金属-介质多层膜双曲超材料中高k体等离激元的激发与耦合特性研究

The high-k volume plasmon polaritons (VPPs) in Hyperbolic metamaterials (HMM) made of metal-dielectric multilayers is very difficult to be excited and controlled. Here, we propose constructing metallic nanoantenna array on the surface of HMM. By coupling the LSPs excited in nanoantenna array with the SPPs and VPPs in HMM, the highly efficient excitation of VPPs is expected to be realized. . Furthermore, we will construct a structure composed of a uniform metasurface on HMM. The metasurface consists of metal/dielectric nanostructures. The surface impedance of HMMs can be controlled by the metasurface, so that the radiation of the excited VPPs can be restrained, and the coupling strength between the incident light and the VPPs is enhanced.. The metasurfaces composed by metal/dielectric nanostructure will be prepared in experiment. By controlling the dimensional size and the surface density of the nanostructure, the metasurface-HMM composite structure is capable of angle and polarization-insensitive and near-perfect light absorption in visible wavelength. Lastly, we will investigate the diffraction coupling property of VPPs in HMM resonator array, and micro-nano optics devices with novel transmission characteristic can be realized. This investigation is very important for applications such as spontaneous emission enhancement, sub-wavelength imaging realized by using HMM.

针对金属-介质多层膜双曲超材料中高k体等离激元（volume plasmon polaritons，VPPs) 的激发、调控极其困难，提出在双曲超材料表面构建金属纳米天线阵列，通过金属纳米天线中激发的LSPs与双曲超材料界面SPPs及VPPs耦合作用，期望实现VPPs的高效激发。进一步，构建由金属或者介质微结构散射体组成的非均匀超表面-双曲超材料结构，利用超表面调控双曲超材料表面阻抗，抑制被激发VPPs的辐射泄露，增强入射光与VPPs的耦合强度。并拟在实验上制备基于金属/介质微结构超表面-双曲超材料复合结构，通过对微结构尺寸及表面密度的控制，实现可见光波段可调谐、宽带宽、全方向的超吸收。最后将对由双曲超材料谐振腔构成超表面中VPPs的衍射耦合特性进行研究，基于这些研究构建具有新颖传输特性的微纳光学器件。本研究将对利用双曲超材料实现增强自发辐射，光学超分辨成像等应用具有重要意义。

本项目首先分析了金属-介质多层双曲超材料介电特性及等频率曲线，在理论上证实了金属-介质多层膜的双曲色散特性及其存在区间。随后对双曲超材料中高k体等离激元（BPPs）的模式特征、色散关系、激发特性等进行了研究。并利用耦合波理论在理论上研究了由金属纳米线阵列与金属-介质多层双曲超材料构成复合体系中LSPs与双曲超材料界面SPPs、BPPs等模式的相互耦合特性。随后在理论及实验上对由二维纳米孔阵列、纳米锥阵列构成超表面结构中不同类型等离激元的耦合进行了研究，并通过调控等离激元的耦合实现对结构异常传输特性的调控。在此基础上研究了具有二维纳米孔阵列双曲超材料中BPP模式共振腔模式与SPP模式耦合特性，由于双曲超材料结构中BPP和SPP的耦合使得该结构透射峰的线宽大幅减小。最后，为了进一步提高BPP模式的激发效率，我们基于金属-介质多层膜双曲超材料，构建了新型复合一维光栅结构。在该结构中由于BPPs腔谐振模式与沟槽SPPs腔共振模式之间的耦合，实现了对结构损耗的有效抑制。该工作为等离子体器件设计提供了全新的调控理论，并对宽波段超吸收、利用双曲超材料增强分子自发辐射等方面有着重要的科学意义。