Figure 2

Scattering (a) and absorption (b) spectra of the single core-shell nanosphere calculated per Mie theory. A medium of index 1 was used in background. The inset in (b) is the scattering-to-absorption ratio S, indicating that the core-shell nanostructure has broadband external field enhancement which exceeds parasitic absorption. The diameter of the core is set as 120 nm and the thickness of the coating shell t is 15 nm. (c) The individual scattering spectra of an Au core, a hollow SiO2 shell, a core-shell nanosphere and the sum value of an Au core and a hollow SiO2 shell. The inset schematically illustrates the oscillator model. The golden sphere and the blue shell stand for the Au core and the SiO2 shell, respectively.