Fig. 1. Physical mechanism and phase modulation of passive metasurface. (a) (b) Resonance metasurface^[6]; (c) (d) propagation metasurface^[16]; (e) (f) geometric metasurface^[17]

Fig. 2. Meta-based compact system. (a) Infrared imaging system based on single-layer metalens^[20]; (b) compact folded spectrometer^[21]; (c) compact microscope based on metasurface integrated CMOS^[22]; (d) shared-aperture multifunctional interleaved geometric-phase metasurfaces^[23]

Fig. 3. Metasurface-based point cloud projector. (a) Metasurface-based Dammann grating with large field of view^[42]; (b) full-space random point cloud projector with metasurface^[43]; (c) large area pixelated random point generation^[44]; (d) light deflection controlled by VCSEL-integrated metasurface^[45]; (e) beam splitter based on VCSEL-integrated metasurface^[46]; (f) metasurface-based full-space dot array for three-dimensional imaging with large field of view^[47]

Fig. 4. Actively tunable metasurface based on TCO material for beam steering. (a) Electric gated diffraction gratings with ITO and the relationship between the steering angle and the gate bias^[50]; (b) ITO-based gap-plasmon metasurfaces for reflection phase and polarization control^[51]; (c) dual-gated metasurfaces with ITO and the relationship between the steering angle and the gate bias^[52]; (d) ITO-based plasmonic resonator array and the relationship between the steering angle and the gate bias^[53]; (e) all-solid-state SLM with ITO-based metasurface for 3D imaging^[54]

Fig. 5. Actively tunable dielectric MQW metasurface. (a) MQW metasurface with double slit patterns^[56]; (b) LED-integrated metasurface for beam steering^[57]

Fig. 6. MEMS-integrated metasurfaces for beam steering. (a) Suspended silicon metasurfaces^[58]; (b) semisolid micromechanical beam steering system based on MMLA^[59]; (c) metasurface-enhanced beam steering system combined with AOD^[60]

Fig. 7. (a) Actively tunable metasurfaces with liquid crystal approach^[61]; (b) phase-change material^[62]

Fig. 8. Light-field 3D imaging with metalens array. (a) 3D single-particle tracking based on multifunctional metalens array^[66]; (b) achromatic metalens array for full-colour light-field imaging^[67]; (c) double-layers metasurfaces for quantitative phase gradient microscopy^[68]; (d) aberration-corrected 3D positioning with metalens array^[69]; (e) large depth of field light-field imaging system enabled by double focus metalens array based on spin multiplexing^[70]; (f) metalens array combined the structured light and light-field technique for depth perception in complex environment^[71]

Fig. 9. Metasurface-based PSF engineering technique for 3D imaging. (a) Depth from defocus based on bifocal metalens^[72]; (b) extreme dispersion of metalens for 3D reconstruction^[73]; (c) DH-PSF plasmonic metasurfaces for 3D positioning^[74]; (d) DH-PSF dielectric metasurfaces for 3D imaging^[75]; (e) DH-PSF metasurfaces based on spatial multiplexing for large depth imaging^[76]; (f) single-shot 3D spectral imaging based on metalens array^[77]