Tunable Fano resonance in MDM plasmonic waveguide with a T-shaped resonator coupled to ring resonator

Tunable single, double, and triple Fano resonance is achieved based on MDM (metal-dielectric-metal) plasmonic waveguide. An asymmetric T-shaped resonator is utilized to achieve single Fano resonance, and one or two ring resonators coupled to the asymmetric T-shaped resonator is applied to realize double or triple Fano resonance. The dependences of the structural parameters on the Fano transmission properties are studied carefully. As an example, the potential applications in the area of nanoscale refractive index sensors and slow-light devices are also shown in the paper. The proposed structures can also be used in the plasmonic filters, switches and so on.