High‐Performance Tunable Broadband Graphene Metasurface Terahertz Absorber Based on Surface Plasmon Resonance

ABSTRACT To overcome the limitations of narrow bandwidth, structural complexity, and limited tunability in existing graphene‐based terahertz absorbers, structural complexity, or inconvenient tunability in existing graphene‐based terahertz absorbers, this paper proposes a tunable broadband terahertz absorber based on a graphene proportional metasurface. Here, “proportional” refers to the fixed ratio between the graphene pattern feature size () and the unit cell period (), that is, , as well as the consistent size ratios among different resonant regions. The design employs a classic three‐layer structure, consisting of a gold reflective layer, a silicon dioxide dielectric layer, and a graphene resonant absorption layer. Through systematic optimization, the absorber achieves a high‐efficiency absorption bandwidth exceeding 90% across a range of 3.003 THz, with a peak absorption rate of 98.8% at 2.61 THz and an average absorption rate of 94.6% over the entire bandwidth. It also exhibits excellent impedance matching characteristics and angular adaptability. Research indicates that the broadband absorption property of the device originates from the electric field coupling effect between different resonant units. This coupling effect causes multiple absorption peaks to overlap, thereby broadening the bandwidth. Furthermore, by applying an external voltage to adjust the Fermi level of graphene, the absorption bandwidth can be continuously tuned. The device offers flexible dynamic control capabilities and demonstrates good tolerance to the incident angle of electromagnetic waves. This study provides a feasible approach for designing structurally simple and tunable high‐efficiency terahertz absorbers. The proposed design holds potential application value in fields such as terahertz detection, communication, and stealth technology.