AI 中文总结
本研究将特征模式分析扩展至等离子体纳米结构，构建流体动力学体积积分方程并转化为广义特征值问题，通过三种纳米结构验证，可识别其本征共振，为相关结构的分析设计提供实用工具。
AI 中文摘要
金属纳米结构可在亚波长尺度约束电磁场，使其有望作为等离子体纳米天线。在该尺度下，金属的响应呈现非局域特性，流体动力学模型被广泛用于描述这一响应。然而，现有求解器仅能输出对指定激励的响应，无法直接揭示结构的本征共振特性。本研究将特征模式分析扩展至等离子体纳米结构，以实现对其共振行为的非激励依赖模态分析。对于简单金属，耦合的流体动力学方程与体积积分方程可简化为仅含感应电流的单一流体动力学体积积分方程。该方程经离散化后，在特征模式分析框架下转化为广义特征值问题，其解可得到结构的特征模式电流及模态显著性曲线。通过三种金属纳米结构（纳米球、纳米棒、纳米二聚体）对所提框架进行验证，结果表明该方法可识别各结构的本征共振，包括特定激励源未激发的共振，以及非局域响应产生的、局域模型中不存在的额外共振。所提框架为理解等离子体纳米结构的模态机制提供了物理见解，可作为分析与设计这类结构的实用工具。
英文摘要
Metallic nanostructures confine electromagnetic fields at subwavelength scales, making them attractive as plasmonic nanoantennas. At these scales, the response of metals becomes nonlocal, and the hydrodynamic model is widely used to capture this response. However, existing solvers provide only the response to a prescribed excitation and do not directly reveal the intrinsic resonances of the structure. This work extends the characteristic mode analysis to plasmonic nanostructures to enable excitation-independent modal analysis of their resonant behavior. For simple metals, the coupled hydrodynamic and volume integral equations are reduced to a single hydrodynamic volume integral equation in terms of the induced current. The equation is discretized and cast as a generalized eigenvalue problem within the characteristic mode analysis framework, whose solution yields the characteristic mode currents and modal significance curves of the structure. The proposed framework is validated through three metallic nanostructures: a nanosphere, a nanorod, and a nanodimer. The results show that the method identifies the intrinsic resonances of each structure, including resonances not excited by a given source and additional resonances arising from the nonlocal response, which are absent in local models. The proposed framework provides physical insight into the modal mechanisms of plasmonic nanostructures and serves as a practical tool for their analysis and design.
