The efficient control of optical light at the nanoscale level attracts marvelous applications, including thermal imaging, energy harvesting, thermal photovoltaics, etc. These applications demand a high-bandwidth, thermally robust, angularly stable, and miniaturized absorber, which is a key challenge to be addressed. So, in this study, the simple and cost-effective solution to attain a high-bandwidth nanostructured absorber is demonstrated. The designed nanoscale absorber is composed of a simple and plain circular ring of nickel metal, which possesses many interesting features, including a miniaturized geometry, easily fabricable design, large operational bandwidth, and polarization insensitivity, over the previously presented absorbers. The proposed nanoscale absorber manifests an average absorption of 93% over a broad optical window from 400 to 2800 nm. Moreover, the detailed analysis of the absorption characteristics is also performed by exciting the optical light’s various incident and polarization angles. From the examined outcome, it is concluded that the nanostructured absorber maintains its average absorption of 80% at oblique incident angles in a broad wavelength range from 400 to 2800 nm. Owing to its appealing functionalities, such as the large bandwidth, simple geometry, low cost, polarization insensitivity, and thermal robustness of the constituting metal, nickel (Ni), this nano-absorber is made as an alternative for the applications of energy harvesting, thermal photovoltaics, and emission.

Broadband metasurface-based devices are essential and indispensable in modern wireless communication systems. This paper presents an ultra−wideband and wide incident angle reflective cross−polarization converter metasurface. The unit cell of the proposed structure is a 45° rotated anisotropic meta−sheet developed by cutting the rhombus−shaped patch from the central part of the square patch. The unit cell’s top structure and ground blocking sheet are made of copper, whereas a dielectric substrate (FR−4) is used as an intermediate spacer between them. The unit cell thickness is minimal compared to the operating wavelength ($1/14{\mathsf{\lambda }}_{\circ }$, where ${\mathsf{\lambda }}_{\circ }$ is the wavelength of the starting frequency of 13 GHz of the operating band). The proposed structure efficiently converts linearly polarized waves into their orthogonal component, with a polarization conversion ratio of (PCR > 90%) over a broad frequency spectrum of 13 GHz to 26 GHz. The physical origin of polarization conversion is also depicted using surface current distribution plots. An ultra−wideband and highly efficient polarization conversion (above 90%) is achieved with the help of strong electromagnetic resonance coupling between the upper and lower layer of the metasurface. This kind of ultra−wideband polarization conversion metasurface can be employed in satellite communication, radar cross−section reduction, and navigation systems.