液晶Lieb晶格衍射偏振特性分析  

Analysis of polarization characteristics of liquid crystal Lieb lattice diffraction

作　　者：曹雅娴 戴海涛[1] 刘迎[1] 高美妮 付宜铠 刘昌龙[1] 郝希晨 王雨涵 陈贞达 王若同 姚不已 冯守中 CAO Yaxian;DAI Haitao;LIU Ying;GAO Meini;FU Yikai;LIU Changlong;HAO Xichen;WANG Yuhan;CHEN Zhenda;WANG Ruotong;YAO Buyi;FENG Shouzhong(School of Sciences,Tianjin University,Tianjin 300355,China;Anhui Zhongyi New Material Technology Co.Ltd.,Chuzhou 239599,China)

机构地区：[1]天津大学理学院,天津300355 [2]安徽中益新材料科技有限公司,安徽滁州239599

出　　处：《液晶与显示》2024年第5期620-628,共9页Chinese Journal of Liquid Crystals and Displays

基　　金：国家自然科学基金(No.62375200,No.12274319);政府间科技例会交流项目。

摘　　要：Lieb晶格是被研究较多具有平带特性的完整晶格结构之一。本文基于液晶光控取向技术制备了Lieb晶格,通过改变曝光的偏振方向,构建了晶格位点内液晶为90°扭曲(TN)取向、图案外为均匀(PA)取向的液晶Lieb晶格结构。测量了在外加电场作用下,不同入射方案的液晶Lieb晶格的衍射特性。通过偏振测试仪测试了在不同外加电场作用下的多个衍射级次的偏振特性。实验结果表明,施加电压时衍射图样中衍射光斑的级次增多;随电压升高到约2.5 VPP,液晶Lieb晶格结构的衍射效果变差,除了零阶衍射光斑,各衍射级次衍射光斑强度达到最弱;增加电压至4 VPP,各级次衍射光斑强度逐渐增强,衍射图案逐渐清晰。在改变电压的过程中,各种入射情况的不同阶次衍射光的偏振态也在逐渐改变,一阶衍射光在1~3 VPP之间有+45°线偏振光、-45°线偏振光、右旋圆偏振光、左旋圆偏振光等特殊偏振态出现。本文提出的液晶Lieb晶格具有易调控、易制备等特性,通过调控施加在液晶上的电压,可以实现衍射级次偏振态的动态调控,为光场调控提供了新的方式。Lieb lattice is one of the most studied complete lattice structures with flat band properties.In this paper,the Lieb lattice is prepared based on the liquid crystal light orientation technology.By changing the polarization direction of exposure,the LC Lieb lattice structure is constructed with the liquid crystal 90°twisted(TN)orientation inside the lattice site and uniform(PA)orientation outside the pattern.The diffraction characteristics of liquid crystal Lieb lattice with different incidence schemes are measured under different applied electric field.The polarization characteristics of multiple diffraction orders under different applied electric fields are measured by polarization tester.The experiments show that the order of diffraction spots increases when voltage is added.As the voltage increases to about 2.5 VPP,the diffraction effect of liquid crystal Lieb lattice structure becomes worse,and the intensity of diffraction spots is the weakest except for zero-order diffraction spots.When the voltage increases to 4 VPP,the intensity of the diffraction spots is gradually enhanced,and the diffraction pattern is gradually clear.In the process of changing the voltage,the polarization state of the diffracted light of different orders in various incident cases also gradually changes,and the first-order diffracted light has special polarization states such as+45°linear polarized light,-45°linear polarized light,right-handed circularly polarized light,and left-handed circularly polarized light between 1 VPP and 3 VPP.The liquid crystal Lieb lattice proposed in this paper has the characteristics of easy regulation and preparation.By regulating the voltage applied on the liquid crystal,the dynamic regulation of the diffraction order polarization state can be realized,which provides a new way for the light field regulation.

关 键 词：液晶Lieb晶格 光控取向 外加电场 偏振 衍射图样 

分 类 号：O753.2[理学—晶体学]