An Optimal Ultra‐Thin Broadband Polarization‐Independent Metamaterial Absorber for Visible and Infrared Spectrum Applications

ABSTRACT This paper presents the design and study of an extremely thin, wideband, and polarization‐insensitive metamaterial absorber (MMA) tailored for applications in the visible and infrared (IR) spectral ranges. The proposed MMA introduces a diamond‐shaped resonator setup, achieves high absorption efficiency beyond 90% across a wide wavelength range from 331.64 to 2163.1 nm. The average bandwidth of absorption is 95.64%, having the highest absorption rate of 99.039% witnessed at 511.47 nm. The unit cell of the absorber is condensed and designed to cover the visible optical range, along with the near and short infrared optical windows. Aluminium nitride (AlN) is used as the substrate, while nickel (Ni) serves as both the ground and resonator layer material, contributing to the MMA's durability and thermal stability. As the absorber is symmetric in design, it ensures polarization independence, with steady absorption performance maintained at oblique angles of incidence up to 75°. Comprehensive parametric simulations were performed, examining elements such as surface current distribution, layer thicknesses, different substrate materials and variations in permittivity and permeability, all of which demonstrate the MMA's robustness and adaptability for various applications and by covering a wide spectral range and exhibiting flexibility to polarization and incident angle variations, this absorber offers an effective platform for environmental monitoring, IR detection, and solar energy harvesting.