空间非局域效应会导致具有极小特征尺寸的金属纳米结构产生非经典光学响应，是设计量子表面等离激元器件时必须考虑的因素。由于缺乏对空间非局域效应与电荷空间分布特征之间内在关联性的系统研究，已有单空隙纳腔的研究结果不能全面描述空间非局域效应对具有多空隙、多模式耦合系统光学响应的影响机理。本项目提出对金属薄膜耦合二聚体等离激元纳腔中的空间非局域效应展开理论和实验研究，目的在于阐明空间非局域效应如何依赖于感应电荷的局域密度、空间分布对称性、及有效作用面积等特征。围绕此目标，项目将探讨纳腔中不同区域空隙尺寸和颗粒错位程度对空间非局域效应的影响，以及不同共振模式的空间非局域效应。理论和计算方面，拟采用流体动力学模型和Feibelman参数非经典边界条件模型；实验方面，基于暗场光学显微成像系统进行近、远场光学响应表征。项目成果不仅具有重要的基础科学意义，而且将为功能性量子纳米光子学器件的设计提供有益参考。

Spatial nonlocality can result in non-classical optical responses in metal nanostructures with extremely small feature sizes, and thus it is one of the necessary factors needs to be considered when designing quantum plasmonic devices. Previous studies have paid little attention on the inherent relationship between nonlocal effects and the characteristics of spatial distributions of induced surface charges. As a result, conclusions drawn from single-gap plasmonic nanocavities cannot be applied to fully interpret the impacts of spatial nonlocality on the optical responses of coupled plasmonic nanostrucutres that have multiple tiny gaps and hybridized plasmon modes. This project proposes to study theoretically and experimentally the nonlocal effect in a dimer-on-film plasmonic nanocavity, aiming to disclose how spatial nonlocaity depends on the characteristics spatial distributions of induced surface charges, including localized surface charge densities, symmetry of their spatial distributions, and effective interaction areas. Around this target, influences of gap sizes in different areas and offset between particles on spatial nonlocality, and the nonlocal effects of different modes will be discussed in this project. The hydrodynamic model and Feibelman parameters related non-classical boundaries will be used for theoretical analysis and numerical calculations. Experimentally, near- and far-field optical responses of the dimer-on-film nanocavities will be characterized by a dark-field scattering imaging and spectroscopy system. Results of this project are not only significantly important, but also are useful for exploiting functional quantum nanophotonic devices.