Fano resonance and its application using a defective disk resonator coupled to an MDM plasmon waveguide with a nano-wall

A coupled plasmonic system for Fano resonance, of which a defective disk resonator is side coupled to an MDM (metal-dielectric-metal) waveguide with a nano-wall, is proposed and investigated numerically and theoretically via FEM (finite element method). Simulation results show that the system can generate double Fano resonances, which result from the interactions between two narrow discrete states induced by the defective disk resonator and one broad continuous state excited by the nano-wall inserted in the MDM waveguide. The peak wavelengths of the two Fano resonances can be easily adjusted by changing the structure parameters, which indicates that the proposed structure has better flexibility in design. Additionally, the properties of the designed structure in the applications of refractive index sensing, temperature sensing, and optical switch are studied in detail, which reveals that the proposed plasmonic system may have potential applications for the integrated optical circuits of nanoscale optical filters, sensors, optical switches, optical modulators, and so on.