MIM波导耦合类云朵腔的多Fano共振传感特性研究

Multi-Fano Resonant Sensing Characteristics of MIM Waveguide Coupled with Cloud Like Cavity

为实现光折射率传感器小结构、高灵敏度的要求,根据表面等离极化激元的透射特性,提出了一种单挡板金属-介质-金属(MIM)波导耦合类云朵腔结构。此结构引用“腔中腔”的理念,在近场耦合作用下,类云朵腔所形成的较宽的连续态与金属挡板所形成的较窄的离散态经过干涉相长相消,可以产生三重不同模式的法诺共振。结合耦合模理论,对三重法诺共振的产生机理进行分析,并运用有限元分析法对此结构进行模拟仿真,定量分析了不同结构参数对折射率传感特性以及优质因子的影响。结果表明,三种共振模式的灵敏度分别为600,800,1083 nm/RIU,优质因子分别为5.08×10;、3.56×10;和1.17×10;。

In order to realize the requirements of small structure and high sensitivity of optical refractive index sensor, a single baffle metal-insulator-metal(MIM) waveguide coupled with cloud like cavity is proposed according to the transmission characteristics of surface plasmons. This structure refers to the concept of "cavity within a cavity". Under the action of near-field coupling, the wide continuous state formed by a cloud like cavity and the narrow discrete state formed by a metal baffle can be eliminated by interference, resulting in three Fano resonances with different modes. Combined with the coupling mode theory, the generation mechanism of triple Fano resonance is analyzed, and the finite element analysis is used to simulate the structure, and the influence of different structural parameters on the refractive index sensor characteristics and quality factors is quantitatively analyzed. The results show that the sensitivity of the three resonant modes are 600, 800 and 1083 nm/RIU, and the high quality factors are 5.08×10;, 3.56×10;, and 1.17×10;, respectively.