Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes
Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes
复制标题
用多孔石墨烯电极驱动的宽带可调谐液晶太赫兹波片
DOI：
10.1038/lsa.2015.26
复制
发表时间：
2015-02-01
影响因子：
19.4
通讯作者：
Lu, Yan-Qing
中科院分区：
文献类型：
--
作者：
Wang, Lei;Lin, Xiao-Wen;Lu, Yan-Qing
用于太赫兹成像、传感和高速通信的多功能器件，特别是可调谐器件，需求量很大。基于液晶的组件是光学范围内的完美候选者;然而，它们在太赫兹波段遇到了重大挑战，特别是缺乏高度透明的电极和厚电池引起的缺点。在这里，提出了一种克服所有这些挑战的策略：采用少层多孔石墨烯作为电极，其透射率超过98%。亚波长金属线栅被用作集成的高效电极和偏振器。通过非接触式光对准技术在两个脆弱电极上实现了高双折射液晶的均匀对准。由此获得可调谐太赫兹波片。直接展示了其极化演化过程。此外，通过堆叠两个电池来实现在整个测试范围内可电控制的四分之一波片。所提出的解决方案可以为各种液晶太赫兹设备的开发铺平一条简单而光明的道路。
Versatile devices, especially tunable ones, for terahertz imaging, sensing and high-speed communication, are in high demand. Liquid crystal based components are perfect candidates in the optical range; however, they encounter significant challenges in the terahertz band, particularly the lack of highly transparent electrodes and the drawbacks induced by a thick cell. Here, a strategy to overcome all these challenges is proposed: Few-layer porous graphene is employed as an electrode with a transmittance of more than 98%. A subwavelength metal wire grid is utilized as an integrated high-efficiency electrode and polarizer. The homogeneous alignment of a high-birefringence liquid crystal is implemented on both frail electrodes via a non-contact photo-alignment technique. A tunable terahertz waveplate is thus obtained. Its polarization evolution is directly demonstrated. Furthermore, quarter-wave plates that are electrically controllable over the entire testing range are achieved by stacking two cells. The proposed solution may pave a simple and bright road toward the development of various liquid crystal terahertz apparatuses.