Recently, based on the selective excitation of the guided mode, researchers realized quasi-bound states in the continuum (quasi-BICs) in all-dielectric compound grating waveguide structures. In this paper, we introduce a graphene layer into an all-dielectric compound grating waveguide layer supporting quasi-BIC to achieve near-infrared perfect absorption of graphene. The underlying physical mechanism of perfect absorption can be clearly explained by the critical coupling theory derived from temporal coupled-mode theory in a single-mode, one-port system. By changing the Fermi level and the layer number of the graphene, the absorption rate of the system can be flexibly tuned. In addition, by changing the geometric parameter of the compound grating waveguide structure, the radiation coupling rate of the quasi-BIC can also be flexibly tuned. Therefore, the critical coupling condition can be maintained in a broad range of the Fermi level and the layer number of the graphene. The full width at half maximum of the near-infrared perfect absorption peak can be flexibly tuned from 5.7 to 187.1 nm. This bandwidth-tunable perfect absorber would possess potential applications in the design of 2D material-based optical sensors, electrical switchers, and solar thermophotovoltaic devices.

中文翻译：

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在连续谱中支持准束缚态的复合光栅波导结构中石墨烯的带宽可调近红外完美吸收

最近，基于导模的选择性激发，研究人员在全介电复合光栅波导结构中实现了连续体（quasi-BICs）中的准束缚态。在本文中，我们将石墨烯层引入支持准 BIC 的全电介质复合光栅波导层中，以实现石墨烯的近红外完美吸收。完美吸收的潜在物理机制可以通过从单模单端口系统中的时间耦合模式理论导出的临界耦合理论清楚地解释。通过改变费米能级和石墨烯的层数，可以灵活地调整系统的吸收率。此外，通过改变复合光栅波导结构的几何参数，还可以灵活调节准BIC的辐射耦合率。所以，临界耦合条件可以保持在费米能级和石墨烯层数的广泛范围内。近红外完美吸收峰的半峰全宽可以在 5.7 到 187.1 nm 之间灵活调整。这种带宽可调的完美吸收器将在基于二维材料的光学传感器、电气开关和太阳能热光伏器件的设计中具有潜在的应用。