Fig. 1. Schematic of generalized Snell's law of refraction^[37]

Fig. 2. Principle of metasurface optical field modulation. (a) Propagation-phase metasurface device^[45]; (b) geometric phase metasurface^[49]; (c) combination of propagation phase and geometric phase^[54]

Fig. 3. Several common optical structure diagrams of AR near-eye syetem. (a) Structure diagram of Birdbath optical system; (b) structure diagram of freeform prism optical system; (c) structure diagram of freeform mirror optical system; (d) structure diagram of cascaded mirror optical system; (e) structure diagram of grating waveguide optical system; (f) structure diagram of off-axis holographic optical element system

Fig. 4. Design of AR optical system based on metasurface and free-form surfaces. (a) Ray tracing simulation of freeform surface near-eye display based on phase mask^[76]; (b) schematic diagram of AR optical system based on freefrom reflection structure^[76]; (c) schematic diagram of AR optical system based on hypersurface^[76]; (d) schematic diagram of AR optical system based on composite metasurfaces and phase mask^[77]; (e) schematic diagram of composite metasurfaces structure^[77]

Fig. 5. Design of AR near-eye display optical system based on metaform mirror^[78]. (a) Schematic diagram of principle of metaform; (b) schematic diagram of miniature imager design using a metaform mirror; (c) schematic diagram of phase distribution of metaform; (d) image of a successful metaform and a scaled-up view of an SEM image of a set of fabricated nano-tokens

Fig. 6. Schematic diagram of retinal projection display based on Maxwell's observation method

Fig. 7. Design of hyperlens-based retinal projection display ^[80]. (a) Illustration of AR prototype; (b) photograph of fabricated see-through metalens with a diameter of 20 mm and an SEM image of part of device; (c) schematic illustrations of optical behavior of see-through metalens under several incident light conditions;(d) single-color AR images with real objects for red, green, and blue colors

Fig. 8. Design of AR display system based on large-size achromatic superlens^[81]. (a) Schematic diagram of AR mode based on a large-size achromatic metalens; (b) an SEM image of part of metlens; (c) example of experimental image results of AR device

Fig. 9. Design of AR near-eye display system based on metasurface coupling elements. (a) Schematic diagram of a multilayer metaface-based AR waveguide system with metasurface structure as coupling-in element^[82]; (b) schematic diagram of a metasurface-based AR waveguide system^[83], both coupling-in and coupling-out elements are metasurface

Fig. 10. Design of an AR near-eye display system based on hypersurface and LHOE^[88]. (a) Recording and reconstruction process of LDHOE; (b) experimental results, virtual letters floating in real world

Fig. 11. Design of AR near-eye display system based on transmissive super-surface holograms^[89]. (a) Schematic diagram of system structure; (b) optical perspective scene captured by camera when focusing at 2 diopters

Fig. 12. Metasurface-based monochromatic contact lens design^[90]. (a) Schematic diagram of a metasurface-based AR near-eye display; (b) experimental results with human eye looking at real world with auxiliary virtual information