Fig. 1. Schematic diagram of preparation of microsphere shell by emulsion self-assembly method

Fig. 2. Scanning electron microscope images of microsphere shells. (a)-(c) SEM images of microsphere shells with different sizes; (d)-(f) SEM images of defective microsphere shells; (g) large size microsphere shell and (h) its surface local magnification (inset is the golden sphere particle size distribution histogram)

Fig. 3. Optical properties of a microsphere shell with size parameters d=250 nm and L=2. (a) Comparison between the calculated scattering spectra using the sphere packing model and the effective refractive index model, and experimental test results. The inset shows the effective refractive index map of the microsphere shell on the left and the SEM image of the microsphere shell on the right; (b) near-field distributions of the microsphere shell at 685 nm and 844 nm wavelengths; (c) multipole scattering spectra of microsphere shells, with dashed lines representing the phase difference between P_x and M_y, and black circles and arrows indicating the main multipole contributions to Mie scattering; (d) far-field radiation pattern of the microsphere shell at 917 nm wavelength

Fig. 4. Optical characteristics of microsphere shells with d=500 nm and L=9. (a) Comparison chart between the calculated scattering spectrum using the effective refractive index model and the experimental test results. The inset shows the SEM image of the microsphere shell; (b) multipole scattering spectra of microsphere shells, with circles and arrows indicating the main multipole contributions to Mie scattering

Fig. 5. Influence of the number of layers in microsphere shells on their scattering characteristics. (a) Two-dimensional distribution maps of scattering spectra of microsphere shells with different numbers of shell layers; (b) experimental results (solid line) and numerical calculation results (dashed line) of scattering spectra of microsphere shells with different sizes. The circles and arrows in the figure indicate the main multipole contributions to Mie scattering

Fig. 6. SEM images of microsphere shells with different size and number of shells

Fig. 7. Relationship between the diameter and number of shell layers of microsphere shells. (a) Scatter diagram of relationship between diameter of microsphere shell and number of shell layers; (b) dark-field scattering spectra of microsphere shells with different sizes, with SEM images of microsphere shells shown on the right side

Fig. 8. Scattering spectra and refractive index sensitivity curves of microsphere shell structures under different refractive indices. (a)(c) Impact of different refractive indices on the scattering spectra of microsphere shells, with the gray shading indicating the region of observed resonance peaks; (b)(d) refractive index sensitivity curves