Femtosecond laser fabrication metasurface emitter for multispectral camouflage.

The powerful electromagnetic capability of a metasurface makes it a good candidate for thermal emission manipulation toward promising infrared (IR) camouflage and thermal management technology. Here, a metasurface-based infrared is fabricated to achieve multispectral camouflage as well as radiative cooling simultaneously. Cross-scale processing on metal-dielectric composite films is successfully achieved by femtosecond laser direct writing (FsLDW), which is proven to be an efficient and feasible technique in metasurface fabrication. The prepared emitter exhibits low emissivity (ɛ_3-5 μm= 0.32, ɛ_8-14 μm= 0.31) in atmospheric windows but high absorption in 10.6 μm so that it can effectively evade the tracking of infrared detectors and laser radars. Besides, the emitter also has high emissivity in the undetected band (_ɛ5-8 μm= 0.66) to dissipate possible heat accumulation. The proposed metasurface design and fabrication method empowers new ideas for the generation of optical devices toward multispectral camouflage and radiative cooling compatibility.