# Broadband Plasmonic Metamaterial Optical Absorber for the Visible to Near-Infrared Region
###### Abstract  
An oblique angle and polarization insensitive metamaterial absorber (MA) are highly desired for the visible and infrared optical applications like, wave energy harvesting, optical filters, and detecting thermal leaks and electrical defects. In this paper, a multi-layered MA consisting of two layers of tungsten resonators on a silicon dioxide substrate, coated with additional SiO\({}_{2}\) materials is investigated. The unit cell size of the MA is 0.5\(\times\) 0.5\(\times\) 0.8\(\times\) 0.8\(\times\) 0.8\(\times\) 0.  
absorbers (MPA) for the visible and infrared spectrum has recently attracted much research attention. MPAs can be applied to manipulate light at a specific range of frequencies or wavelengths by modifying their resonance properties. Most of the MPAs intended for the visible ranges are bound by a narrow absorption spectrum, which limits their applications to solar resonators and thermal emission manipulations. Applications like solar energy converters, thermal emitters, and artificial colors with polarization and angle-insensitive properties make wideband absorbers particularly appealing. Numerous techniques for extending the absorption band have been developed as a result of research on broadband absorbers, including periodic array [9], plasmonic ab-sorber structure [20], metamaterial transmission line absorber [21] phase-changing mate-rial-based tunable absorber [22; 23] Nanoarchitectonics PMA [24], carbon nanotube ab-sorber [24]. Most conventional approaches mainly focus on a common absorption mechanism that involves coupling many resonances with a broad wavelength range excited by variously sized metallic resonators in the structures. Based on the general principle of di-polar management via structural reconstruction of kirigami-inspired meta-architecture, a transformable metamaterial has been presented in the article [25] for Adaptable Invisibility Management. They used three enantiomers with various geometries distinguished by the folding angle to exhibit reconfigurable invisibility management with a wealth of EM functions and a broad tuning range. The meta-architecture, which was created on a transparent substrate, was intended to operate between 4 and 16 GHz. Industrial technologies have difficulty producing structurally complex absorbers because of their complex structures and paresis measurements. Thus, an absorber with a compact size, broad absorption spectrum, polarization insensitive, high incident angle stable, simple fabrication, and low cost is required for optical window applications. Besides, prevention of incident light reflection is another challenge for optical absorbers. The concept of employing silicon dioxide (SiO\({}_{2}\)) can overcome this limitation. The SiO\({}_{2}\) has the properties of suppressing incident light reflection to create a wideband absorber. Also, SiO\({}_{2}\) laminating can prevent metal resonators from oxidization. In addition, Tungsten (Tu) is preferable for metal resonators due to its high intrinsic loss and impedance-matching properties with free space in optical wavelength. Tungsten can withstand high temperatures thanks to its high melting point, making it ideal for thermo-photovoltaic and other high-temperature applications [23]. This paper proposes a wideband, efficient, and straightforward novel multilayer MA for solar application in the optical and near-infrared spectrum. A layer of SiO\({}_{2}\) on top works as an antireflection coating, protecting from rusting of the metal Tu layer and improving absorption. The average absorption was 92% across the optical and near-infrared spectrum, covering from 400 nm to 2400 nm wavelength. The MA is also polarization insensitive and incidence angle insensitive up to 45\({}^{\circ}\). Additionally, the unit cell's photon conversion efficiency has been calculated regarding A\({}_{\text{AM1.5}}\), with the MA obtaining an A\({}_{\text{AM1.5}}\) of 90.76%. A brief study of the magnetic and electric field, charge distributions, and current density have also been presented.