表面等离子体耦合共振发射的近场调控及其新型光学成像技术研究

In order to solving the problems associated with the current scanning near-field optical microscopy (SNOM), like the difficulties on extracting the signals from the background noises, the low collection efficiency of the signal and the polarization selectivity of the near-field probes, we propose and study a new type of scanning near-field imaging system based on the nanoparticle-on-film configuration. By making use of the plasmonic coupling between the nanoparticle and the adjacent metal film and the coupled emission of scattering light through the metal film, we focus on improving the performance of the current SNOM system through simplifying the system, speeding up the imaging process, increasing the imaging capacity and improving the imaging resolution. This project includes: 1) studying the plasmonic coupling properties of the NP-on-film configuration under different incident polarization; 2) studying the surface plasmon coupled emission (SPCE) of scattering light induced by the nanoparticle through the metal film, particularly, the effect of SPCE on modulating the resonant spectrum of the configuration and on enhancing the collection efficiency of the signal; 3) building a NP-on-film structure directed SNOM system, realizing the polarization-selectable optical imaging of the focused beam and the super-resolved imaging of the nano-materials and nano-structures. The study on this project is of great value not only on the development of near-field imaging technology, but also on the fundamental research within the area of nano-science.

针对目前近场光学显微镜在信号提取、信号增强、信号偏振选择性等方面存在的缺陷与不足，我们提出一种新型的基于金属颗粒-金属膜（NP-on-film）构型的扫描近场光学成像系统。利用NP-on-film结构的表面等离子体耦合共振和耦合发射效应，我们从简化成像系统、提升成像速度、增加成像信息量、提高成像分辨率等多个方面对目前的近场光学显微镜进行改良。本项目的研究内容包括：1）研究不同入射光偏振下，NP-on-film构型的表面等离子体耦合共振特性；2）研究表面等离子体耦合发射对散射光信号的光谱调制与增强作用；3）搭建基于金属颗粒-金属膜构型的扫描近场光学成像系统，实现对聚焦光场的偏振可选择性成像以及对纳米材料、纳米结构等的超分辨成像。此项研究不仅对近场光学成像技术本身有重要价值，而且作为一种有效的近场表征工具在纳米科学等基础研究领域具有重大意义。

本项目主要研究一种新型的基于金属颗粒-金属膜（NP-on-film）构型的扫描近场光学成像系统，以解决目前近场光学显微镜在信号提取、信号增强、信号偏振选择性等方面存在的缺陷与不足。经过三年的研究工作，项目已顺利完成并达到预定目标，具体完成情况及取得成果包括：a),理论上，利用FDTD建立了金属颗粒/金属膜近场相互作用模型，揭示了NP-on-film结构与不同入射偏振光作用下的耦合共振机理；b),实验上，建立了基于NP-on-film结构的近场扫描光学成像系统，先后实现了对聚焦矢量光场纵向场分量、横向场分量、以及由横向场分量衍生出的自旋角动量的高精度表征。依托本项目共发表了SCI期刊论文10篇，其中中科院1区论文1篇，2区以上论文5篇，此外还有5篇论文已完成尚未发表。共申请国家发明专利3项，其中1项已获授权。培养了研究生2名，博士后2名。本项目所研究的新型近场扫描光学成像技术作为一种有效的近场表征工具在纳米科学等基础研究领域具有重大意义。