​​All-dielectric Grating Structure Color Filter

Fig. 1 Schematic diagram of the all-media grating structure

Compared with the traditional color dyes, the structural color has the advantages of high resolution and good stability and can achieve color switching in the visible range. Due to the increased loss of the plasma hypersurface, researchers have proposed another all-media hypersurface structure; however, high-order dipole resonance modes in the short-wave range reduce the color saturation. Recently, researchers have proposed a feasible scheme to suppress the higher-order dipole modes.

A research group led by Professor Jinsong Gao at the Changchun Institute of Optical Precision Machinery and Physics, Chinese Academy of Sciences, has proposed a narrow-bandwidth, high-quality-factor, all-dielectric grating-structured color filter in a study published in Optics Express.

Using the time-domain finite-difference method, the researchers conducted a comprehensive comparative study of HfO2 gratings and SiO2/HfO2 gratings. They found that the addition of the SiO2 layer effectively suppressed the tendency of higher-order dipole modes to be generated, thus improving the saturation of the structural color. The researchers explained the physical mechanism of this result through magnetic field distribution and electric field vector plots. They explored the effects of structural parameters on the spectral profile and polarization state sensitivity.

Based on the results of this study, the researchers designed an all-dielectric grating. The grating has a reflectance close to 1 at the peak and a transmittance of more than 99% at the non-resonant peak position; the achievable chromaticity coordinates occupy a large part of the CIE-1931 chromaticity diagram. By adjusting the duty cycle, the researchers achieved excellent spectral characteristics with a half-peak full width of 2 nm and a quality factor of Q = 424.5.

The researchers believe this kind of all-dielectric grating has the excellent characteristics of high structural color quality, low half-peak full width, and high-quality factor, which is of great significance in sensing, display imaging, and so on.

Article in: Yuanhang Zhao et al., Multi-layered all-dielectric grating visible color filter with a narrow band and high-quality factor, Optics Express (2022). DOI: 10.1364/OE.453155.