Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710069, People's Republic of China.
Nanotechnology. 2019 May 10;30(19):195705. doi: 10.1088/1361-6528/ab0329. Epub 2019 Jan 30.
Broadband terahertz (THz) impedance matching is important for both spectral resolution improvement and THz anti-radar technology. Herein, graphene-silicon hybrid structure has been proposed for active broadband THz wave impedance matching with optical tunability. The main transmission pulse measured in the time domain indicates a modulation depth as high as 92.7% totally from the graphene-silicon interface. The interface reflection from the graphene-silicon junction implies that an impedance matching condition can be actively achieved by optical doping. To reveal the mechanism, we propose a graphene-silicon heterojunction model, which gives a full consideration of both the THz conductivity of graphene and the loss in doped junction layer. The theory fits well with the experimental results. This work proves active THz wave manipulation by junction effect and paves the way for active anti-reflection coating for THz components.
宽带太赫兹（THz）阻抗匹配对于提高光谱分辨率和太赫兹反雷达技术都很重要。本文提出了一种基于石墨烯-硅混合结构的主动宽带太赫兹波阻抗匹配方法，具有光可调谐性。在时域中测量的主要传输脉冲表明，从石墨烯-硅界面的调制深度高达 92.7%。石墨烯-硅结的界面反射表明，通过光掺杂可以主动实现阻抗匹配条件。为了揭示这一机制，我们提出了一个石墨烯-硅异质结模型，该模型充分考虑了石墨烯的太赫兹电导率和掺杂结层的损耗。理论与实验结果吻合较好。这项工作通过结效应证明了太赫兹波的主动操控，为太赫兹元件的主动抗反射涂层铺平了道路。
