A Method of Improving the Structural Color Quality of HfO2 Grating Based on Thin Film Filter

Abstract

In order to eliminate the influence of the high-order magnetic dipole modes in the short-wave range of the high-refractive-index dielectric grating, we propose a thin film filter to cut off the “useless” short-wave. In this way, the high-order magnetic dipole can be suppressed, and the quality of the structure color is highly improved after the thin film filter cut off the incident light in the non-resonant band. The combined application of the thin film filter and the grating filter not only avoids the problem of too big film layer thickness, but also reduces the manufacturing process cost. For example, the film system (basic film system 0.5 L H 0.5 L) and thickness of green, 15° and 45° incident film filters are 21 layers, 1.76 μm and 41 layers, 4.02 μm. The color coordinates corresponding to the calculation results occupy a large area on the Commission Internationale de l’Eclairage 1931 (CIE 1931) chromaticity diagram, which proves that this design scheme can effectively improve the structural color quality. This method obtains excellent theoretical simulation results. This has important implications for high-end imaging equipment and sensors.