Angle-invariant eye-friendly color filter capitalizing on a multi-layer nano-resonator integrated with highly reflective/absorbing media

Abstract

Color filter with a combination of excellent angle insensitivity and high near-infrared shielding absorption is essential to broaden its practical application of harsh environment. However, there are few attention on the near-infrared absorption of color filter, prominent to the protection of human eyes in some special application scenarios. Herein, we propose and develop a dual-function color filter composed of four-layer silicon/titanium planar nanostructure that integrates with both angle-invariance and near-infrared shielding. The proposed color filter enables the creation of three reflective color primaries of cyan, yellow, and magenta (CYM) employing a combination of Fabry-Perot resonance and anti-resonant effect with the tuning of silicon thickness. The created reflective colors are less sensitive over a wide angle of incidence up to 60°, where the center wavelength of optical spectra is shifted by below 1.8%. Besides the angle-invariant performance, the color filter can effectively shield near-infrared light with a 70% average absorption under normal incidence. Moreover, this filter’s thermal stability at 500°C demonstrates its feasibility for extreme environments. The demonstrated color filter is suitable for architectural decorative coatings and outdoor protective coatings in some harsh environment with strong near-infrared radiation, such as glass smelting, steel forging, and long-term sunlight exposure.