Fig. 1. Narrowband metamaterial absorbers. (a)(b) A perfect absorber with a metal/dielectric/metal structure^[14]; (c)(d) a narrowband perfect absorber consisting of metallic cylinder arrays^[15]; (e)(f) an all-dielectric perfect absorber^[24]

Fig. 2. Broadband metasurface absorbers. (a)(b) Multi-wavelength absorbers consisting of structures of different sizes squeezed in one unit^[33]; (c)(d) a broadband absorber based on a 3-layer cross structure with different geometrical parameters^[38]; (e)(f) broadband absorbers based on the slow light effect^[39]

Fig. 3. Broadband absorbers based on multilayer films. (a)(b) A broadband mid-infrared absorber formed by a multilayer BaF₂/NiCr structure^[49]; (c)(d) a broadband visible light absorber formed by a SiO₂/Ti structure^[50]; (e)(f) dual-band absorption in the mid-infrared band realized by zero refractive index of SiO₂ and Berreman mode^[52]

Fig. 4. Tunable mid-infrared absorbers based on metasurfaces. (a)(b) Tunable absorbers based on MEMS^[54]; (c)(d) tunable absorbers based on graphene^[55]; (e)(f) tunable absorbers based on VO₂^[58]

Fig. 5. Modulations of mid-infrared thermal radiation sources. (a)(b) Using photonic crystals constructed by multiple quantum well materials for narrow-band thermal radiation^[64]; (c)(d) using ENZ materials for directional thermal radiation^[80]; (e)(f) a periodically rotating nanorod array and its spin-projected dispersion spectra in the far filed^[85]

Fig. 6. Dynamic modulations of mid-infrared radiation. (a)(b) Using extremely thin carbon nanotube material to achieve an ultra-high-speed dynamic modulation in thermal radiation with the modulation speed up to 1 GHz^[90]; (c)(d) a high-speed and wide-range modulation in thermal radiation by injecting electrons into multiple quantum wells^[88]; (e)(f) using GST to modulate thermal radiation^[92]

Fig. 7. Mid-infrared radiation camouflage. (a) Low-temperature infrared camouflage based on a silver/germanium multilayer in the range of 25 to 250 ℃^[93]; (b) high-temperature infrared camouflage based on thermal cooling and reduced emissivity^[96]

Fig. 8. Adjustable mid-infrared radiation camouflage. (a) Adaptive thermal camouflage based on GST^[98];(b) adaptive thermal camouflage based on graphene^[99]

Fig. 9. Multispectral infrared hybrid camouflage^[100,102]. (a) Scanning electron microscopy images of the device structure; (b) measurements of infrared emissivity spectrum and microwave absorption spectrum; (c) simulated infrared and microwave camouflage performance of a supersonic aircraft; (d) multilayer ZnO/Ge structure and Cu/ITO/Cu metasurfaces; (e) reflection spectra of visible light, mid-infrared band, laser, and microwave

Fig. 10. Mid-infrared detectors assisted by metasurfaces. (a) An on-chip quad-wavelength membrane pyroelectric detector^[108]; (b) a thermopile mid-infrared detector based on a metal cross array^[107]; (c) a mid-infrared graphene detector based on the combination of a metal bull's eye and an optical nanoantenna^[112]; (d) a VO₂ microbolometer based on a grating-type MIM absorber^[109]; (e) a mid-infrared graphene chiral detector^[115]