Full-colour nanoprint-hologram synchronous metasurface with arbitrary hue-saturation-brightness control

Abstract

The colour gamut, a two-dimensional (2D) colour space primarily comprising hue and saturation (HS), lays the most important foundation for the colour display and printing industries. Recently, the metasurface has been considered a promising paradigm for nanoprinting and holographic imaging, demonstrating a subwavelength image resolution, a flat profile, high durability, and multi-functionalities. Much effort has been devoted to broaden the 2D HS plane, also known as the CIE map. However, the brightness (B), as the carrier of chiaroscuro information, has long been neglected in metasurface-based nanoprinting or holograms due to the challenge in realising arbitrary and simultaneous control of full-colour HSB tuning in a passive device. Here, we report a dielectric metasurface made of crystal silicon nanoblocks, which achieves not only tailorable coverage of the primary colours red, green and blue (RGB) but also intensity control of the individual colours. The colour gamut is hence extruded from the 2D CIE to a complete 3D HSB space. Moreover, thanks to the independent control of the RGB intensity and phase, we further show that a single-layer silicon metasurface could simultaneously exhibit arbitrary HSB colour nanoprinting and a full-colour hologram image. Our findings open up possibilities for high-resolution and high-fidelity optical security devices as well as advanced cryptographic approaches.

Broadband metamaterials and metasurfaces: a review from the perspectives of materials and devices

“…In [169], it has been demonstrated that with two-step (on and off) amplitude manipulation it is possible to reduce speckle noise, an intrinsic problem of phase-only holograms. By combining a color filter and a meta-hologram, meta-hologram with microprint functionality is presented [177][178][179]. Particularly, in [177], a color filter and meta-hologram are realized on a single metamaterial.…”

“…By combining a color filter and a meta-hologram, meta-hologram with microprint functionality is presented [177][178][179]. Particularly, in [177], a color filter and meta-hologram are realized on a single metamaterial. While most studies have assumed either the reflection mode or the transmission mode of operation, in [170], a meta-hologram that simultaneously generates different images on the reflection and transmission sides has also been proposed.…”

Multifunctional Geometric Metasurfaces Based on Tri‐Spectral Meta‐Atoms with Completely Independent Phase Modulations at Three Wavelengths

“…In addition, most of the reported multiwavelength metadevices only work at two wavelengths due to the strong coupling effect for closely spaced resonators. Up to now, very few 2-bit tri-wavelength and quad-wavelength metallic metadevices at reflection mode with the linear polarization [31][32][33] and tri-wavelength dielectric metadevices at transmission mode with the circular polarization [34][35][36] have been demonstrated. Compared to the propagation phase modulation (usually for linear polarization), the metasurface based on geometric phase modulation (for circular polarization) is favored, where 2 phase modulation could be continuously achieved by rotating the resonator instead of tuning the geometric size of the resonator.…”

Three‐Channel Metasurfaces for Simultaneous Meta‐Holography and Meta‐Nanoprinting: A Single‐Cell Design Approach

“…However, with this approach the information density of each metasurface is not increased at all. Adjusting the complex transmission coefficients of metasurfaces is another feasible way for merging holography and nanoprinting, which is realized by utilizing the coupling between two nanostructures [ 28 ] or optimizing the dimensions of nanostructures so they can act as wave‐plates with different phase delays. [ 29 ] In these schemes, the amplitude distribution of transmitted light, which is determined by the grayscale of nanoprinting pattern, limits the diffraction efficiency of holographic image.…”