Multidimensional structural coloration from hierarchically designed plasmonic structures

Abstract

We propose a photonic strategy for multidimensional structural coloration that responds to varying illumination conditions. Both theoretical and experimental results verified that the combination of a metal/dielectric/metal cavity with a one-dimensional (1D) metal grating can increase the degree of freedom of structural coloration. We fabricated Ag/MgF2/Ag cavities coupled to 1D Ag gratings (pitches of 400, 570, and 800 nm) and obtained their photonic band dispersions (i.e., angle-resolved reflectance spectra) to unravel their mode characteristics. The 1D Ag grating and Ag/MgF2/Ag cavity induced surface plasmon polariton (SPP) and Fabry-Perot cavity modes, respectively. Notably, only a cavity mode emerged in the s-polarization and gradually blueshifted with increasing angle, whereas in the p-polarization, both SPP and cavity modes appeared and shifted oppositely with changes in the angle, leading to intricate color patterns at different wavelengths, angles, and polarizations. To further un-derstand the effect of each mode upon structural coloration, we obtained the distribution of electric field in-tensity using rigorous coupled-wave analysis simulation, which identified multiple photonic bands in the p -polarization as various SPP-mediated hybrid modes.