Wide-angle and polarization-insensitive broadband absorber based on multilayer metal-dielectric films

Plasmonic nanostructures and metamaterials exhibit strong light absorption. This paper proposes an ultra-thin broadband absorber (total thickness <180nm) based on Al₂O₃/Au multilayer film. By precisely controlling the thickness of each layer to achieve multi-level Fabry-Pérot resonance, efficient absorption is achieved in the UV-visible light band of 150-500nm, with a peak absorption rate of 99.9%. This design combines the characteristics of a wide angle of 0°-60° and polarization insensitivity, a TE/TM difference of <5%, and does not require complex nano-processing, providing a new solution for the development of low-cost optoelectronic devices. Studies have shown that local electric field enhancement and resonant mode coupling in ultra-thin dielectric layers are the key to excellent performance. This simple and scalable design provides an efficient solution for photovoltaics, photoelectric detection and other fields.