Fig. 1. Structure diagram of DBR coated with metal grating

Fig. 2. Reflection spectrum generated in DBR structure coated with complete metal layer (Magnetic field modulus distribution corresponding to reflectance dip is shown in left inset, and intensity distribution of magnetic field components along vertical line of center of periodic element is shown in right inset)

Fig. 3. Transmission spectrogram of model. (a) Transmission spectra of gratings with different metal film thicknesses; (b) evolution of peak transmittance and center wavelength with varied h_m from 4 to 20 nm

Fig. 4. Magnetic field distribution of model. (a) Distribution of magnetic field component Hy for hm=0 and 8 nm; (b) profile of magnetic component Hy along axis of x=0

Fig. 5. Relationship between characteristic constants of transmission peak and metal film thickness h_m. (a) Evolution of FWHM and Q; (b) evolution of sensitivity S and FOM

Fig. 6. Contour map of model. (a) Variation trend of transmittance with medium index and incident wavelength; (b) distributions of magnetic field component Hy at points A, B, and C depicted in (a)

Fig. 7. Performance indicators of transmission peaks of 3-5 order resonant modes in grating slots under different duty ratios. (a) Sensitivity; (b) FOM value; (c) detection range

Fig. 8. Performance indicators of transmission peaks of 3-5 order resonant modes generated by different grating thicknesses hg. (a) Sensitivity; (b) FOM value; (c) detection range