Sun Zhenci, Liang Chao, Chen Chen, Wang Xiayu, Zhou Enze, Bian Xiaomeng, Yang Yuanmu, You Rui, Zhao Xiaoguang, Zhao Jiahao, You Zheng
Department of Precision Instrument, Tsinghua University, Beijing 100084, China.
State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China.
Research (Wash D C). 2023 Dec 1;6:0274. doi: 10.34133/research.0274. eCollection 2023.
Terahertz (THz) wave manipulation, especially the beam deflection, plays an essential role in various applications, such as next-generation communication, space exploration, and high-resolution imaging. Current THz optical components and devices are hampered by their large bulk sizes and passive responses, limiting the development of high-performance, miniaturized THz microsystems. Tunable metasurfaces offer a powerful dynamic optical platform for controlling the propagation of electromagnetic waves. In this article, we presented a mechanically tunable metasurface (MTM), which can achieve terahertz beam deflection and vary the intensity of the anomalous reflected terahertz wave by changing the air gap between the metallic resonator (MR) array with phase discontinuities and Au ground plane. The absence of lossy spacer materials substantially enhances deflection efficiency. The device was fabricated by a combination of the surface and bulk-micromachining processes. The THz beam steering capability was characterized using terahertz time domain spectroscopy. When the air gap is 50 μm, the maximum deflection coefficient reaches 0.60 at 0.61 THz with a deflection angle of 44.5°, consistent with theoretical predictions. We further established an electrically tunable miniaturized THz device for dynamic beam steering by introducing a micro voice coil motor to control the air gap continuously. It is shown that our designed MTM demonstrates a high modulation depth of deflection coefficient ( 62.5%) in the target steered angle at the operating frequency. Our results showcase the potential of the proposed MTM as a platform for high-efficiency THz beam manipulation.
太赫兹（THz）波操控，尤其是光束偏转，在诸如下一代通信、太空探索和高分辨率成像等各种应用中发挥着至关重要的作用。当前的太赫兹光学元件和器件因其庞大的体积和被动响应而受到限制，这阻碍了高性能、小型化太赫兹微系统的发展。可调谐超表面为控制电磁波的传播提供了一个强大的动态光学平台。在本文中，我们展示了一种机械可调谐超表面（MTM），它可以通过改变具有相位不连续性的金属谐振器（MR）阵列与金接地平面之间的气隙来实现太赫兹光束偏转，并改变异常反射太赫兹波的强度。无损耗间隔材料的使用显著提高了偏转效率。该器件是通过表面微加工和体微加工工艺相结合制造的。利用太赫兹时域光谱对太赫兹光束转向能力进行了表征。当气隙为50μm时，在0.61THz频率下最大偏转系数达到0.60，偏转角约为44.5°，与理论预测一致。我们还通过引入微型音圈电机来连续控制气隙，建立了一种用于动态光束转向的电可调谐小型化太赫兹器件。结果表明，我们设计的MTM在工作频率下的目标转向角度处表现出高达约62.5%的偏转系数调制深度。我们的结果展示了所提出的MTM作为高效太赫兹光束操控平台的潜力。
