Fig. 1. Electromagnetic wave and infrared photodetection（a）electromagnetic wave spectrum^［1］；（b）visible（top）and infrared images（bottom）of the author captured under illumination；（c）visible（top）and infrared images（bottom）of the author captured in darkness

Fig. 2. Schematic view of the basic structure of a thermal detector ^［2］

Fig. 3. Specific detectivity of various infrared detectors as a function of wavelength^［3］.

Fig. 4. Spectrally selective infrared thermal detectors achieved using Fabry–Pérot cavity（a）schematic diagram of the fundamental structure ^［10］；（b）VO_x inserted into the Fabry–Pérot cavity as a thermal sensitive material ^［65］；（c）thermal sensitive material located at the top of cavity ^［66］；（d）miniaturized spectrometer based on Fabry–Pérot cavity ^［67］

Fig. 5. Spectrally selective bolometers based on metal-insulator-metal metasurfaces.（a）Si bolometer integrated with Au-Si₃N_x-Au-Ti metasurface（left）and the absorption spectra（right）for widths of 1.25 μm（dash dot line），1.5 μm（dot line），1.75 μm（dash line）and 2.0 μm（line），respectively^［81］.（b）VO_x bolometer integrated with polarization sensitive metasurface（top），and the corresponding absorption spectra and voltage spectral responsivity（bottom）under TE and TM polarizations^［68］.（c）a-Si bolometer integrated with Au-Al₂O₃-Au metasurface（left）and the corresponding absorption spectrum（right）^［82］.（d）Si_xGe_yO_1-x-y bolometer integrated with Al array metasurface，and the specific detectivity vs. modulation frequency（right）^［83］.（e）Au-SiNx-Au bolometer integrated with polarization insensitive metasurface，with top Au layer serving as thermal sensitive material（left），and the scanning image of soldering iron by the fabricated single pixel bolometer（right）^［70］.

Fig. 6. Spectrally selective bolometer utilizing metasurfaces（a）carbon nanotube bolometer integrated with rhombic Ag metasurface（left），and the comparison of responsivity between plasmonic and non-plasmonic device（right）^［85］；（b）bolometer integrated with metallic grating metasurface，and the near infrared spectra of different structure sizes^［86］；（c）bolometer integrated with hook-like Au metasurface（left），and the corresponding extinction spectra（top right）and voltage spectral responsivity（bottom right）^［69］；（d）bolometer integrated with metallic cross metasurface（top left），and the measured TCR（top right），photocurrent-voltage characteristic（bottom left），and the measured photocurrent vs. modulation frequency（bottom right）^［87］

Fig. 7. Spectrally selective thermal detector utilizing Seebeck effect（a）spectrally selective thermal detector integrated with metallic holes array metasurface（left），and the responsivity of varying geometrical parameters vs. wavelength（right）^［89］；（b）spectrally selective thermal couple detector with Fabry–Pérot cavity（left），and specific detectivity vs. wavelength（right）^［64］；（c）thermal couple detector integrated metallic cross metasurface for gas sensing（left），and the normalized voltage spectral responsivity（right）^［90］；（d）poly-Si thermal couple detector integrated with mesh grid metasurface（left），and the absorption spectra for the nanostructures with different geometric sizes（right）^［91］

Fig. 8. New types of spectrally selective thermal couple detector utilizing metasurfaces（a）Carbon nanotube integrated with Al hollow ring metasurface（top），and the corresponding reflection spectrum（bottom left），and comparison of detectivity between patterned and unpatterned devices（bottom right）^［92］；（b）graphene hot-carrier Seebeck detector integrated with asymmetric hexagonal holes array metasurface（top），and absorption spectra and electric field distributions（bottom）^［93］；（c）asymmetric single metal thermal couple detector（top）and the spatial distribution of photocurrent with spot position（bottom）^［94］

Fig. 9. Near-infrared and mid-infrared pyroelectric detectors integrated with metasurfaces（a）pyroelectric detectors integrated with random Ag cube and the simulated thermal impulse response（top），and the reflection spectra and photovoltage spectra of several different detectors（bottom）^［95］；（b）pyroelectric detectors integrated with metal-insulator-metal cross metasurface（top），and the absorption and photovoltage spectra（bottom）^［96］；（c）pyroelectric detectors for multi-wavelength detection integrated with Al-Al₂O₃-Al cylinder metasurface（left），and the absorption and photovoltage spectra（right）^［79］

Fig. 10. pyroelectric detectors integrated with metasurfaces for gas sensing and long-wave infrared detection（a）spectrally selective pyroelectric detectors integrated with disk array metasurface（top），and the absorption spectrum（bottom）^［80］；（b）pyroelectric detector integrated with holes array metasurface（top），and the comparison of output voltage between patterned and unpatterned device（bottom）^［97］；（c）a scanning electron microscope image and unit cell of metasurface（top），and absorption and photovoltage spectra（bottom）^［98］