Thin Multispectral Camouflage Absorber Based on Metasurfaces with Wide Infrared Radiative Cooling Window

Abstract

Herein, a hierarchical metamaterial (HMM) is reported to achieve multispectral camouflage for thermal infrared detectors and radar. The HMM consists of a frequency‐selective emitter (FSE) integrated with a microwave absorber (MA). The FSE layer has an average absorptivity of 0.18, 0.85, and 0.18 in the wavelength of 3–5, 5–8, and 8–14 μm, respectively, in the case of the normal incidence. The absorptivity of MA maintains more than 91% (87%) in the broadband of 8–12 GHz (the entire X‐band) up to incident angles of ±40° for TM (TE) polarization. Overall, the average surface emissivity of HMM is 0.25, 0.86, and 0.26 in the infrared broadband of 3–5, 5–8, and 8–14 μm, respectively. The FSE considers infrared camouflage and infrared radiative cooling. The performance of HMM in microwave range remains unchanged, compared to MA structure without FSE layer. From the point of view of thickness, the HMM structure is only 2.34 mm. These excellent performances indicate that the herein described proposed HMM has promising applications in multispectral camouflage fields.

Ultrahigh Extinction Ratio Long‐Wave Infrared Polarization‐Selective Broadband Metamaterial Absorber

“…These designs employ rotationally symmetric patterns to maximize the utilization of incident light energy to obtain polarizationinsensitive broadband or narrow-band absorption. [15,[17][18][19][20] In recent years, polarization imaging and detection techniques have developed booming, [21,22] and polarization-selective absorption has become increasingly important. Generally, the spontaneous emission and reflection of objects in the infrared band have polarization characteristics.…”

Wafer‐Scale 200 mm Metal Oxide Infrared Metasurface with Tailored Differential Emissivity Response in the Atmospheric Windows

“…In particular, lightweight, low volume, and large-area treatments that are able to control the spectral emissivity profile of surfaces, have been shown to be of interest for thermal management through radiative cooling, [23][24][25] spectrally selective detectors and emitters, [8,[26][27][28][29][30][31][32] infrared imaging, [28,33,34] polarization control, [35][36][37] sensing, [38][39][40][41][42] and defense. [43][44][45][46][47][48][49][50][51][52] Engineering of the electromagnetic properties of materials over the different bands in mid-IR is therefore of considerable interest for controlling the reflectivity, absorption, and emissivity spectral response.…”

Multimode‐Assisted Broadband Impedance‐Gradient Thin Metamaterial Absorber

“…[12][13][14][15][16][17][18] Since the first attempt with perfect absorption realized based on metamaterials, [19] the interested operation range of MAs has been extensively expanded from microwave, terahertz (THz), and infrared to visible light. [16][17][18][19][20][21][22][23][24] Nevertheless, the early attempt suffers from a series of drawbacks, such as narrowband, and polarizationand angle-sensitive performance, which significantly limit their real-world applications. To solve the earlier issues, researchers have developed several strategies to achieve absorbers with multiband, broadband, wide-angle, polarization-insensitive, and even tunable characteristics.…”