Hierarchical Plasmon Resonances in Fractal Structures
Hierarchical Plasmon Resonances in Fractal Structures
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DOI：
10.1021/acsphotonics.0c00110
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发表时间：
2020-05-20
期刊：
影响因子：
7
通讯作者：
Botton, Gianluigi A.
中科院分区：
文献类型：
--
作者：
Bicket, Isobel C.;Bellido, Edson P.;Botton, Gianluigi A.
一个等边三角形的棱柱是用来作为基本的积木，构建添加剂Sierpinski分形，使新的表面等离子体共振（SPR）在前三代的Sierpinski三角形，以及拓扑中间代之间。使用电子能量损失谱并结合本征模计算和光学有限差分时域模拟来表征这些模式。复杂的分形几何呈现出一种可预测的新共振层次，每一种共振都来自于上一代用于构建分形的构建块。中间结构打破了等边分形的偏振简并，同时保持了丰富的多波段光谱响应。分形的窄导电通道中的工程缺陷允许进一步操纵SPR响应，强调最低能量峰上的高阶SPR模式。所获得的知识用于开发更复杂的基于分形的结构的工程响应的指导方针，包括光谱响应和热点分布。
An equilateral triangular prism is used as the fundamental building block to construct additive Sierpinski fractals, enabling new surface plasmon resonances (SPR) in the first three generations of Sierpinski triangles, as well as topological intermediaries between generations. The modes are characterized using electron energy loss spectroscopy accompanied by eigenmode calculations and optical finite-difference time-domain simulations. The complex fractal geometries present a predictable hierarchy of new resonances, each arising from the previous generational building blocks used to construct the fractal. Intermediate structures break the polarization degeneracy of the equilateral fractals while maintaining a rich multiband spectral response. Engineering defects in the narrow conductive channels of the fractal allows further manipulation of the SPR response, emphasizing higher order SPR modes over the lowest energy peak. The knowledge gained is used to develop guidelines for engineering the response of more complex fractal-based structures, including the spectral response and hotspot distribution.