Inversely-designed terahertz metadevice with ultrafast modulation of double electromagnetically induced transparency windows  

作　　者：Siyang Hu Cheng Xiang’ai Weibao He Yuze Hu Mingyu Tong Zhongjie Xu 胡思扬;程湘爱;何韦宝;胡瑜泽;童明玉;许中杰(College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,China;Beijing Institute for Advanced Study,National University of Defense Technology,Beijing 100020,China)

机构地区：[1]College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,China [2]Beijing Institute for Advanced Study,National University of Defense Technology,Beijing 100020,China

出　　处：《Chinese Optics Letters》2022年第11期100-104,共5页中国光学快报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 62075240);the National Key Research and Development Program of China (No. 2020YFB2205800)。

摘　　要：Terahertz metasurfaces have great applications for efficient terahertz modulation, but there are still problems in designing terahertz metadevices in terms of complexity and inefficiency. Herein, we demonstrate an inversely-designed terahertz metasurface with double electromagnetically induced transparency(EIT)-like windows by incorporating a particle swarm optimization(PSO) algorithm with the finite-difference time-domain method. We prepared and tested the metadevices, and the experimental terahertz signals are close to the designed results. By hybridizing amorphous germanium film with the inversely-designed metasurface, two EIT-like windows, including transmission and slow-light effect, exhibit ultrafast modulation behavior in 25 ps excited by a femtosecond laser. The modulation depths of transmission in two transparency windows are 74% and 65%, respectively. The numerical simulations also illustrate the ultrafast dynamic process and modulation mechanism, which match well with the experiment results. Our work thus offers opportunities for designing other objective functions of the terahertz metadevice.

关 键 词：terahertz metasurfaces inverse design double electromagnetically induced transparency 

分 类 号：O441.4[理学—电磁学]