A Metamaterial Absorber Based on Particle Swarm Optimization Suitable for Earth’s Atmospheric Transparency Window

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.