Side-Coupled Cavity-Induced Fano Resonance and Its Application in Nanosensor

A compact structure based on plasmonic metal-insulator-metal (MIM) side-coupled cavities for nanosensor is proposed and numerically simulated. Simulation results show that a typical Lorentzian and Fano-like response emerge in the transmission spectrum, and they can be easily tuned by changing the length of the side cavity and the material imbedded in the resonator. Based on above analysis, our structures offer flexibility to design nanosensor with a sensitivity of ~1820 nm/RIU and a figure of merit about 4.5 × 104. By adding another side-coupled cavity, multiple Fano resonances are achieved and the sensing properties are also investigated. Our structures may have important potential applications in highly integrated optical circuits and networks, especially for nanosensor, spectral splitter, and nonlinear devices.