Transmission and refractive index sensing based on Fano resonance in MIM waveguide-coupled trapezoid cavity

A metal–insulator–metal (MIM) waveguide-coupled trapezoid cavity is presented, and the transmission properties are investigated by finite-element method. Results show that an asymmetric Fano profile emerged in the transmission spectrum, which was caused by the asymmetrical break of the MIM waveguide-coupled trapezoid cavity system. A refractive index sensitivity, Q-factor and FOM of approximately 750nm/RIU, 68.3 and 65.2 were measured based on the Fano resonance. The effect of the structural parameters on the transmission properties is also investigated. The results provide a new possibility for designing high-performance plasmonic devices.