Structural Colors Based on Diamond Metasurface for Information Encryption

Structural colors based on dielectric metasurfaces are attractive because of their potential application in next‐generation color printing. However, the commonly used dielectric materials suffer from issues of high light absorption (e.g., Si at blue wavelength) and low resistance to corrosion (e.g., titanium oxide), which greatly limit their application as structural color for information encryption. Here, dielectric‐metasurface‐based structural color constructed on nanocrystalline diamond (NCD) film by using bias enhanced nucleation (BEN) technique is demonstrated. Owing to the formation of highly crystalline diamond by the BEN process, the synthesized NCD film with a thickness of ~500 nm exhibits excellent optical quality with a relatively high refractive index that produces a strong magnetic dipole mode by Mie resonance. To realize the dynamic functionalities of diamond‐metasurface color with high resolution, a periodic array of asymmetric diamond cuboids with high aspect ratio (≈3.1) is fabricated, which produces polarization‐dependent response due to the enhanced Mie resonance. By optimizing the configuration of the diamond‐metasurface system, the color performance is improved with high brightness and a relatively wide gamut. This work demonstrates for the first time that NCD can serve as a robust and highly tunable dielectric platform for application in information encryption. Structural colors based on diamond metasurface are demonstrated by fabricating a periodic array of asymmetric diamond cuboids with high aspect ratio (≈3.1). By optimizing the configuration of diamond‐metasurface system, the color performance is greatly improved with high brightness and a relatively wide gamut (65% of the sRGB).