All-dielectric high saturation structural colors enhanced by multipolar modulated metasurfaces

Abstract

A visible light depth modulation based on a metasurface consisting of TiO2 nanorings and SiO2 substrate is proposed to significantly enhance the saturation and structural colors’ gamut. Compared with the nanostructure of the TiO2 nanodisks, the developed TiO2 nanorings can enhance monochromatic excitation by inhibiting the multipole mode, particularly electric quadrupole (EQ) mode at a shorter wavelength. Furthermore, when TiO2 nanorings are combined with a refractive index matching layer - water, reflection bandwidth, and background reflection are reduced, and the brightness and color purity are significantly enhanced. The novel and unique nanostructures developed can generate a significant gamut of 140% sRGB and 103% Adobe RGB. Additionally, the color structure based on the TiO2 nanoring metasurface is sensitive to the surrounding medium’s refractive index and can be employed in sensor display and other fields, as well as to amplify color information in high resolution display and imaging applications.