In this paper, a broadband and tunable terahertz absorber based on a graphene metasurface in a sandwiched structure is introduced. A single-layered graphene patterned with hollow-out squares is applied in this design, which is continuously connected to provide convenience for electrical tuning and fabrication. Plasmonic coupling and hybridization inside the graphene pattern can significantly enhance the absorption bandwidth. Moreover, polarization-insensitive and omnidirectional performances are also guaranteed by the symmetrical design. Full wave simulations demonstrate that the absorber exhibits over 90% absorbance within 1.14∼3.31 THz with a fractional bandwidth up to 97.5%. The device reveals tunable absorbance from 14% to almost 100% by manipulating the graphene chemical potential from 0 to 0.9 eV. When the incident angle sweeps up to 55°, the absorbance remains more than 90% from 1.77 to 3.42 THz for TE polarization, while over 90% absorbance maintains around 3.3 THz for TM polarization. These superior abilities guarantee the applicability of the presented absorber in THz cloaking, tunable sensor and photovoltaic devices.

中文翻译：

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基于单层石墨烯超表面的可调宽带太赫兹吸收器

本文介绍了一种基于石墨烯夹层结构的可调谐宽带太赫兹吸收器。在该设计中应用了带有空心正方形图案的单层石墨烯，该石墨烯被连续连接以为电调谐和制造提供方便。石墨烯图案内部的等离子体耦合和杂交可以显着提高吸收带宽。此外，对称设计还保证了偏振不敏感和全向性能。全波模拟表明，该吸收剂在1.14〜3.31 THz范围内表现出超过90％的吸收率，其分数带宽高达97.5％。该器件通过将石墨烯的化学势控制在0至0.9 eV之间，可显示14％至100％的可调吸收率。当入射角扫描到55°时，对于TE偏振，从1.77到3.42 THz，吸光度保持超过90％，而对于TM偏振，超过90％的吸光度保持在3.3 THz左右。这些卓越的能力确保了本发明的吸收器在太赫兹隐身，可调谐传感器和光伏设备中的适用性。