负性液晶电致图案化及其衍射特性  

Electro-patterning and diffraction properties in negative liquid crystals

作　　者：尚小虎 姜皓译 宋振鹏 刘娇[1] 李炳祥 SHANG Xiaohu;JIANG Haoyi;SONG Zhenpeng;LIU Jiao;LI Bingxiang(College of Electronic and Optical Engineering and College of Flexible Electronics(Future Technology),Nanjing University of Posts and Telecommunications,Nanjing 210023,China)

机构地区：[1]南京邮电大学电子与光学工程学院、柔性电子(未来技术)学院,江苏南京210023

出　　处：《液晶与显示》2024年第3期312-321,共10页Chinese Journal of Liquid Crystals and Displays

基　　金：国家重点研发计划(No.2022YFA1405000);国家自然科学基金(No.62375141);江苏省自然科学基金(No.BK20212004)。

摘　　要：液晶中电对流图案形成是一种奇特而又有趣的现象,同时也是光衍射研究中的一个重要问题。本文旨在探索负介电各向异性的向列相液晶中图案的形成以及相关的衍射特性。实验观察到4种不同的电对流图案,分别是软方形图案、斜条纹、静脉状图案和不规则图案。探究了不同温度下产生图案所需要的阈值电压。研究了电场对图案的周期性以及相对指向矢倾斜角的影响,并对图案相应的衍射特性进行了分析。实验结果表明,通过调节电场和温度可以改变电对流图案。产生图案所需要的阈值电压随着温度的升高而减小,随着频率的升高而增大。软方形图案的周期随着频率的升高先减小后增大,而斜条纹的周期随频率的升高而减小。当f=25~45Hz时,斜条纹相对于初始指向呈现约44°的偏转。这种可控的电对流图案为实现基于向列相液晶的可调谐光学衍射器件提供了一种可行方案。Pattern formation of electroconvection in liquid crystals is a peculiar and intriguing phenomenon,and it also poses an important problem in the study of optical diffraction.This work aims to explore pattern formation and related diffraction characteristics in dielectrically negative anisotropic nematic liquid crystals.Four different electroconvection patterns are observed experimentally,namely,soft square,oblique rolls,skewed varicose,and irregular patterns.The threshold voltages required for pattern generation at different temperatures are investigated.The effect of electric field on the periodicity of patterns and the inclination angle of the relative director are studied,and the corresponding diffraction characteristics of the patterns are analyzed.The experimental results show that electroconvection patterns can be altered by adjusting the electric field and temperature.The threshold voltage required for pattern generation decreases with the increase of temperature and increases with the growth of frequency.The periodicity of soft square patterns initially decreases and then increases with the increase of frequency,while the periodicity of oblique rolls decreases with the increase of frequency.When f=25~45 Hz,the oblique rolls exhibit an approximately 44°deviation from the initial director.This controllable electroconvection pattern provides a feasible solution for the realization of tunable optical diffraction devices based on nematic liquid crystals.

关 键 词：液晶 图案形成 衍射 电场 电对流 

分 类 号：O753.2[理学—晶体学]