Fig. 1. Applications of meta-holography^[34-41]

Fig. 2. Advantages of using metasurface as holographic device. (a) Metasurface has larger regulated field-of -view due to diffraction effect; (b) comparison of regulated field-of-view between conventional holographic device and metasurface ; (c) relationship between pixel size of device and diffraction angle

Fig. 3. Smooth dynamic meta-holography display based on spatial multiplexing. (a) Realizing dynamic holographic video display in form of movie projection^[58]; (b) RGB color dynamic holographic video display based on film projection form^[59]; (c) realizing dynamic display with frame rate of 2²⁸ in form of movie projection or in combination with structured light^[35]; (d) interactive metasurface holographic display system^[60]

Fig. 4. Smooth dynamic metasurface holographic display with naked eye based on OAM multiplexing. (a) Design diagram of OAM multiplex metasurface holographic device with discrete spatial frequency distribution^[63]; (b) ultra-high dimensional OAM multiplexed metasurface dynamic holographic display with complex amplitude modulation^[64]

Fig. 5. Meta-holographic display combined with AR. (a) RGB tri-color AR holographic images based on on-chip metasurfaces free from zero-order diffraction^[34]; (b) near-eye display system constructed with metasurface holographic images as display source^[69]; (c) on-chip metasurface integrated system FIOM for AR holographic display^[70]

Fig. 6. Optical field parameter multiplexing for meta-holographic encryption. (a) Single optical field parameter multiplexing by introducing noise into Jones matrix to generate 11 polarization channels^[86]; (b) OAM and polarization multiplexing^[92]; (c) angle-polarization multiplexing^[93]; (d) polarization, wavelength, code combination loading key for meta-holographic encryption^[94]; (e) wavelength and polarization state manipulation in mid-infrared band^[95]

Fig. 7. Diffracted light field multiplexed meta-holography for encryption. (a) Storing phase-modulated information on structured optical fields and metasurface separately^[36]; (b) storing modulation information on two metasurfaces separately^[97]; (c) introducing rotation alignment angles between cascaded metasurfaces to achieve encryption^[98]

Fig. 8. Dynamic meta-holographic for encryption. (a) Using phase change material to realize conversion between crystalline and amorphous states by heating^[37]; (b) stored information varies depending on medium environment^[101]; (c) humidity affects structure of nanocavity units, and dynamic encryption is realized by multiplexing coding^[111]; (d) encoding numbers using chemical reactions combined with polarization states to achieve encryption^[106]

Fig. 9. Meta-holography is combined with other techniques to achieve encryption. (a) Combination of single pixel imaging techniques^[112]; (b) metasurface holographic encryption with real-time key editing^[113]; (c) holographic encryption based on combination of single pixel imaging technology and spatial multiplexing metasurface^[114]

Fig. 10. Holographic metalens imaging with discrete sampling and sub-aperture. (a) Design of transverse dispersive multifocal metalenses^[115]; (b) principle of randomly interleaved holographic broadband diffraction metalens^[38];(c) imaging performance of randomly interleaved holographic achromatic metalens^[38]

Fig. 11. Holographic metalens design that shares full aperture. (a) Principles of holographic interference and reconstructed wavefront of multifocal plasma metalens^[116]; (b) schematic of spin-decoupled metalens with intensity-tunable multiple focal points^[117]; (c) multispectral and polarization imaging is performed using transversally dispersive metalens with ordinary white light beams^[39]; (d) polarization ellipticity calculation result^[39]; (e) reconstructed spectral histogram^[39]; (f) achromatic super-resolution holographic metalens, where focal spot size (FWHM) is smaller than Abbe diffraction limit^[119]

Fig. 12. Meta-holography for other applications. (a) Metasurface spectrometer based on multi-foci metalens^[40]; (b) metasurface demultiplexer formed by TiO₂ nanopillar array^[121]; (c) metasurface-based OAM multi-dimensional demultiplexer^[41]; (d) proof-of-concept experimental demonstration of polarization ellipticity for data information transfer^[41]