Graphene plasmons have attracted great interest for constructing high-performance functional metamaterial devices, among which graphene-based narrowband metamaterial absorbers are valuable in numerous applications. In this paper, a graphene-dielectric-metal hybrid structure is proposed to achieve dual-band excellent absorption and high-performance refractive index sensing. Numerical simulations show that the designed structure exhibits a high Q factor of 277.8 at 1.945 THz, which is higher than most previously-reported results. The sensitivity of the proposed structure can be up to 1.84 THz/RIU when the analyte thickness is 80 μm, and it exhibits promise for sensing thin-film biomolecule and thick biologic tissues. The electromagnetic field distributions show that the electromagnetic energy is highly confined in the structure at the higher order plasmon resonance, which plays an important role in achieving the excellent characteristics of the proposed structure. The tunability of the proposed structure is realized via changing the gate voltage applied to the graphene and the angles of the incident THz wave. In addition, we reveal that the proposed structure can be switched between single-band, dual-band, and 3-band absorption by tuning the incident angle under TM and TE polarization. Further results demonstrate that the proposed device possesses good thermal stability, polarization insensitivity, and outstanding fabrication tolerance. We believe that the proposed dual-band narrowband absorber can serve as a good example for other devices based on plasmons, such as selective sensors, modulators, and optical detectors.

石墨烯等离子体激元在构建高性能功能性超材料器件方面引起了极大的兴趣，其中基于石墨烯的窄带超材料吸收体在众多应用中具有重要价值。在本文中，提出了一种石墨烯-电介质-金属混合结构，以实现双波段优异的吸收和高性能的折射率传感。数值模拟表明，设计的结构在 1.945 THz 时表现出 277.8 的高 Q 因子，高于大多数先前报告的结果。当分析物厚度为 80 μm 时，所提出结构的灵敏度可高达 1.84 THz/RIU，并有望用于传感薄膜生物分子和厚生物组织。电磁场分布表明，电磁能在高阶等离子体共振下被高度限制在结构中，这在实现所提出结构的优异特性方面起着重要作用。所提出结构的可调性是通过改变施加到石墨烯上的栅极电压和入射太赫兹波的角度来实现的。此外，我们揭示了所提出的结构可以通过调整 TM 和 TE 偏振下的入射角在单波段、双波段和 3 波段吸收之间切换。进一步的结果表明，所提出的器件具有良好的热稳定性、偏振不敏感性和出色的制造公差。我们相信所提出的双频窄带吸收器可以作为其他基于等离子体激元的设备的一个很好的例子，