Comparative Analysis of the Near‐ and Far‐Field Optical Response of Thin Plasmonic Nanostructures
Comparative Analysis of the Near‐ and Far‐Field Optical Response of Thin Plasmonic Nanostructures
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DOI：
10.1002/adom.202102550
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发表时间：
2022-03
影响因子：
9
通讯作者：
Lauren Zundel;Paul Gieri;S. Sanders;A. Manjavacas
中科院分区：
文献类型：
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作者：
Lauren Zundel;Paul Gieri;S. Sanders;A. Manjavacas
由金属材料制成的纳米结构支持其传导电子的集体振荡，通常称为表面等离子体。这些模式的特性由纳米结构的材料和形态决定，它们与光强烈耦合，并将其限制在亚波长体积内。特别令人感兴趣的是金属纳米结构，其尺寸沿着一个维度接近纳米甚至亚纳米尺度，因为这样的形态可以导致比常规三维纳米结构更强的光-物质相互作用和更高程度的限制。在这里，不同的厚度和纵横比的金属纳米盘的等离子体响应的远场和近场激发条件下进行了研究。据发现，对于远场激发，纳米盘的等离子体激元响应的强度随着其厚度而增加，正如从系统中传导电子数量的增加所预期的那样。然而，对于近场激发，等离子体响应随着纳米盘的厚度减小而变得更强。这种行为归因于近场源耦合到由更薄的纳米盘支撑的等离子体激元的更高效率。这项工作的结果推进了对薄金属纳米结构的等离子体响应的理解，从而增加了它们开发新应用的潜力。
Nanostructures made of metallic materials support collective oscillations of their conduction electrons, commonly known as surface plasmons. These modes, whose characteristics are determined by the material and morphology of the nanostructure, couple strongly to light and confine it into subwavelength volumes. Of particular interest are metallic nanostructures for which the size along one dimension approaches the nanometer or even the subnanometer scale, since such morphologies can lead to stronger light–matter interactions and higher degrees of confinement than regular three‐dimensional nanostructures. Here, the plasmonic response of metallic nanodisks of varying thicknesses and aspect ratios is investigated under far‐ and near‐field excitation conditions. It is found that, for far‐field excitation, the strength of the plasmonic response of the nanodisk increases with its thickness, as expected from the increase in the number of conduction electrons in the system. However, for near‐field excitation, the plasmonic response becomes stronger as the thickness of the nanodisk is reduced. This behavior is attributed to the higher efficiency with which a near‐field source couples to the plasmons supported by thinner nanodisks. The results of this work advance the understanding of the plasmonic response of thin metallic nanostructures, thus increasing their potential for the development of novel applications.