Broadband perfect absorber based on Ni-Al2O3-Pt metamaterials for near-infrared applications

This paper presents the research of a broadband absorber based on Ni-Al2O3-Pt in the near-infrared spectrum. The absorber follows a metal-insulator-metal (MIM) structure with two square and two circular resonant rings on top of Al2O3 dielectric material and a Pt metal layer at the bottom. The absorption characteristics of an absorber are investigated using the finite-difference time-domain (FDTD) method. Findings indicate that the absorber demonstrates an average absorption efficiency of 91.64% within the operational range of 800–3000 nm, with exceptional absorption exceeding 99% observed over a broad bandwidth of 836 nm. We examine the physical process of broadband absorption through an analysis of the electric and magnetic field distributions. Subsequently, the impact of structural characteristics and material compositions on the absorber’s absorption capabilities is deliberated. Ultimately, effect of the incidence angle in TE and TM polarization on the absorption of the absorber is also studied. It was found, even at an incidence angle of 50 degrees, it can achieve over 80% absorption, indicating its insensitivity to changes in the angle of incidence. The absorber shows promise in the areas of solar energy detection and optical imaging due to its high performance and cost-effectiveness.