Tailoring the Multiple Fano Resonances in Nanobelt Plasmonic Cluster

Abstract

We theoretically explore the appearances and characteristics of Fano resonances in novel-designed nanobelt cluster, which shows strong modulation depths, and the Fano dips can be tailored independently. The underlying physical mechanisms contributing to Fano resonances are discussed with the electric field enhancement and charge distributions. The results demonstrate that dark-mode excitation is not a necessary condition for the existence of Fano resonances in the nanobelt cluster. The lineshape of the scattering spectra can be regulated effectively by adjusting the geometrical parameters. The effect of the incident illumination polarization orientation is also numerically investigated, indicating that Fano resonances can be completely switched off when the nanobelt cluster is induced by 90°. Moreover, multiple Fano resonances would occur as the number of the nanobelt is increased, which is explained by a physical mechanism based on temporal coupled-mode theory.