Independently Formed Multiple Fano Resonances for Ultra-High Sensitivity Plasmonic Nanosensor

We proposed a plasmonic nanosensor with an ultra-high sensitivity based on groove and ring resonator. Simulation results show that these sharp Fano profiles originate from the interference between the groove and ring resonator. The profile can be easily tuned by changing the parameters of the structure. Moreover, we introduce a new way to achieve multiple Fano resonances through independent processes by adding a side-coupled stub cavity, and the Fano resonances can be tuned independently. These characteristics offer flexibility in the design of the devices. This nanosensor yields an ultra-high sensitivity of ～2000 nm/RIU, which is rarely seen in the previous report. Our structures may have potential applications for nanosensors, slow light, and nonlinear devices in highly integrated circuits.