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挠曲电效应对液晶微波相位调制的影响

Influence of flexoelectric effect on the microwave phase modulation of liquid crystal

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摘要

液晶微波调制器件的相位调制取决于液晶分子指向矢的分布。液晶指向矢的分布不仅会受基板表面处液晶分子预倾角和锚定能等因素的影响, 液晶材料的挠曲电特性同样会影响液晶指向矢分布。基于液晶弹性理论和差分迭代方法, 研究了挠曲电效应对平行排列向列相(PAN)液晶微波相位调制的影响, 理论推导得到弱锚定PAN液晶盒的平衡态方程, 数值模拟给出了不同的预倾角、锚定能和液晶材料的挠曲电特性条件下单位长度微波相移(MPSL)随电压的变化。结果表明MPSL随锚定能系数的减小而增大, A0=Ad=5×10-5J/m2时, 挠曲电效应e11+e33=5×10-11C/m对MPSL最大可调范围为20°, 0°预倾角对MPSL最大可调范围为17°, MPSL差值最大增加均为9°; 预倾角为3°时, MPSL可调范围随挠曲电系数的增大而增大, 相对于忽略挠曲电效应情形, 强锚定A0=Ad=10-3J/m2条件下MPSL始终减小, 弱锚定A0=Ad=5×10-5J/m2条件下MPSL先减小后增大然后再减小, MPSL差值最大增加为9°。此项研究对液晶微波调制器件设计有一定的指导意义。

Abstract

The phase modulation of the liquid crystal microwave modulator depends on the distribution of the liquid crystal molecular director. The distribution of liquid crystal director is not only affected by these factors such as the pretilt angle of the liquid crystal molecules and the anchoring energy on the surface of the substrate. The flexoelectric effect of the liquid crystal material also affects the liquid crystal director distribution. Based on the elastic theory of liquid crystal and the finite-difference iterative method, the influence of flexoelectric effect on the microwave phase modulation of parallel aligned nematic (PAN) liquid crystal is studied. We get the equilibrium equations of the weak anchoring PAN cell. The numerical simulation shows the variation of microwave phase shift per unit length (MPSL) with voltage under different pretilt angles, anchoring energies and flexoelectric coefficients of the liquid crystal material. The results show that the MPSL increases with the decrease of anchoring energy. The maximum adjustable range of MPSL is 20° under A0=Ad=5×10-5J/m2 when e11+e33=5×10-11C/m. Due to the flexoelectric effect, the maximum adjustable range of MPSL is 17° when the pretilt angle is 0°, and the maximum difference increase of MPSL is 9°. When the pretilt angle is 3°, the adjustable range of MPSL increases with the increase of e11+e33, and the MPSL always decreases under A0=Ad=10-3J/m2, while the MPSL first decreases, then increases, and eventually decreases under A0=Ad=5×10-5J/m2. The maximum difference increase of MPSL is 9° relative to ignoring the flexoelectric effect. This study has some guiding significance for the design of liquid crystal microwave modulator.

Newport宣传-MKS新实验室计划
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中图分类号:O753.2

DOI:10.3788/yjyxs20183301.0023

所属栏目:材料与器件

基金项目:国家自然科学基金(No.11374087;No.11504080); 河北省自然科学基金(No.A2014202123; No.A2017202004)、河北省教育厅项目(No.QN2014130); 河北省高校重点学科资助课题

收稿日期:2017-07-14

修改稿日期:2017-08-15

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作者单位    点击查看

李振杰:河北工业大学 理学院, 天津 300401
袁 瑞:河北工业大学 理学院, 天津 300401
孙婷婷:河北工业大学 理学院, 天津 300401
朱吉亮:河北工业大学 理学院, 天津 300401
叶文江:河北工业大学 理学院, 天津 300401

联系人作者:李振杰(lizhenjieruning@163.com)

备注:李振杰(1993-), 男, 山东菏泽人, 硕士研究生, 主要从事液晶与液晶器件物理方面的研究。

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引用该论文

LI Zhen-jie,YUAN Rui,SUN Ting-ting,ZHU Ji-liang,YE Wen-jiang. Influence of flexoelectric effect on the microwave phase modulation of liquid crystal[J]. Chinese Journal of Liquid Crystals and Displays, 2018, 33(1): 23-29

李振杰,袁 瑞,孙婷婷,朱吉亮,叶文江. 挠曲电效应对液晶微波相位调制的影响[J]. 液晶与显示, 2018, 33(1): 23-29

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