Hierarchical metamaterials for laser-infrared-microwave compatible camouflage

In this paper, a hierarchical metamaterial (HMM) is reported to achieve compatible camouflage for laser, thermal infrared detectors, and radar. The HMM consists of an all-metallic metasurface array (AMMA) integrated with a microwave absorber. The top AMMA plays two roles. First, the gradient metasurface can reduce the specular reflection at the laser wavelength of 1.06 mu m to less than 5% by tailoring the wavefronts and redirecting the reflected energy to non-specular angles. Second, the AMMA acts as an infrared shielding and microwave transparent layer, ultralow surface emissivity (similar to 5%) in the infrared atmosphere window of 3-5 mu m and 8-14 mu m can be realized, and incident microwave can perfectly pass through the top AMMA and then be absorbed by the bottom microwave absorber. The absorption efficiency is over 90% in the broadband of 7-12.7 GHz up to incident angles of 40 degrees for both TE and TM polarizations. These excellent performances indicate that our proposed HMM has promising applications in multispectral camouflage fields. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement