Broadband and Polarization‐Insensitive Plasmonic Solar Absorber Using Simplified Nickel‐Based Metamaterial Architecture

Thermal imaging, thermal photovoltaics, energy harvesting, and other interesting applications are implemented through the effective control of optical light at the nanoscale level. One of the main challenges to be addressed is the need for a thermally resistant, miniaturized, high bandwidth, and angularly stable absorber for these applications. Thus, in this work, a nanostructured absorber is presented as a cost-effective and simple solution for attaining a wide bandwidth. The design of the nanoscale absorber is made up of a simple hash of nickel (Ni) metal which shows interesting features over the previ- ously presented absorbers, such as a large operational bandwidth, a miniaturized geometry, an easily fabricated design, and polarization insensitivity. For the broad optical window extending from 400 to 4000 nm, the hash nanoscale absorber (HNA) has an average absorption of 93%. Furthermore, the absorption characteristics are thoroughly analyzed by stimulating the optical light at different incidence and polarization angles. The results of the analysis show that the nanostructured absorber maintains its average absorption of 80% at oblique incidence angles throughout a broad wavelength range of 400 to 4000 nm. An interference theory based on a multi-reflection model is introduced to compare the consistency between the simulated and analytical absorption characteristics. The thermal robustness, low cost, simple geometry, large bandwidth, and polariza- tion insensitivity of the nickel (Ni) constituent make this nano-absorber an attractive alternative for thermal photovoltaics, energy harvesting, and emission applications.