金属壳层手性超材料的表面等离激元光场的实验研究

The research on metamaterials is a frontier topic of nano-photonics, and chirality is an important feature of metamaterials. With the advantage of fabrication in a large area, chiral metamaterials of metal layers can realize circular dichroism (CD) in the visible frequency range. In this project, we analyze the dependence of CD on the geometry parameters of the stacked metal layers and design metamaterials with strong chirality. Furthermore, we study the response of the stacked metal layers to the linearly polarized light, which is helpful in understanding the interaction between light with different polarization and chiral structures. Lastly, utilizing the SPPs scattered imaging system, the SPP filed generated by stacked metal layers will be measured and analyzed to reveal the underlying physical origin of chiral metamaterials. This project may have potential applications in manipulation of SPP, the design of novel chiral metamaterial devices, biological molecule spectroscopy and sensing.

超材料研究是微纳光子学的前沿课题，而手性是超材料的重要特性。其中，金属壳层手性超材料能在可见光波段实现较强圆二色性，而且具有易于大面积制备的优势。本项目拟从分析金属壳层单元结构几何参数对圆二色性谱的影响出发，设计具备强圆二色性的金属壳层超材料。进一步，通过分析金属层超材料对线偏振光的响应，加深对于光波偏振与手性结构相互作用的理解。最后，利用表面等离激元（SPP）散射成像系统测量金属壳层超材料产生的SPP光场，并分析其对圆二色性光谱的影响，揭示金属壳层手性超材料的内在物理机制。本项目在SPP操控、新型手性器件设计和生物分子探测与传感等方面具有潜在应用前景。

基于金属纳米结构的超材料设计是实现表面等离激元（SPP）光场操控的一种重要手段。本项目研究了金属亚波长结构（单狭缝、双狭缝）与不同线偏振光及圆偏振光相互作用激发SPP光场的规律，并基于此实现了多种纳米尺度的干涉光场图样及偏振无关的光聚焦。我们设计了方形金属狭缝结构并进行了实验测量，获得了条纹状、方形晶格阵列和菱形晶格阵列等多种干涉光场图样，并分析了图样随缝宽及入射偏振态的演化特点；将金属亚波长狭缝与菲涅尔波带片（FZP）相结合，设计了偏振无关的FZP超表面透镜，实现了对任意偏振态入射光的聚焦，分析了其频谱响应特性，设计了多焦点的超表面透镜。上述研究成果在集成纳米光子器件设计和粒子操控等方面具有潜在的应用前景。