High-Saturation Full-Color Printing with All-Dielectric\nChiral Metasurfaces

Abstract

Precise\nengineering of light–matter interactions has enabled\na wide variety of approaches to create brilliant structural colors\nthat overcome the limitation of pigments and dyes in sub-diffraction\nresolution, enhanced durability, and environmental friendliness. Techniques\nunitizing photonic crystals, surface plasmons, Mie resonances, or\nFabry–Perot cavities have been extensively investigated for\napplications ranging from coloration, displays, sensors to security\ndevices. However, creating high-saturation colors in the bright-field\nenvironment remains challenging owing to the critical requirement\nof high-index contrast or homogeneous environment. Here, a generic\nstrategy is reported to generate high-saturation bright-field structural\ncolors in the cross-polarization spectra with all-dielectric chiral\nmetasurfaces consisting of arrays of TiO₂ half-gammadion-shaped\nresonators. We experimentally demonstrate that vivid reflective structural\ncolors can be achieved across the visible spectrum by carefully engineering\nthe chiral resonators. It is shown that the reflectance at off-resonant\nwavelengths and higher-order resonances are strongly suppressed in\nthe cross-polarization reflection spectrum, leading to extremely high-saturation\ncolor printing with a gamut larger than standard RGB (sRGB). Excellent\ncolor performance for sRGB tricolors is further demonstrated. The\nsimple structure, facile fabrication, wide color gamut, and high saturation\nmake the chiral structural colors competitive for polarization optical\napplications in micro-display, nanoprinting, anti-counterfeiting,\ndata storage, and information encryption.