Fig. 1. Curved surface working diagram. Generalized derivation of Snell’s law. In the absence of water: for LHCP and RHCP incidence, the metasurface operates in state 1, and the beams are deflected by 20° (green) and 35° (purple), respectively. In the presence of water: the metasurface operates in state 2 for LHCP and RHCP incidence, the electromagnetic wave propagates along the tangent line of the surface, and the spin-decoupled function disappears.

Fig. 2. Schematic diagram of the metasurface unit: (a) front view of the first layer, (b) structured water layer, (c) perspective view. Comparison of (d) S-parameters, (e) epsilon, and (f) refractive index for different water layers. Specific parameters are: L1=1  mm, L2=6  mm, W2=2  mm, h1=0.2  mm, h2=0.8  mm, h3=0.6  mm, h4=0.8  mm, h5=0.2  mm.

Fig. 3. Dimensions of the structure of the eight metasurface units.

Fig. 4. (a) Amplitude and phase diagrams of the eight metasurface units, (b) diagram of the co-polarized reflection phase with Lx for the incidence of linearly polarized electromagnetic wave, and (c) magnitude and (d) phase diagrams of the eight units reflections for the incidence of the circularly polarized electromagnetic wave.

Fig. 5. (a) Phase diagram of the metasurface unit I as the angle of rotation changes; (b) amplitude and phase diagram of the metasurface reflection in the presence of water.

Fig. 6. Calculation process of wavefront modulation on the curved metasurface.

Fig. 7. Phase calculation at the incidence of the circularly polarized wave.

Fig. 8. Phase calculation of beam deflection spin-decoupling.

Fig. 9. Electric field distribution without water at (a) RHCP and (b) LHCP incidence. Electric field distribution with water at (c) RHCP and (d) LHCP incidence.

Fig. 10. Comparison of experimental and simulated far-field. Far-field distribution without water at (a) RHCP and (b) LHCP incidence. Far-field distribution with water at (c) RHCP and (d) LHCP incidence.

Fig. 11. Curved surface-focused phase calculation.

Fig. 12. Curved surface-focused spin-decoupled phase calculation.

Fig. 13. In the state without water, electric field distributions at different cross-sections of the curved structure at the incidence of (a), (b) LHCP and (c), (d) RHCP.

Fig. 14. Electric field distributions at different cross-sections of the planar structure at the incidence of (a), (b) LHCP and (c), (d) RHCP.

Fig. 15. In the state with water, electric field distributions at different cross-sections of the curved structure at the incidence of (a), (b) LHCP and (c), (d) RHCP.

Fig. 16. (a) Physical model of multilayer metasurface, (b) top metasurface, (c) bent metasurface, (d) test environment diagram, and (e) test schematic diagram.

Fig. 17. (a) Resin fabrication process, (b) resin dielectric layer, and (c) metasurface-skin (see Visualization 1).

Table 1. 2-Bit Reflection Phase Corresponding to the Size and Geometric Orientation of the Metasurface Unit under the Circularly Polarized Wave

Table 2. Performance Comparison of the Spin-Decoupled Metasurface