Abstract
The absorption and reflection of electromagnetic waves by various particles in the earth’s atmosphere allow the passage of only certain electromagnetic wavelengths to reach the ground, called Earth’s atmosphere transparent window. In this study, perfect absorption was theoretically obtained in the range of near- and mid-infrared earth’s atmospheric transparency window using a simple absorber with metal-dielectric-metal structure. The numerical simulations showed the average absorption to reach 96.2% at wavelengths from 2000 to 6000 nm. Also, the broadband absorption was noticed and attributed to combined physical mechanisms, such as anti-reflection effect, localized surface plasmon polariton, propagating surface plasmon polarization, Fabry–Pérot cavity and slow light mode. Meanwhile, the proposed absorber displayed simple-structure, low-cost, wide-angle, and polarization-independent. In sum, the proposed absorber might be useful for future applications related to atmospheric transparency window, such as remote sensing, energy harvesting, infrared detection, and stray light elimination.
Highlights
Perfect absorbers (PA) based on metamaterials have been the subject of intensive research in recent years owing to their various potential applications in infrared stealth, daytime radiative cooling, solar energy, and thermal imaging, among others [1,2,3,4,5,6,7,8,9]
Polymethyl methacrylate (PMMA) with a thickness of 30 nm is coated on the upper surface of the TiO2 layer using spin-coating method as the photoresist
A Earth's atmospheric transparency window (ATW) metamaterial absorber consisting of simple MDM structure covered by MgF2 coating was successfully obtained by finite difference time domain (FDTD) methods and optimized by particle swarm optimization (PSO)
Summary
Perfect absorbers (PA) based on metamaterials have been the subject of intensive research in recent years owing to their various potential applications in infrared stealth, daytime radiative cooling, solar energy, and thermal imaging, among others [1,2,3,4,5,6,7,8,9]. Previous studies have focused on the use of multilayered structures consisting of alternating layers of flat metal and dielectric plates as common infrared absorbers. The reason for this has to do with nature of the structure, which could broaden the absorption bandwidths [20,21]. Yu et al reported a broadband plasmonic absorber for mid-infrared ATW based on metal–spheres–metal–insulator–metal structure with high absorption of 90% from 3000 to 6000 nm [18]. The proposed absorber showed numerous excellent characteristics, including simultaneous ultra-broad and perfect absorption performances, low cost, and simple fabrication Such a MDM structure would be useful for the construction of perfect absorbers for ATW with extremely simple designs. According to the actual preparation process and structural parameters, we fine-tuned some of the optimized structural parameters to adjacent integers, the optimal parameters were determined as: p=400 nm, w=320 nm, t1=600 nm, d=10 nm, t2=270 nm, and t3=100 nm
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