Appl Opt. 2022 Feb 20;61(6):1275-1283. doi: 10.1364/AO.450084.
A base plasmonic metal-insulator-metal (MIM) waveguide structure consisting of a baffle waveguide and an obround-shaped resonator is designed to produce Fano resonance. The simulation results exhibit that double Fano resonances can be achieved. Based on this structure, an inner obround-shaped resonator is spliced to the former obround-shaped resonator through a slot resonator to form the expanded structure. Then quadruple Fano resonances are produced by the interference between the broadband continuous state arising from the baffle waveguide and the narrowband discrete state arising from the interaction among the inner obround-shaped resonator, the outer obround-shaped resonator, and the slot resonator. The Fano resonance and refractive index sensing characteristics are investigated, and the sensitivity and the figure of merit can reach 1636 nm/RIU and 33562, respectively. Furthermore, the structure filled with blood plasma can be used for detecting plasma concentrations with different refractive indices, and the sensitivity can reach 2.88⋅/. The proposed structure with the simple baffle waveguide and obround-shaped resonators may have potential applications in biosensing and nanoscale optical sensing.
设计了一种由挡板波导和椭圆形谐振器组成的基底等离子体金属-绝缘体-金属(MIM)波导结构,以产生 Fano 共振。模拟结果表明,可以实现双 Fano 共振。基于该结构,通过一个槽谐振器将内部椭圆形谐振器拼接到外部椭圆形谐振器上,形成扩展结构。然后,通过挡板波导产生的宽带连续态与内部椭圆形谐振器、外部椭圆形谐振器和槽谐振器之间的相互作用产生的窄带离散态之间的干涉,产生了四重 Fano 共振。研究了 Fano 共振和折射率传感特性,灵敏度和品质因数分别可达 1636nm/RIU 和 33562。此外,填充有等离子体的结构可用于检测具有不同折射率的等离子体浓度,灵敏度可达 2.88nm/RIU。该结构具有简单的挡板波导和椭圆形谐振器,可能在生物传感和纳米光学传感中有潜在的应用。