Polarization-Sensitive Structural Colors with Hue-and-Saturation Tuning Based on All-Dielectric Nanopixels

Structural colors generated by the plasmonic resonance of metallic nanostructures, particularly aluminum, have been intensively studied in recent years. However, the inherent Ohmic loss and interband transitions in metals hinder the high efficiency and narrow bandwidth required for pure colors. Here, arrays of asymmetric titanium oxide elliptical nanopixels on a silica substrate are utilized to realize polarization-sensitive structural colors with high saturation, high efficiency (more than 90%), and high resolution. Owing to Fano resonance resulting from the interference between the radiating waves of dipole resonances and directly reflected waves, perfect narrow reflected spectra can be formed with nearly ideal efficiency in the visible spectrum based on this all-dielectric nanostructure. In particular, hue- and saturation-tuned colors can be simultaneously obtained under two orthogonally polarized incident lights with apparent color contrast. Based on the superior properties of the titanium oxide metasurface, the proposed design strategy is anticipated to form a new paradigm for practical applications, such as high-density optical data storage, nanoscale optical elements, sensing, security, and so on.