基于石墨烯超材料的可调谐电磁诱导透明

Tunable electromagnetically induced transparency based on graphene metamaterial

提出了一种基于石墨烯超材料的可调谐电磁诱导透明(EIT)结构,该结构是由长条-半圆环形状的石墨烯层和介质基底组成。通过频域有限差分法研究了该结构的特性,研究结果表明,由于石墨烯条和石墨烯半圆环之间发生相互作用,产生较弱的杂化,从而可以观察到EIT透明窗口。更重要的是,通过控制门电压,改变石墨烯的费米能级,可以在较宽的频率范围内实现透明窗口的动态调谐。通过调节石墨烯的费米能级,在透射峰附近群延迟接近0.4ps。同时还研究了石墨烯条和半圆环间的距离、圆环的半径、方位角等几何参数对EIT效应的影响,这些因素的改变对EIT效应产生了不同的影响。本文设计的超材料结构可应用于调制器和慢光器件等,对光开关、光存储等新型器件的设计有重要的指导意义。

A tunable electromagnetically induced transparency （EIT） structure based on graphene meta- material is proposed in this paper. The structure is made up of the striphalf ring graphene layers on the substrate. The characteristics of the structure are studied by the frequency domain method finite differ- ence. The simulation confirms that an EIT like transparency window can be observed due to frequency detuning and the weak hybridization of the strip and the half ring graphene layers. More importantly, the peak frequency of the transmission window can be dynamically controlled over a broad frequency range by varying the Fermi energy levels of the graphene layer through controlling the electrostatic gating. Correspondingly,by adjusting the Fermi energy of the graphene, a group delay of 0.4 ps is obtained in the vicinity of the transparency peaks. The effect of the distance between the strip and the ring, the radi- us of the ring and the azimuth angle on the E1T effect are also studied. The changes of these factors have different impacts on the EIT. The metamaterial structure designed in this paper can be applied in modu- lators and slow light devices, and has important guiding significance for the design of new devices, such as optical switching and optical storage.