Fig. 1. All-Si metasurface polarizing bandpass filters on 12 inch wafers^[28]. (a) Photography of Si metasurface; (b) macroscopic diagram of metasurface; (c) top-view SEM image of a 3×3 Si array; (d) SEM image of Si structure located at wafer center; (e) cross-sectional TEM image of AA'

Fig. 2. Metasurface for holographic near-eye display^[30]. (a) Unit cell of Huygens' metasurface; (b) image of metasurfaces; (c) virtual subject focused at the distance of 2 m; (d) real and virtual objects focused at distance of 2 m

Fig. 3. Printable Si nanocomposite metalens^[10]. (a) Schematic of the metalens printing process; (b) SEM image of master mold; (c) SEM image of soft mold composed of patterned h-PDMS layer; (d) a buffer layer of PDMS; (e) image of the printed metalens on a lens tube, and the green circle is the metalens

Fig. 4. SEM image of silicon nitride waveguide cross section^[42]

Fig. 5. Varifocal zoom metalens based on silicon nitride^[36]. (a) Process flow for fabricating multiple large area metalenses in parallel using high-throughput stepper lithography-based processing; (b) photography of metalens; SEM images of fabricated nanoposts are shown at (c) normal inciedence and (d) 45° incidence

Fig. 6. TiO₂ metasurfaces prepared by nanoimprinting and Sol-gel method^[48]. (a) Photo and SEM image of Si master; (b) photo and SEM image of TiO₂ soft mold; (c) SEM image of TiO₂ replica and Fourier transform result of master; (d) AFM image of TiO₂ and statistic results of pillar volume and height; (e) optical microscope image of TiO₂ microcolumn and height profiles of three AFM images taken at the points of C, M, and S

Fig. 7. Fabrication of printable TiO₂ metasurfaces^[49]

Fig. 8. TiO₂ metasurface with high aspect^[49]. (a) SEM images of master and samples 1, 10, and 15; (b) SEM images of sample 15

Fig. 9. Nanoimprinted perovskite metasurfaces^[52]. (a) SEM image of nanostripe; (b) SEM image of nanohole

Fig. 10. Perovskite metasurfaces manufactured by soft lithography^[53]. (a) Preparation process; (b) mold filling process

Fig. 11. Precise three-dimensional generation of GQDs inside PDMS^[57]. (a) Schematic of the dot array; (b) two-dimensional fluorescent images obtained at different z-axis focuses, the scale bars indicate 100 μm; (c) three-dimensional reconstruction fluorescent image; (d)(e) side and front views, the scale bars indicate 250 μm