Nanoforest-like Metamaterials for VIS–IR Dual-Band Camouflage

Driven by rapid advances in multispectral detection technologies, conventional single-band camouflage strategies have become increasingly insufficient. Here, a visible-infrared (VIS-IR) dual-band compatible silver-deposited silicon nanoforest metamaterial (AgSNF) is proposed and experimentally demonstrated. The AgSNF is fabricated on silicon (Si) substrates via reactive ion etching (RIE), forming disordered Si nanopillars with normally distributed diameters (d) and heights (h). By depositing a silver (Ag) film on the backside of the substrate through magnetron sputtering, this architecture simultaneously exhibits high absorptivity in the visible (VIS: 400-780 nm) and shortwave near-infrared (SNIR: 780-1100 nm) spectrum, along with high reflectivity within the mid/long-wave infrared atmospheric windows (MWIR: 3-5 μm, LWIR: 8-14 μm), enabling effective VIS-IR dual-band compatible camouflage. Simulations and experimental results demonstrate that the stochastic distribution of Si nanopillars significantly enhances VIS and SNIR absorptivity (reaching up to 0.969 and 0.936, respectively) through multiple scattering and Mie scattering mechanisms. Meanwhile, the backside Ag film (thickness ≥ 40 nm) elevates MWIR/LWIR reflectivity to 0.733/0.595, resulting in a substantial reduction of the apparent radiation temperature to 42.1 °C when the actual surface temperature reaches 65 °C. Compared with conventional multilayer films, MXene coatings, and lithography-dependent metamaterials, the AgSNF architecture avoids complex photolithography processes by leveraging direct Si substrate patterning, while offering enhanced thermal robustness and reduced fabrication cost. This work establishes a scalable platform for multispectral camouflage and demonstrates promising potential for military stealth applications and radiative thermal management systems.