Fig. 1. Principle of multiple OAM-beam detection through single metasurface. (a) Detection principle; (b) far-field focus pattern obtained by simulation^[70]

Fig. 2. Working principle of metasurfaces. (a) Working principle; (b)-(f) intensity distribution on the focal plane when topological charges are 0, 1, -1, 2, and -2, respectively^[71]

Fig. 3. Diffracted beam. (a) Diffracted beams with different topological charges; (b)-(g) interference patterns with 1, -1, 2, -2, 3 and -3 topological charges, respectively^[72]

Fig. 4. Schematic diagram of the spin decoupling metasurface^[73]

Fig. 5. Structure of v-type gold plasmonic metasurface. (a) Schematic diagram of metasurface self-interference; (b) schematic diagram of metasurface design^[75]

Fig. 6. Simulation results of the plasmonic metasurface. (a) Interferograms generated by beams with different OAM; (b) relationship between internal point spacing and topological charge at different z values; (c) relationship between internal point spacing and topological charge at different R₀^[75]

Fig. 7. Structure of an aluminum metasurface. (a) Unit cell of nanoslit antenna; (b) homogeneous nanoslit array ^[77]

Fig. 8. Structure of ultrathin metasurfaces. (a) Spatial arrangement of nanoantennas on the metasurface; (b) SEM image of the metasurface; (c) SEM image of a single L-shaped nanoantenna^[78]

Fig. 9. Experimental results. (a) Experimental procedure; (b) intensity cross section of transmitted light; (c) interference pattern of output beam of left circularly polarized light and spherical wave; (d) interference pattern of output beam of right circularly polarized light and spherical wave^[78]

Fig. 10. Bifunctional reflective metasurface based on helicity. (a) LCP incidence; (b) RCP incidence^[79]