Universal polarization terahertz phase controllers using randomly aligned liquid crystal cells with graphene electrodes
Universal polarization terahertz phase controllers using randomly aligned liquid crystal cells with graphene electrodes
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DOI：
10.1364/ol.40.001544
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发表时间：
2015-04-01
期刊：
影响因子：
3.6
通讯作者：
Ono, Hiroshi
中科院分区：
文献类型：
--
作者：
Sasaki, Tomoyuki;Noda, Kohei;Ono, Hiroshi
我们提出了一个通用的偏振太赫兹（THz）相位控制器使用随机排列的液晶（LC）细胞与石墨烯电极。LC单元使用双折射LC和涂覆有单层石墨烯作为透明电极的两个石英基板来制造。在没有任何配向处理的情况下制备单元中的LC，并且将其随机配向。LC层中随机畴的尺寸和向错线的宽度为几十微米。当通过石墨烯层向LC施加交流电压时，这些纹理消失。利用太赫兹时域光谱技术，我们研究了液晶盒的复透射率。该液晶盒在THz频率范围内具有高度的透明性，并且透射率随施加电压的变化很小。这表明，散射损失起源于随机排列的LC分子是小的太赫兹波。我们还证明了太赫兹相移可以通过施加电压来控制。用液晶的寻常折射率和非寻常折射率解释了相移的幅度。这些具有石墨烯电极的LC单元由于随机排列而可用于实现通用偏振THz相位控制器。(C)2015美国光学学会
We present a universal polarization terahertz (THz) phase controller using a randomly aligned liquid crystal (LC) cell with graphene electrodes. The LC cell was fabricated using a nematic LC and two quartz substrates that were coated with a monolayer of graphene as the transparent electrode. The LC in the cell was prepared without any alignment treatments and was randomly aligned. The size of the random domains and the width of the disclination lines in the LC layer were several tens of microns. These textures disappeared when an alternating voltage was applied to the LC through the graphene layers. Using a THz time domain spectroscopic technique, we investigated the complex transmittance of the LC cell. The LC cell was highly transparent in the THz frequency range, and there was little change in the transmittance with the applied voltage. This indicated that the scattering loss originating in the randomly aligned LC molecules was small for the THz waves. We also demonstrated that the THz phase shift could be controlled by the applied voltage. The amplitude of the phase shift was explained by the ordinary and extraordinary refractive indices of the LC. These LC cells with graphene electrodes can be used to realize universal polarization THz phase controllers because of the random alignment. (C) 2015 Optical Society of America