Pura Jose Luis, Deop-Ruano Juan R, Abujetas Diego R, Giannini Vincenzo, Manjavacas Alejandro, Sánchez-Gil José A
Instituto de Estructura de la Materia (IEM-CSIC), Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid, Spain.
GdS-Optronlab, Física de la Materia Condensada, Universidad de Valladolid, Paseo de Belén 19, 47011 Valladolid, Spain.
Nanophotonics. 2023 Dec 4;12(24):4453-4460. doi: 10.1515/nanoph-2023-0463. eCollection 2023 Dec.
Bound states in the continuum (BICs) in metasurfaces have lately attracted a great deal of attention stemming from their inherent (formally) divergent factors, which lead to an enhancement of light-matter interaction in two-dimensional geometries. However, the development of plausible means to actively manipulate them remains a major challenge. The use of graphene layers has recently been suggested, employed either as a substrate or a coating that modifies the dielectric environment of the metasurface. Here, instead, we propose to exploit graphene disk dimers supporting in-plane plasmons directly as active meta-atoms in a square array. We prove analytically that both the emergence of a BIC and its factor can be tuned in an active manner by applying a different external potential to each of the disks in the dimer, thus being formally equivalent to engineering the disk diameters in a passive, geometrically-dependent manner. Moreover, we propose an approach to mitigate the effect of the inherent losses of graphene plasmons based on exploiting the collective behavior of the array, which is achieved by adjusting the lattice parameter so that the wavelength of the BIC mode lies closer to the Rayleigh anomaly.
超表面中的连续域束缚态（BICs）近来因其固有的（形式上的）发散因子而备受关注，这些因子导致二维几何结构中光与物质相互作用的增强。然而，开发合理的方法来主动操控它们仍然是一项重大挑战。最近有人提出使用石墨烯层，将其用作改变超表面介电环境的基底或涂层。在此，我们提出直接利用支持面内等离子体激元的石墨烯盘二聚体作为方形阵列中的有源超原子。我们通过分析证明，通过对二聚体中的每个盘施加不同的外部电势，可以以主动方式调节BIC的出现及其因子，因此在形式上等同于以被动的、几何相关的方式设计盘直径。此外，我们提出了一种基于利用阵列集体行为来减轻石墨烯等离子体激元固有损耗影响的方法，这是通过调整晶格参数来实现的，使得BIC模式的波长更接近瑞利异常。
