Fig. 2

Near-field spectra for various Au-nanodiscs with the same height of 10 nm but different diameters and obtained at the spatial point located on the nanodisc axis and 2 nm above the nanodisc. a Electric field amplitude versus incident wavelengths; b Electric field phase versus incident wavelengths; c Values of all incident wavelengths correlated with the SPR modes identified from (a) and (b). When plotting the curves in (b), vertical shift was applied for better visibility, and the zero-phase lines for each of the curves are plotted as the horizontal dashed lines