Fig. 2
a Recorded color palette of the reflective subtractive colors as functions of the period P (varying from 150 to 240 nm in an increment of 10 nm) and diameter D (varying from 70 to 140 nm in an increment of 10 nm). Each palette square has a size of 8 × 8 μm2, and the whole array is under illumination by an un-polarized white light. b CIE1931 chromaticity diagram overlaid with the black points corresponding to the colors extracted from a. Experimental (c) and simulated (d) reflective spectra of the nanostructure arrays with different geometrical parameters. For example, “70–240” means D = 70 nm, P = 240 nm. e Contour map of the experimental reflective spectra as a function of the incident wavelength and period. The period P changes from 180 to 240 nm, while keeping D = 100 nm as a constant. f Experimentally reflection contour map for nanostructure arrays with different diameters changing from 70 to 140 nm at a constant period of 230 nm. The white asterisks represent the valleys’ positions (λmin), and the white dashed lines refer to the fitted straight lines with the corresponding valleys