Fig. 1. CS model diagram. (a) Three-dimensional view; (b) top view

Fig. 2. Transmission spectra of CS model

Fig. 3. Transmission spectra of three models. (a) r=5 nm; (b) r=10 nm ; (c) r=15 nm ; (d) r=20 nm

Fig. 4. Transmission spectra of CS model of Au and Ag

Fig. 5. Transmission spectra of CS model with different parameter values r

Fig. 6. Full width at half maxima of peak valley with different parameter values r

Fig. 7. Absorption spectra of CS model with different parameter values r（inset is amplification in the wavelength range of 580 nm to 640 nm）

Fig. 8. Reflectance spectra of CS model with different parameter values r

Fig. 9. Distributions of electric field along the contact surface (xy plane, z= 0)

Fig. 10. Distributions of electric field on xz plane (y= 0)

Fig. 11. Transmission spectra of CS model with different parameter values a. (a) a=20 nm； (b) a=30 nm； (c) a=40 nm； (d) a=50 nm； (e) a=70 nm； （f）a=100 nm

Fig. 12. Electric field distributions of two resonant modes with different parameter values a on the dielectric surface

Fig. 13. Transmission spectra of CS model with different parameter values d. (a) d=10 nm; (b) d=20 nm; (c) d=30 nm; (d) d= 40 nm

Fig. 14. Variation trend of the wavelength of CS model with different parameter values d at the peak and valley

Fig. 15. Transmission spectra of CS model with different parameters values wHC. (a) wHC=5 nm; (b) wHC=20 nm; (c) wHC=30 nm; (d) wHC= 40 nm

Fig. 16. Transmission spectrum analysis charts of different parameter valueswHC. (a) Transmittance trend at peak valley; (b) variation trend of wavelength at peak valley

Fig. 17. Transmission spectra of CS model with different polarization angles β