Plasmonic color printing based on third-order gap surface plasmons [Invited]

Metasurfaces for color printing rely on the resonant interaction of light with nanostructures, which translates to small physical resonator sizes for visible wavelengths, thus demanding very high fabrication accuracy that necessitates low-throughput processes and prevents the economical large-scale coloration and printing. Through the use of third-order gap plasmon resonances, element sizes necessary for visible resonances can be scaled to be compatible with several large-scale techniques for nanofabrication while retaining the capability of generating vivid colors. We demonstrate this using a 450-nm-periodic gold nanodisc array on SiO2 of different thicknesses (20, 40 and 50 nm) atop a thick gold substrate - a composite structure supporting gap plasmon resonances for both linear polarizations. A third-order resonance occurs for discs of 300 nm diameter and larger, while first-order resonances occur below 100 nm for red light (630 nm). By fabricating nanodiscs of different diameters, we observe vivid shades of red and green colors, with dark shades for third-order gap plasmon nanodiscs resonators due to inherent losses and bright shades for small discs of fundamental resonance counterparts. The third-order gap plasmon based nanodiscs are further spectrally characterized and tested for uniformity and reproducibility by demonstrating printed patterns. The significant improvement in both size and color range using the approach of higher-order based resonances can have a significant impact on the practical applicability and economic feasibility of plasmonic color printing.