness of the dielectric film, and converges into a focal spot when the thickness is smaller than a critical value. Moreover, the enhancement of the local field can also be improved by using the structure.

Key words: surface plasmon polarition (SPP), plasmonic lens (PL), finite-difference time-domain (FDTD), local field enhancement (LFE)

摘要： 提出一种由金属圆盘和圆锥形介质薄膜组成的表面等离激元透镜结构, 该结构能将正入射的电磁波汇聚成束缚于介质表面的圆弧形聚焦斑。这些聚焦斑的尺寸随着介质薄膜中心厚度的减小而减小, 并在薄膜厚度等于某个值时汇聚成一个焦点。该结构还能实现较好的局域场增强。

关键词: 表面等离激元, 表面等离激元透镜, 有限时域差分, 局域场增强