Numerical analysis of high-Q multiple Fano resonances

We design and numerically analyze high-quality (Q) multiple Fano resonances based on a hybrid metamaterial waveguide structure, which consists of T-shaped gold cut wires placed on a dielectric board waveguide. There are three sharp Fano peaks arising from the interference between plasmon dipole mode and different guided modes. The physical origin of obvious Fano behaviors is explained by the three-level plasmonic system and slab waveguide theory. The largest Q-factor reaches 547, and modulation depth of the peak C can get to nearly 100%, making it possible to perfectly realize the Fano switch function. Combining the cramped spectral lines with large near-field confinement, we demonstrate an optical refractive index sensor with a sensitivity of 4920 nm/RIU and a figure of merit of 188. This work provides a way to obtain multiple high Q-factor Fano resonances, which can widen channels for fabricating devices in biochemical sensing and optical switching.