Fano resonance in a symmetric waveguide system with different filled insulators

Anti-symmetric waveguide mode is firstly excited in a symmetric plasmonic structure by filling different materials. This waveguide system consists of a rectangle cavity, which is divided into two parts by a silica strip. Simulation results show that by filling different materials in the two parts of the cavity, both of the symmetric and anti-symmetric waveguide modes can be excited in the cavity. The interaction of the different waveguide modes, gives rise to the Fano resonances. Because of different origins, these Fano resonances exhibit different dependence on the parameters of the structure and can be easily tuned. This has important applications in highly sensitive and multiparameter sensing in the complicated environments. The mechanism based on different filled materials paves a new route to exciting anti-symmetric waveguide mode, and the utilization of the anti-symmetric mode in the MIM waveguide provides a new possibility for inducing Fano resonances.