Design and optimization of a graphene-based broadband absorber for enhanced absorption in the visible and near-infrared spectrum

This paper presents the design and optimization of a graphene-based broadband absorber aimed at enhancing light absorption across the visible to near-infrared spectrum. The proposed structure features a metal film array with annular and L-shaped grooves that intensify electromagnetic fields and amplify local surface plasmon resonance. This leads to improved interaction between light and the graphene layer. To achieve optimal performance, the design process involved the use of the particle swarm optimization algorithm. This powerful tool fine-tunes the geometric parameters, including the thickness, length, and width of the grooves, with precision and rigor. The optimized structure, comprising chromium as the metal film and Al₂O₃ and TiO₂ as groove fillers, achieved an average absorption rate of 85.79%, a significant improvement over the initial average absorption of 74.33%. This design not only demonstrates substantial potential for applications in photonics, sensing, and energy harvesting but also offers an effective solution for broadband absorbers with high efficiency. Moreover, the innovative integration of graphene with annular and L-shaped grooves to concentrate and amplify electromagnetic fields highlights a key advancement in absorber design.