表面等离激元超晶格超表面调控光学Fano共振及其在Raman检测中的应用

光学Fano共振在生化传感、纳米激光器、光学信息处理等领域具有巨大应用潜力。但Fano共振的同相位超辐射模式与反相位亚辐射模式一般很难独立调控，导致Fano共振线型和光谱位置的调控受到极大限制。本项目拟通过构筑一类表面等离激元超晶格超表面结构，研究超晶格结构中的表面等离激元、宽带超辐射模式与窄带亚辐射模式的激发。围绕近场反相耦合/远场同相耦合与亚辐射模式/超辐射模式之间的关联这一关键科学问题，分析单元结构内的偶极子耦合间距（局部周期）与窄带亚辐射模式的光谱位置之间，以及超晶格结构中单元与单元之间的耦合间距（长程周期）与宽带超辐射模式光谱位置之间的依赖关系，获得利用超晶格结构独立调控两种模式的光谱位置的方法，掌握调控由二者干涉形成的非对称Fano共振线型和光谱位置的规律。以此为基础，探索Fano共振谱的可调性与各种Raman分子的特征谱的匹配关系，研究其在Raman检测中的应用。

Optical Fano resonances show great application potentials in bio-chemical sensing, nanolasers, and optical information processing and so on. However, both in-phase superradiant mode and out-of-phase subradiant mode of Fano resonances are generally hard to control independently, leading to serious limit to manipulate the lineshapes and spectral positions of Fano resonances. This project plans to study the excitations of plasmons, broadband superradiant modes, and narrowband subradiant modes in a kind of surface plasmonic superlattice metasurfaces. To solve the key scientific problem: essential relations between in-phase near-field coupling and subradiant modes as well as ou-of phase far-field coupling and superradiant modes, we will analysis the dependence of spectral positions of subradiant modes on the coupling distance ( local period) between diploes in the unit cells, and that of superradiant modes on the coupling distance (global period) between the unit cells of the superlattices, so as to get the method to independently control the spectral positions of two modes by using geometric parameters of the superlattices, and understand the rule of manipulating the asymmetric lineshapes and spectral positions of Fano resonances formed by interference of the two modes. In terms of the above, we will search for the applications of Fano resonances in Raman detection by using the tunability of Fano resonances to match the feature spectrums of various Raman molecules.