Fig. 1. Schematic diagram of the nanoring- heptamer metal-dielectric composite structure. (a) Innermost layer with silicon cylinder structure; (b) intermediate layer with silver cylinder structure; (c) single silicon cylinder and six-silver cylinders combination; (d) outermost layer with silicon dielectric ring structure; (e) 2D model and (f) 3D model of the composite structure

Fig. 2. SCS curves of single silicon cylinder, six-silver cylinders, silicon-silver cylinder and composite nanostructures

Fig. 3. Electric field (a)−(c) and charge distribution (d)−(f) at the formant of the spectral line

Fig. 4. Schematic diagram of the influence of structural parameters on scattering spectral line. (a) Influence of different height on scattering intensity and position; (b) contribution of different incidence angles to the scattering cross section; (c) influence of different gaps between seven cylinders on scattering intensity and position; (d) contribution of different cylindrical and annular gaps to the scattering cross-section

Fig. 5. Normalized electric field values at the selected points A, B, C and D, and the black dots in the top right figure are the positions of the four points

Fig. 6. Purcell factor of the ED emitter at four points A, B, C and D, and the black dots in the top right figure are the positions of the four points

Fig. 7. Influence of different air materials on scattering cross section