An Infrared Metamaterial Broadband Absorber Based on a Simple Titanium Disk with High Absorption and a Tunable Spectral Absorption Band

Abstract

A metamaterial absorber is proposed that functions in the medium‐ (3–5 µm) and long‐wavelength (8–12 µm) infrared (medium‐wavelength infrared, MWIR, and long‐wavelength infrared, LWIR, respectively) regions. The proposed design, which consists of periodic cells, can be tuned to achieve single‐band or dual‐band light absorption by changing the periodicity of the structure. Each cell forming the metamaterial absorber consists of a bottom metal plate (Al), a top metal disk (Ti), and an intermediate dielectric medium (Si or ZnS) in which a metal disk (Ti) is embedded. For a period of 0.85 µm, the absorber achieves broadband absorption in the LWIR region, with an average absorption of 92.1%. Further, the absorber shows acceptable tolerance to irradiation at oblique incidence. For a period of 2 µm, a peak absorption of 99.05% is achieved in the MWIR region, thereby providing dual‐band absorption. Tuning the periodicity of the structure enhances the localized surface plasmon resonance, with the absorption mechanism explained by establishing an equivalent parallel LC circuit. The absorption properties demonstrated by the proposed metamaterial absorber are promising for thermal imaging and infrared spectroscopy.

Metamaterial ultra-wideband solar absorbers based on a multi-layer structure with cross etching

“…In 2020, Liang et al . 11 further proposed a metamaterial absorber that could work in the mid-infrared (3000–5000 nm) and long infrared (8000–12 000 nm) wavelengths, achieving 92% absorption in the two regions. In the visible light band, Chi et al .…”

“…In 2013, Liang et al 10 designed a metamaterial absorber with a two-dimensional pyramid structure that achieved near-perfect absorption in the band of 1000-1400 nm. In 2020, Liang et al 11 further proposed a metamaterial absorber that could work in the mid-infrared (3000-5000 nm) and long infrared (8000-12 000 nm) wavelengths, achieving 92% absorption in the two regions. In the visible light band, Chi et al 12 designed a metamaterial absorber with an overall absorption rate of more than 70% in the wavelength range of 400-2000 nm.…”

Broadband absorber based on metamaterials

“…So far, the absorbers investigated have absorption ranges ranging from visible light to microwave frequencies. After a large number of scholars researched the visible light band, the absorber band's focus switched to the near-infrared and midinfrared regions [2][3][4][5][6][7][8] .…”

Design of an optimized multilayer absorber into the MWIR and LWIR bands

“…To enhance efficiency, design of appropriate multiband IR absorbers is of current interest. A number of approaches have been proposed recently, based on various surface layers including metamaterials, 11‐20 surface‐structured silicon, 21 vertically aligned carbon nanotubes, 22 electrosprayed carbon‐based coatings, 23 and so on.…”

“…Alternative approaches make use of pyramidal‐shaped resonant elements 14‐16 . Some recent promising designs 17‐20 are based on one or more thin and highly resistive metal layers of arrays of titanium disks or rings above the dielectric spacer; the relatively high resistance of titanium results in a low‐Q factor of the surface resonances that helps to achieve a broader absorption band, while tuning is possible via modification of the disk geometry. However, the above designs exhibit a significant degree of fabrication complexity.…”