Study of Fano resonance and its application in MIM waveguide using a k-shaped resonator

In this paper, a plasmonic MIM waveguide consisting of a k-shaped resonant cavity is designed, which can support three Fano resonances. The physical mechanisms behind the multiple Fano resonances are studied with the help of field distributions and the changes of geometric parameters. Further, by varying the refractive index of the dielectric medium filled in the air part of the waveguide, property of refractive index sensing is studied. The maximum sensitivity is up to 1250 nm/RIU and the maximum figure of merit is more than 4000. Eventually the slow-light effect is also investigated, and the results show that the maximum optical delay and the group index are about 0.05 ps and 9.23, respectively. All the results may provide some fundamental references for the design of plasmonic optical waveguide devices, and it will also have potential applications in areas such as nanoscale refractive index sensing, slow-light effects, photonic device integration, and so on.