Zeng Tian-Yi, Liu Gui-Dong, Wang Ling-Ling, Lin Qi
Opt Express. 2021 Nov 22;29(24):40177-40186. doi: 10.1364/OE.446072.
In this paper, we propose a graphene-dielectric metasurface to enhance the light-matter interactions in graphene. The dielectric metasurface consists of periodically arranged silicon split rings placed on the silica substrate, which supports a symmetry-protected bound state in the continuum (BIC). When perturbation is introduced into the system to break symmetry, the BIC will transform into the quasi-BIC with high quality (Q)-factor. As the graphene layer is integrated with the dielectric metasurface, the absorption of graphene can be enhanced by the quasi-BIC resonance and a bandwidth-tunable absorber can be achieved by optimizing the Fermi energy of graphene and the asymmetry parameter of the metasurface to satisfy the critical coupling condition. By varying the Fermi energy of graphene, the quasi-BIC resonances can be effectively modulated and the max transmission intensity difference is up to 81% and a smaller asymmetry parameter will lead to better modulation performance. Our results may provide theoretical support for the design of absorber and modulator based on the quasi-BIC.
在本文中，我们提出了一种石墨烯 - 电介质超表面，以增强石墨烯中的光与物质相互作用。该电介质超表面由周期性排列在二氧化硅衬底上的硅裂环组成，其支持连续统中的对称保护束缚态（BIC）。当向系统引入微扰以打破对称性时，BIC将转变为具有高品质（Q）因子的准BIC。由于石墨烯层与电介质超表面集成在一起，石墨烯的吸收可以通过准BIC共振得到增强，并且通过优化石墨烯的费米能和超表面的不对称参数以满足临界耦合条件，可以实现带宽可调谐吸收器。通过改变石墨烯的费米能，可以有效地调制准BIC共振，最大透射强度差高达81%，并且较小的不对称参数将导致更好的调制性能。我们的结果可能为准BIC基吸收器和调制器的设计提供理论支持。
