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<p>This paper proposes a graphene-based absorbing metasurface operating in the terahertz (THz) range, featuring switchable and tunable frequency bands. By applying a bias voltage to adjust the Fermi level of graphene, two distinct operating states can be achieved. When <i>E</i><sub><i>f</i></sub> = 1.1&#xa0;eV, the absorption exceeds 90% within 2.8–8.7 THz; when <i>E</i><sub><i>f</i></sub> = 0.08&#xa0;eV, strong absorption persists across 0.1–4.1 THz. In both frequency bands, the metasurface exhibits good impedance matching with free space. Furthermore, analysis using the phase cancellation metric confirms that the asymmetric configuration of the dielectric substrate is a key factor for broadband impedance matching. Based on the Drude model of graphene and the dispersion relation of surface waves, the observed blue shift in absorption with varying Fermi levels is explained.The metasurface maintains high absorption for both TE and TM waves under wide incident angles at <i>E</i><sub><i>f</i></sub> = 1.1&#xa0;eV and <i>E</i><sub><i>f</i></sub> = 0.08&#xa0;eV, achieving efficient absorption even at an incident angle of 60°. It also shows polarization insensitivity. The absorption mechanisms under the two operating states are analyzed using the equivalent circuit model and multiple interference theory, respectively, and the results are consistent with the simulations.The electric and magnetic field distributions further clarify the mechanism behind the efficient broadband absorption. In terms of fabrication and experimental design, reasonable improvements have been made based on existing strategies. Finally, a comparison with previous works demonstrates that the proposed metasurface achieves an integrated capability of dual-band switchability, tunability, and ultra-broadband absorption, showing great potential for applications in THz electromagnetic shielding, communication, and related fields.</p>

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Dynamically tunable dual-band graphene metasurface for terahertz absorption

  • 期刊论文

  • 发表日期：

    2025年12月9日

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  • Xunyu Guo,
  • Zhaoyang Shen,
  • Jun Zhang

摘要

This paper proposes a graphene-based absorbing metasurface operating in the terahertz (THz) range, featuring switchable and tunable frequency bands. By applying a bias voltage to adjust the Fermi level of graphene, two distinct operating states can be achieved. When Ef = 1.1 eV, the absorption exceeds 90% within 2.8–8.7 THz; when Ef = 0.08 eV, strong absorption persists across 0.1–4.1 THz. In both frequency bands, the metasurface exhibits good impedance matching with free space. Furthermore, analysis using the phase cancellation metric confirms that the asymmetric configuration of the dielectric substrate is a key factor for broadband impedance matching. Based on the Drude model of graphene and the dispersion relation of surface waves, the observed blue shift in absorption with varying Fermi levels is explained.The metasurface maintains high absorption for both TE and TM waves under wide incident angles at Ef = 1.1 eV and Ef = 0.08 eV, achieving efficient absorption even at an incident angle of 60°. It also shows polarization insensitivity. The absorption mechanisms under the two operating states are analyzed using the equivalent circuit model and multiple interference theory, respectively, and the results are consistent with the simulations.The electric and magnetic field distributions further clarify the mechanism behind the efficient broadband absorption. In terms of fabrication and experimental design, reasonable improvements have been made based on existing strategies. Finally, a comparison with previous works demonstrates that the proposed metasurface achieves an integrated capability of dual-band switchability, tunability, and ultra-broadband absorption, showing great potential for applications in THz electromagnetic shielding, communication, and related fields.