Fig. 1. Schematic of VR/AR display technology. (a) Sketch of VR display system; (b) sketch of AR display system

Fig. 2. VR near-eye display optical elements and imaging techniques. (a) Aspherical lens; (b) Fresnel lens; (c) Pancake with folded optical path; (d) multi-stack folded back freeform surface; (e) heterogeneous lens array; (f) liquid crystal holographic optical element (LCHOE); (g) metasurface, metalens

Fig. 3. AR near-eye display optical elements and imaging techniques. (a) Birdbath optics; (b) off-axis aspherical half mirror; (c) freeform prism; (d) geometric optical waveguide; (e) diffractive optical waveguide; (f) metasurface, metalens

Fig. 4. Micro-display devices. (a) DMD; (b) LCoS^[60]; (c) OLED structure schematic^[61-62]; (d) micro-LED structure schematic^{[61, 63]}; (e) LBS^[64]

Fig. 5. Research progress of metasurface and metalens. (a) V-shaped nanoantenna-based phase-modulated device and fabrication results^[19]; (b) V-shaped nanohole-based metasurface holography^[32]; (c) dielectric metalens and fabrication results^[25]; (d) vortex light generator based on dielectric metasurface^[65]; (e) achromatic metalens based on geometric phase dispersion compensation^[66]; (f) polarization-insensitive achromatic metalens^[67]

Fig. 6. Full-color AR near-eye display of the geometric phase metalens^[78]. (a) Structural unit of the metalens; (b) optical image and SEM image of the fabricated metalens; (c) perspective near-eye display of the metalens; (d) red, green, and blue AR imaging

Fig. 7. RGB achromatic metalens for VR/AR near-eye display^[79]. (a) SEM image of the fabricated metalens; (b) focal intensity distribution of the metalens in the XZ plane; (c) schematic of VR mode; (d) VR image with 7 colors made by RGB mixing; (e) schematic of AR mode; (f) RGB color imaging result of AR

Fig. 8. Inverse design of discrete wavelength achromatic metalens with large aperture for VR near-eye display^[80]. (a) Forward simulator using fast approximate solver; (b) inverse design based on concomitant optimization; (c) schematic of VR near-eye display device consisting of RGB achromatic metalens and micro-LCD; (d) photograph of the fabricated metalens; (e) simulation result of full-color VR imaging obtained by mixing RGB image channels

Fig. 9. Metaform for AR near-eye display^[81]. (a) Schematic of metaform; (b) photograph and locally zoomed SEM image of the fabricated metaform; (c) top-down sketch of AR glasses architecture based on metaform

Fig. 10. Metasurface grating for AR near-eye display. (a) Stereo display based on polarization multiplexed metasurface grating waveguides^[82]; (b) high-performance AR waveguide glasses based on metasurface gratings^[83]

Fig. 11. Metasurface holographic AR display. (a) On-chip metasurfaces for multiplexed AR holographic display^[84]; (b) metasurface-based holographic contact lens for AR display^[87]

Fig. 12. Metasurface-driven OLED display^[88]. (a) Design schematic of a meta-OLED with a metasurface mirror; (b) spectra of RGB electroluminescence of a meta-OLED, with the solid line being the OLED with a metasurface mirror; (c) SEM image of a 1.2 mm subpixel mode meta-OLED and its electroluminescence image; (d) meta-OLED electroluminescence image with pixel size variation

Fig. 13. Metasurface-based LED source. (a) Schematic of the device based on InGaN/GaN quantum well metasurface nanopillars^[89]; (b) metasurface integrated on top of the LED^[90]; (c) schematic of disordered metasurface for enhanced LED light extraction^[91]; (d) schematic of GaN-based LED with disordered metasurface deposited on top^[91]; (e) electroluminescence spectral intensity^[91]

Fig. 14. Process for fabricating dielectric metaurface using electron beam lithography. (a) Flowchart of conformal filling process; (b) flowchart of hard mask etching process

Fig. 15. Large-area metasurface fabricated by DUV lithography^[95]

Fig. 16. Batch fabrication nanoimprinting process for metasurface