He Xunjun, Sun Chenguang, Wang Yue, Lu Guangjun, Jiang Jiuxing, Yang Yuqiang, Gao Yachen
Key Laboratory of Engineering Dielectric and Applications (Ministry of Education), Harbin University of Science and Technology, Harbin 150080, China.
College of Electronic Engineering, Guangxi Normal University, Guilin 541004, China.
Nanomaterials (Basel). 2021 Sep 17;11(9):2420. doi: 10.3390/nano11092420.
Currently, metasurfaces (MSs) integrating with different active materials have been widely explored to actively manipulate the resonance intensity of multi-band electromagnetic induced transparency (EIT) windows. Unfortunately, these hybrid MSs can only realize the global control of multi-EIT windows rather than selective control. Here, a graphene-functionalized complementary terahertz MS, composed of a dipole slot and two graphene-integrated quadrupole slots with different sizes, is proposed to execute selective and active control of dual-band electromagnetic induced reflection (EIR) windows. In this structure, dual-band EIR windows arise from the destructive interference caused by the near field coupling between the bright dipole slot and dark quadrupole slot. By embedding graphene ribbons beneath two quadrupole slots, the resonance intensity of two windows can be selectively and actively modulated by adjusting Fermi energy of the corresponding graphene ribbons via electrostatic doping. The theoretical model and field distributions demonstrate that the active tuning behavior can be ascribed to the change in the damper factor of the corresponding dark mode. In addition, the active control of the group delay is further investigated to develop compact slow light devices. Therefore, the selective and active control scheme introduced here can offer new opportunities and platforms for designing multifunctional terahertz devices.
目前，已广泛探索了与不同活性材料集成的超表面（MSs），以主动操纵多波段电磁诱导透明（EIT）窗口的共振强度。不幸的是，这些混合超表面只能实现对多EIT窗口的全局控制，而不是选择性控制。在此，提出了一种由偶极狭缝和两个不同尺寸的集成石墨烯的四极狭缝组成的石墨烯功能化互补太赫兹超表面，以对双波段电磁诱导反射（EIR）窗口进行选择性和主动控制。在这种结构中，双波段EIR窗口源于亮偶极狭缝和暗四极狭缝之间近场耦合引起的相消干涉。通过在两个四极狭缝下方嵌入石墨烯带，可通过静电掺杂调节相应石墨烯带的费米能量，从而选择性地、主动地调制两个窗口的共振强度。理论模型和场分布表明，主动调谐行为可归因于相应暗模式阻尼因子的变化。此外，还进一步研究了群延迟的主动控制，以开发紧凑的慢光器件。因此，本文介绍的选择性和主动控制方案可为设计多功能太赫兹器件提供新的机遇和平台。
