Fig. 1. Hardware entrances and corresponding new display forms of the metaverse

Fig. 2. Related technology development process of AR-3D display

Fig. 3. Research progress of head-mounted stereoscopic AR-3D display technology. (a)(b) Schematic diagram of waveguide coupling principle based on polarization-multiplexed metagrating and experimental effect of stereoscopic AR-3D display^[36]; (c)(d) principle diagram of binocular AR-3D display based on Maxwellian-view and computer-generated holography and experimental effect diagram of telephoto depth display^[40]

Fig. 4. Research progress of head-mounted multi-plane AR-3D display technology. (a)‒(c) Dual-plane AR-3D display principle diagram based on liquid crystal variable retarder and polarization selectivity system and effect display diagram^[47]; (d)(e) schematic of large depth of field, continuous plane, near-eye 3D display based on adjustable optics, and fast spatially adjustable backlight and experimental installation drawing^[48]

Fig. 5. Research progress of glasses-free multi-plane AR-3D display technology. (a)(b) Principle diagram of dual-mode AR-3D head-up display system based on holographic combiner and PDLC film and display effect^[50]; (c)(d) principle diagram, experimental device diagram, and display effect diagram of wavelength selective multi-plane AR-3D display based on dynamic adjustable reflective PB phase lens^[51]

Fig. 6. Research progress of head-mounted light-field AR-3D display technology^[55]. (a) Photograph of assembled meta-II micro-display panel; (b) principle diagram of real-time EIA rendering method; (c) 3D images with motion parallax and focus cues simulated in a meta-II display device; (d) experimental results of real motion parallax and focus cues in meta-II display device

Fig. 7. Research progress of glasses-free light-field AR-3D display. (a) Schematic diagram of optical combinator based on pixelated interleaved multistage diffractive lens^[60];(b) actual effect of glasses-free AR-3D display at different angles and depths^[60];(c) principle diagram of double-sided view AR-3D display based on diffractive waveguide^[62]; (d) experimental results of dual color and double-sided view AR-3D display^[62]

Fig. 8. Application scenes of light-field AR-3D display. (a) Smart education scene; (b) smart cultural tourism scene