Fig. 1. Dispersive spectral imaging metasurface. (a) Broadband anomalous reflection metasurface for spectral demultiplexing^[58]; (b) dispersive metasurface for off-axis focusing^[62]; (c) aberration corrected dispersive metasurface for off-axis focusing^[63]; (d) compact folded spectrometer with metasurfaces^[64]; (e) optical field imaging by metasurface array with transverse dispersion^[57]

Fig. 2. Filter-type spectral imaging metasurface. (a) Plasmonic metasurface with nanoslit structure for spectral filtering^[68]; (b) multispectral imaging using metasurface with nanohole array^[69]; (c) tunable metasurface based on GST materials^[67]; (d) high-Q metasurface array for molecular absorption spectroscopy^[65]; (e) cascaded metasurfaces for multispectral imaging^[66]; (f) multispectral imaging with multi-resonant metasurface using CODE algorithm^[77]

Fig. 3. Photonic crystal metasurface. (a) Photonic crystal spectrometer^[93]; (b) single-photon spectrometer with integrated photonic crystal filters^[94]; (c) multispectral imaging with on-chip spectral sensors based on photonic crystal slabs^[95]

Fig. 4. Spectral imaging metasurface by computationally reconstructed. (a) Tunable graphene metasurface spectrometer^[96]; (b) multispectral imaging metasurface with free-form unit cells^[97]; (c) anti-spoofing face recognition based on hyperspectral imaging metasurface^[98]; (d) broadband encoding stochastic hyperspectral imaging based on deep learning^[99]; (e) hyperspectral polarization imaging empowered by machine learning^[100]

Fig. 5. Artificial intelligence empowered spectral imaging metasurface. (a) Linear least squares regression algorithm for identifying fingerprints of biomolecules^[109]; (b) deep neural network for recognition and detection of biomolecules in metasurface microfluidic devices^[108]; (c) multispectral imaging via genetic algorithm combined with compressed sensing^[111]; (d) hyperspectral imaging based on deep neural network^[112]

Fig. 6. Passive depth sensing metasurface. (a) Binocular meta-lens^[49]; (b) monocular meta-lens for polarization-multiplexed imaging^[117]; (c) spider-inspired monocular dual-defocus meta-lens^[119]; (d) depth sensing metasurface based on PSF encoding^[120]; (e) achromatic meta-lens array for light field imaging^[122]; (f) meta-lens array for light field imaging and point cloud projection multiplexing^[123]

Fig. 7. Active depth sensing metasurface. (a) 3D reconstruction based on metasurface point cloud projection^[124]; (b) depth sensing metasurface with holographic point cloud pattern encoding^[130]; (c) metasurface with 180° field-of-view point cloud projection^[131]; (d) metasurface- and PCSEL-based structured light for facial recognition^[132]; (e) beam steering with meta-lens array for distance detection^[133]; (f) 3D imaging using super-dispersion metasurface^[134]; (g) multi-wavelength structured light projection for 3D imaging^[135]

Fig. 8. Metasurface for edge detection. (a) One-dimensional spatial differentiation for edge detection^[141]; (b) edge detection based on polarization-entangled photon source^[142]; (c) second-order differentiation metasurface for biological cell imaging^[145]; (d) metasurface differentiator with tailored polarization responses^[146]

Fig. 9. Metasurface for edge detection. (a) Metasurface spatial differentiator with oblique incidence^[147]; (b) edge detection metasurface based on quasi-BIC mode^[148]; (c) edge detection metasurface under incoherent broadband illumination^[150]; (d) long-wave infrared metasurface differentiator optimized by inverse design^[151]; (e) broadband high order spatial differentiator based on meta-lens^[152]

Fig. 10. Artificial intelligence empowered multi-dimensional feature detection of metasurface. (a) Edge enhanced depth perception with binocular meta-lens^[157]; (b) large depth-of-field imaging with multi-scale convolutional neural networks^[158]; (c) non-iterative metasurface holography design method based on GAN and VAE^[159]

Fig. 11. Recent advances in frontier applications of metasurface. (a) Near-infrared silicon-based meta-lens with diameter of 80 mm^[160]; (b) all-glass large-aperture meta-lens with diameter of 100 mm^[161]; (c) metasurface solar optical reflector for spacecraft thermal protection layers^[166]; (d) metasurface-enabled underwater wireless optical communication^[162]