Fig. 1. Huygens’ metasurfaces. (a) Illustration of the physical mechanism of the Huygens’ metasurfaces^[93]; (b) Metallic Huygens’ metasurfaces^[51]; (c) All-dielectric Huygens’ metasurfaces^[92]

Fig. 2. Multi-layered reflectionless metasurfaces. (a) ABA-type metasurface units and the underlying mechanism^[59]; (b) ABA-type reflectionless metasurfaces for refracted wave manipulation^[87]

Fig. 3. Brewster metasurfaces. (a) The underlying physics of Brewster metasurfaces and their applications for reflectionless manipulation of refracted waves^[53]; (b) The design and broadband reflection property of optical Brewster metasurfaces^[54]

Fig. 4. Wide-angle reflectionless metasurfaces. (a) Wide-angle reflectionless terahertz metasurfaces for TE waves^[146]; (b) Wide-angle reflectionless microwave metasurfaces for TE waves^[152]

Fig. 5. Broadband reflectionless metasurfaces. (a) Broadband reflectionless microwave metasurfaces consisting of double-turn helix units^[99]; (b) Broadband low-reflection terahertz metasurfaces based on optimization methods^[157]; (c) Ultra-broadband reflectionless microwave metasurfaces consisting of double-layer units^[158]

Fig. 6. Anomalous refraction. (a) Microwave gradient Huygens’ metasurfaces^[51]; (b) Near-infrared gradient Huygens’ metasurfaces^[95]; (c) Terahertz reflectionless gradient coding metasurfaces^[193]

Fig. 7. Polarization manipulation. (a) Terahertz anisotropic metasurface as polarization converter^[72]; (b) Tunable terahertz anisotropic metasurface as polarization converter^[74]; (c) Bianisotropic metasurface as polarization converter^[73]

Fig. 8. Meta-antireflection coatings. (a) Bianisotropic meta-antireflection coating using H-shaped metallic units^[194]; (b) Bianisotropic meta-antireflection coating using S-shaped metallic units^[195]; (c) Meta-antireflection coating for simultaneous reflection elimination and wavefront control^[123]

Fig. 9. Perfect electromagnetic wave absorbers. (a) Resonant metasurfaces for perfect electromagnetic wave absorption^[77]; (b) Non-resonant Brewster metasurfaces for ultra-broadband perfect electromagnetic wave absorption^[56]