Optically transparent frequency-selective thermal radiator based on metamaterials

Metamaterials provide amazing opportunities for developing frequency selective radiation because of their unique electromagnetic resonance properties. However most frequency-selective thermal radiation metamaterials currently do not have an optical transparency property, which prevents them from being used in some special occasions. Here, an optically transparent frequency-selective thermal radiator is designed and fabricated using the metallic-like properties of ITO. The emissivity of the metamaterial in the atmospheric transparent windows (3.0-5.0μm and 8.0-14.0μm) is less than 0.1, while the emissivity outside the windows (5.5-7.6μm) is very high, thus achieving strong thermal radiation efficiency. Finally, the thermal radiation power of frequency-selective thermal radiator, low-emissivity coatings, and black body was analyzed using the thermal radiation model. Compared to traditional low-emissivity coatings, the advantage of frequency-selective thermal radiators is that it provides an efficient thermal radiation window for the target, further enhancing its infrared stealth capability through radiative cooling.