Fig. 1. (a) and (b) Schematic illustration of the interrelation between holographic images crosstalk and different incident wavelengths, based on the traditional design strategy for color holographic images of multifunctional metasurfaces. (c) Schematic diagram of a 3D full-color display free of crosstalk. This novel single-cell metasurface is composed of a series of TiO2 nanorods on a quartz substrate.

Fig. 2. (a) Metasurface partial configuration diagram. (b) 3D view and top view of the rectangular meta-atoms. (c) Calculated conversion efficiency (CE) of the chosen meta-atoms in the wavelength range from 450 to 650 nm. (d) Simulated distribution of the normalized electric field component in the y-z cross section when X-polarized light with different wavelengths is incident on the nanorod rotating at θ=45°. (e) Phase of the nanorod changes with the orientation angle at 488, 532, and 633 nm. (f) The CE of the nanorod varies with its length and width at wavelengths of 488, 532, and 633 nm.

Fig. 3. (a) Detailed flow chart of the 3D full color holographic metasurface design. (b) Optimization process of the GS algorithm, where k represents different wavelength channels and N denotes different imaging distances.

Fig. 4. Comparison of the flow charts for (a) traditional metasurface 3D color reconstructed images and (b) single-cell metasurface 3D color reconstructed images. The horizontal axis represents the distance between the metasurface and the reconstructed image accurately.

Fig. 5. (a) Schematic diagram of decoding a single-cell metasurface for 3D color holographic display. (b-I) Metasurface configuration diagram, where the overall size is 450  μm×450  μm and consists of 1000×1000 nanorods. (b-II) Amplitude and phase distributions of three distinct groups of photon bases. From top to bottom, it represents the amplitude distribution of RLL, the phase distribution of GLR, and the phase distribution of BRL. (c) Simulation results of reconstructed holograms at 488, 532, and 633 nm show that the images of ships, aircraft, and cars were successfully reconstructed with color.

Fig. 6. (a) Multidepth display diagram. (b) Depth resolution evaluation flow chart for different imaging planes. (c) RMSE of reconstructed holographic images at different wavelengths in the target areas. (d) Average RMSE of reconstructed holograms in the target region at all target wavelengths.

Fig. 7. Refractive index (n) and extinction coefficient (k) of the TiO2 in the single-cell metasurface [43].

Fig. 8. (a) Simulated transmission spectra of the copolarized and cross-polarized components under left-circularly polarized light incidence. (b) Simulated polarization conversion rate (PCR) under normal incidence.

Fig. 9. Diffraction efficiency of the phase hologram and the amplitude hologram in the single-cell metasurface.

Fig. 10. Manufacturing tolerance of the single-cell metasurface. The simulation conversion efficiency varies with variations in the (a) length, (b) width, and (c) thickness of the TiO2 nanorods.

Fig. 11. Potential fabrication process for the single-cell metasurface.

Fig. 12. Design process of the PSO algorithm for optimizing the size of the nanorods.

Fig. 13. Schematic of the potential experimental setup for color imaging. P, polarizer; M, mirror; QWP, quarter-wave plate; OL, objective lens; HWP, half-wave plate; DM, dichroic mirror.

Fig. 14. (a) Flow chart of the multiplane amplitude GS algorithm. (b) Flow chart of the multiplane phase GS algorithm. FFRT, forward Fresnel transform; IFRT, inverse Fresnel transform.

Fig. 15. (a) Schematic diagram of decoding a single-cell metasurface for 3D color holographic display. (b) Metasurface whole/partial configuration diagram. (c) and (d) Far-field holographic image reconstruction based on scalar diffraction simulation and vector diffraction simulation.