叉指电极结构对液晶包层光波导有效折射率调制量影响的建模研究  

Modeling study of the effect of interdigital electrode structure on the effective refractive index modulation of liquid crystal clad optical waveguides

作　　者：赵慧茹 刁志辉[1,2] 穆全全 范维方[1,2,3] 陈澳 王宇晴 ZHAO Huiru;DIAO Zhihui;MU Quanquan;FAN Weifang;CHEN Ao;WANG Yuqing(State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,China;Key Laboratory of Optical System Advanced Manufacturing Technology,Chinese Academy of Sciences,Changchun 130033,China;University of Chinese Academy of Sciences,Beijing 101408,China)

机构地区：[1]中国科学院长春光学精密机械与物理研究所,应用光学国家重点实验室,吉林长春130033 [2]中国科学院光学系统先进制造技术重点实验室,吉林长春130033 [3]中国科学院大学,北京101408

出　　处：《液晶与显示》2024年第9期1163-1173,共11页Chinese Journal of Liquid Crystals and Displays

基　　金：吉林省全国重点实验室(学科类)重大专项(No.SKL202402022);长春市国家重点实验室(学科类)重大专项(No.23GZZ07);国家重点研发计划(No.2021YFB3600300)。

摘　　要：叉指电极基于单侧加电方式,有望通过简化波导层结构提升液晶包层光波导的光学性能。为此,本文建立了基于叉指电极的液晶包层光波导物理模型,并研究了该结构下波导模式有效折射率调制量的变化规律。首先,通过理论模拟明确了叉指电极所产生的电场分布特点;然后,分析了电场作用下液晶分子的排布状态及对波导模式有效折射率的作用规律,并定量化研究了液晶初始取向角度、Δn、Δε对波导模式有效折射率的影响;最后,对比了叉指电极与传统双侧电极结构下液晶光波导有效折射率调制量变化。结果表明,叉指电极会产生周期性电场分布,并导致液晶转动角度与光波导有效折射率分布呈现周期性;相比于平行取向(初始取向角为2°),垂直取向(初始取向角为88°)下所产生的有效折射率调制幅度更大,在40 V电压下,垂直取向是平行取向的10.1倍。更大的Δn和Δε有助于获得更大的光波导有效折射率调制量。与双侧电极对比,叉指电极能够在同等电压下实现更大的有效折射率调制量。The interdigital electrode is expected to improve the optical performance of the liquid crystal clad optical waveguide by simplifying the waveguide layer structure.Therefore,a physical model of the liquid crystal clad optical waveguide based on the interdigital electrode is established in this paper,and the changes of the effective refractive index modulation of the waveguide mode under this structure are studied.Firstly,the electric field distribution characteristics of the interdigital electrode are defined by theoretical simulation.Then,the configuration of liquid crystal molecules under electric field and its effect on the waveguide mode effective refractive index are analyzed,and the effects of the initial orientation angle,Δn,Δεon the waveguide mode effective refractive index are quantitatively studied.Finally,the effective refractive index modulation performance of the liquid crystal optical waveguide is compared between the interdigital electrode and the traditional two-sided electrode structure.The results show that the interdigital electrode produces periodic electric field distribution,and the rotation angle of the liquid crystal and the effective refractive index distribution of the optical waveguide are periodic.Compared with parallel orientation(initial orientation angle 2°),the effective refractive index modulation amplitude of vertical orientation(initial orientation angle 88°)is larger,and the effective refractive index modulation amplitude of vertical orientation is 10.1 times that of parallel orientation at 40 V voltage.LargerΔn andΔεare helpful to obtain larger effective refractive index modulation of optical waveguide.Compared with bilateral electrodes,interdigital electrodes can achieve a larger effective refractive index modulation at the same voltage.

关 键 词：叉指电极 液晶 光波导 

分 类 号：O753.2[理学—晶体学]