Stacking of colors in exfoliable plasmonic superlattices.

Color printing with plasmonic resonators can overcome limitations in pigment-based printing approaches. While layering in pigment-based prints results in familiar color mixing effects, the color effects of stacking plasmonic resonator structures have not been investigated. Here, we demonstrate an experimental strategy to fabricate a 3-tiered complex superlattice of nanostructures with multiple sets of building blocks. Laser interference lithography was used to fabricate the nanostructures and a thin-layer of aluminum was deposited to introduce plasmonic colors. Interestingly, the structures exhibited drastic color changes when the layers of structures were sequentially exfoliated. Our theoretical analysis shows that the colors of the superlattice nanostructure were predominantly determined by the plasmonic properties of the two topmost layers. These results suggest the feasibility of the sub-wavelength vertical stacking of multiple plasmonic colors for applications in sensitive tamper-evident seals, dense 3D barcoding, and substrates for plasmonic color laser printing.