Ultra-broadband metamaterial absorber in the near-infrared to mid-infrared region

This study presents a metamaterial broadband absorber composed of vertically aligned subwavelength metal–dielectric–metal resonators. It achieves over 90% absorption from 1.7 to 8.8 µm, with an average of 98%, and a near-perfect 99.3% average absorption between 2 and 8 µm. The broadband performance originates from the synergistic enhancement of surface plasmon polaritons and localized surface plasmons. The structure demonstrates excellent wide-angle absorption, maintaining over 90% average absorption up to 58° incidence, with polarization insensitivity. It also exhibits strong resilience to environmental refractive index changes. These advantages make it highly suitable for infrared detection, thermal photonics, energy harvesting, and optical stealth applications.