Liang Yuzhang, Chu Shuwen, Wei Xinran, Wei Haonan, Cheng Sun, Han Yi, Peng Wei
School of Physics, Dalian University of Technology, Dalian 116024, China.
College of Physical Science and Technology, Dalian University, Dalian 116622, China.
Nanophotonics. 2024 Aug 2;13(21):3953-3961. doi: 10.1515/nanoph-2024-0159. eCollection 2024 Sep.
Hybridization coupling among plasmon modes is an effective approach to manipulate near-field properties thus optical spectral shapes of plasmonic nanostructures. Generally, mode hybridization coupling is achieved by modifying the topography and dimensions of nanostructures themselves, with few concerns about substrate-induced manipulation. Herein, we propose a composite nanostructure consisting of a gold (Au) nanodisk array and a thin Au film supported by a dielectric substrate. In this configuration, both the refractive index of the dielectric substrate and thin gold film's thickness mediate the interaction of plasmon modes supported by upper and lower interfaces of the composite nanostructure, resulting in two hybridized plasmon modes. We systematically investigate the relationship between optical fields at the top surface of plasmon modes before and after the hybridization coupling. Specifically, the near-field amplitude at the top surface of the unhybridized modes is stronger than that of individual hybridized mode, and lower than the near-field summation of these two hybridized modes. This work not only provides a straightforward strategy for generating two plasmon modes in a nanostructure but also elucidates the variation of the optical field during the hybridization process, which is of crucial significance for applications, such as upconversion enhancement and multi-resonance sensing.
等离子体模式之间的杂交耦合是一种操纵近场特性从而调控等离子体纳米结构光谱形状的有效方法。一般来说，模式杂交耦合是通过改变纳米结构自身的形貌和尺寸来实现的，而很少关注衬底诱导的操纵。在此，我们提出一种由金（Au）纳米盘阵列和由介电衬底支撑的薄金膜组成的复合纳米结构。在这种结构中，介电衬底的折射率和薄金膜的厚度都介导了复合纳米结构上下界面所支持的等离子体模式之间的相互作用，从而产生两种杂交等离子体模式。我们系统地研究了杂交耦合前后等离子体模式顶表面光场之间的关系。具体而言，未杂交模式顶表面的近场振幅比单个杂交模式的要强，且低于这两种杂交模式的近场总和。这项工作不仅为在纳米结构中产生两种等离子体模式提供了一种直接的策略，还阐明了杂交过程中光场的变化，这对于诸如上转换增强和多共振传感等应用具有至关重要的意义。
