Independently tunable triple Fano resonances in plasmonic waveguide structure and its applications for sensing

A surface plasmon polaritons (SPPs) waveguide structure composed of a metal–insulator–metal with baffle, special square cavity (SSC), and ring (RC), is proposed to realize independent tuning in triple Fano resonances. Using the finite element method, magnetic field distributions optical transmission spectra are analyzed detail. The simulation results show that achieves resonances originated from two different mechanics. One occurs RC, others occur SSC. By regulating parameters SSC these can be well tuning, independently realized multiple resonances, which provides flexibility for applied devices. In addition, exhibits great performances refractive index sensing biosensing. maximum sensitivity 2350 nm/RIU, there good linear relationship between resonance wavelength index. Due tunability, SPPs may potentially used micronano-optical devices, especially on-chip sensor.