Fig. 1. Fundamental phase of metasurface. (a) Schematic diagram of generalized refraction law; (b) schematic of generalized reflection law; (c) plasmonic metasurface based on resonance phase^[1]; (d) metasurface based on geometric phase^[2]; (e) metasurface based on propagation phase^[15]

Fig. 2. Simulation results of polarization-multiplexing metasurfaces obtained by finite difference time domain method. (a) Nanopillars for simulation; (b) phase library of nanopillars [graphs in the first row are the transmission coefficients of nanorods for different length L and width W along x- and y-directions (T_x,T_y), and graphs in the second row are the phase shift of birefringent nanostructures in directions of major and minor axes under incidence of online polarized light (ϕ+,ϕ-)]; diagrams of linear-polarization-multiplexing metasurfaces and normalized electric field intensity profiles obtained by simulation when (c) θ=0 and (d) θ≠0, where the upper right illustrations are the Stokes parameters S₁, and the lower right ones are phase distributions; (e) diagram of circular-polarization-multiplexing metasurface and simulation results including normalized electric field intensity profiles, Stokes parameters S₃,_{and phase distributions}

Fig. 3. Related studies of polarization-multiplexing-metasurfaces. (a) Independent control of focus, hologram, and vector beams by orthogonally linear polarization^[15]; (b) linear-polarization-multiplexing bifocal metalens^[6]; (c) polarization-dependent broadband achromatic focusing optical vortex generator (BAFOV) ^[31]; (d) independent control of two holograms by orthogonally circular polarization^[13]; (e) schematic of metasurface enabling arbitrary spin-to-orbital angular momentum conversion^[18]; (f) Airy beams with different acceleration directions generated by metasurface^[19]; (g) spin-dependent Bessel beams generated by metasurface^[27]; (h) generation of perfect optical vortices with different polarization and topological charge under orthogonally circular polarization incidence^[30]; (i) multichannel manipulation of photonic spin Hall effect^[25]; (j) polarization-dependent optical tweezer based on metasurface^[29]; (k) integrated metalforming optical tweezers-optical wrench based on metasurface^[28]; (l) schematic of detection of optical spin and angular momentum^[40]; (m) spiral phase contrast imaging with spin-multiplexing^[21]; (n) schematic of multichannel polarization-multiplexing hologram^[41]; (o) vortex and polarization dependent encryption by using metasurface^[42]; (p) three-channel vectorial full-color hologram based on matesurface^[20]

Fig. 4. Research on wavelength-multiplexing-metasurfaces. (a) Schematic of achromatic metalens in near-infrared bands^[7]; (b) results of color imaging using broadband achromatic metalens in visible band^[8]; (c) schematic of three centrosymmetric dielectric nanopillars and (d) structured light generator based on tri-functional metalens^[53]; (e) supercell of metalens^[54]; (f) schematic of super chromatic dispersive metalens and simulated result of supercell^[54]; (g) schematic of unit cell of metasurface and multicolor hologram^[38]

Fig. 5. Research on metasurfaces based on detour phase. (a) Schematic of unit cell of metasuface consisting of two nanopillars; (b) schematic of designed vectorial hologram and SEM image of metasurface^[59]; (c) optical image and SEM image of logo^[60]; (d) generation of perfect vector vortex beams with linear polarization by matasurface^[61]; (e) schematic of independent complex-amplitude control under orthogonally polarized light incidence^[63]

Fig. 6. Research on metasurfaces based on topological phase and nonlocal metasurfaces. (a) Metasurface based on ET phase and PB phase^[64] (graphs in first row are metasurfaces based on ET and PB phase respectively, graphs in second row are structure and holograms based on ET phase only, and graphs in third row are structure and holograms based on ET phase and PB phase); (b) schematic of nonlocal metasurface^[67]; (c) schematic of metasurface based on chiral BIC and perturbed magnetic field profiles^[68]; (d) schematic of unit cell of nonlocal metasurface and modulation of output light under different environment^[69]