Fabry-Perot-resonator-coupled metal pattern metamaterial for infrared suppression and radiative cooling

The most intuitive approach for infrared stealth, namely, the indiscriminate suppression of thermal radiation, is often at the risk of overheating the target. Spectrally selective metamaterials may solve this problem by satisfying radiative cooling as well as infrared suppression. Therefore, we have designed and fabricated a broadband metamaterial by depositing a Fabry-Perot (F-P) resonator on top of a metal pattern. The composite structure has two absorption peaks, one originating from F-P resonance, the other from the magnetic resonance of the metal pattern, and they can be merged into the 5∼8 µm range through optimization. According to Kirchhoff's law, this results in high emissivity in the 5∼8 µm range (the best choice of nonatmospheric-window ranges) and low emissivity in the 3∼5 µm and 8∼14 µm ranges (the two atmospheric windows), satisfying both infrared suppression and radiative cooling. Energy dissipation distributions indicate apparent coupling of F-P resonance and magnetic resonance, but these two resonances are stronger at their respective intrinsic wavelengths. This paper reveals an alternative method for infrared suppression with radiative cooling, which is also meaningful in the design of broad/multiband absorbers.