Wide-angle, wide-band, polarization-insensitive metamaterial absorber for thermal energy harvesting

Abstract

We propose a wide-band metamaterial perfect absorber (MPA), using the coupling in the near-field of a quadruple split-ring resonator concentric with crossed ellipses. We designed the MPA with a metal–insulator-metal (MIM) structure for use in thermal energy harvesting. A gradient-based optimization approach was carried out to maximize the absorption of infrared (IR) radiation around 10 μm. Owing to the near-field coupling of resonators with optimal design parameters, the peaks of the absorption responses approach each other, thus broadening the overall bandwidth with almost unity absorptivity. The proposed design has a resonance at 10 μm resulting from magnetic polaritons (MPs) and thus maintains high absorption above 99% up to a range of incident-angles greater than 60° and exhibits a polarization-free behavior due to symmetry. When the optimal design was numerically examined to fabrication tolerances, it showed negligible sensitivities in the absorptivity with respect to design parameters. The strong electric field enhancement inside the split-ring gaps and between the ends of the cross arms and the surrounding ring enables designing MIM diodes to rectify the harvested thermal radiations at 288 K. MIM diodes can be built by the deposition of thin insulators to sit in these gaps. The MIM diode and MPA work together to harvest and rectify the incident IR radiation in a manner similar to the operation of rectennas. The MPA outperforms the traditional nano-antennas in impedance matching efficiency because of its higher resistance. Also, its dual-polarization reception capability doubles the rectenna efficiency. Our proposed MPA retained absorptivity more than 99% when coupled with MIM diodes whose resistances are in the range of 500 Ω–1 MΩ.

Review of Broadband Metamaterial Absorbers: From Principles, Design Strategies, and Tunable Properties to Functional Applications

“…For example, a BMA using multiple discs of various sizes were studied, [344] allowing the formation of broad-band of 2000 nm, with the disadvantage that its absorption was experimentally relatively low, less than 50%. Broadband absorption for thermal energy harvesting was demonstrated by employing a quadruple SRR concentric with the cross-shaped ellipse, [365] which could achieve near-perfect absorption in the IR region. An ultra-broadband and polarization-insensitive MA operated at the MIR region using nine different-sized squarepatch resonators were designed.…”

Broadband Metamaterial Solar Absorbers Based on the Earth First-Rate Temperature-Insensitivity Metals for High Temperature Energy Harvesting

“…The emerging field of artificially engineered materials, known as metamaterials, has attracted much attention in the last years for potential use in thermophotovoltaic systems (TPVS) and solar thermal approach [9][10][11][12][13][14]. By demonstrating interesting electromagnetic properties not found in naturally occurring materials, the metamaterial solar absorbers (MSA) have opened a new avenue for solar energy harvesting.…”

Flexible Broadband Metamaterial Perfect Absorber Based on Graphene-Conductive Inks

“…In 2008, the so-called metamaterial perfect absorber (MPA) was devised by Landy et al [4], which showed a very high absorption but was very thin. The MPAs have high potential for a variety of applications such as for photodetectors [5,6], sensors [7,8], energy harvesters [9,10], and stealth technology [11][12][13]. Since then, the commercial uses of MPAs for healthcare and civilian demands have induced more intensive research on them and their applications.…”

“…MPAs can be obtained with a sandwiched multilayer of a periodically-arranged metallic pattern, dielectric-spacer layer, and continuous metallic plate [10,13]. Most of the recent MPAs are hard or stiff, since they are usually fabricated with a hard dielectric layer such as FR4 [4] or silicon [14], which also makes the absorption behavior fixed.…”