Fig. 1. MIM waveguide structure diagram

Fig. 2. Transmission spectra of a single H-type resonant cavity, a single vertical branch, and the whole system

Fig. 3. Magnetic field distribution along the z-axis of Fano resonance peaks and valleys and their height expressions. (a) Magnetic field distribution at peak λ=1080nm; (b) magnetic field distribution at valley λ=1100nm; (c) magnetic field pattern height expression at peak λ=1080nm; (d) magnetic field pattern height expression at valley λ=1100nm

Fig. 4. Performance change of sensor system under different refractive indices. (a) Refractive index with wavelength; (b) sensitivity; (c) quality factor

Fig. 5. Influence of geometric parameters on Fano resonance of the system. (a) Relationship between peak shift of Fano resonance and variation of axial length; (b) linear fitting relationship between axial length and Fano resonance wavelength; (c) relationship between Fano resonance line type and variation of branch width; (d) linear fitting relationship between branch width and Fano resonance wavelength; (e) relationship between transmission spectrum and coupling distance g; (f) relationship between right valley wavelength and coupling distance g; (g) variation of parameters ΔT and Δλ with coupling distance g