基于液晶光波导的电控偏振旋转器  

Electrically controlled polarization rotator based on liquid crystal optical waveguide

作　　者：查正桃 张谦述 ZHA Zheng-tao;ZHANG Qian-shu(School of Physics and Astronomy,China West Normal University,Nanchong 637009,China;School of Electronic Information Engineering,China West Normal University,Nanchong 637009,China)

机构地区：[1]西华师范大学物理与天文学院,四川南充637009 [2]西华师范大学电子信息工程学院,四川南充637009

出　　处：《中国光学》2022年第3期552-561,共10页Chinese Optics

基　　金：四川省科技厅科研基金(No.2014JY0024);南充市科技局科研基金(No.19YFZJ0090);西华师范大学英才科研基金(No.17YC056)。

摘　　要：为了更准确地分析基于液晶光波导的电控偏振旋转器的偏振转换长度和偏振转换效率,研究了向列相液晶场致重新取向的渐变特性。首先,根据液晶磁场耦合方程组得出的本征值方程构建偏振转换长度与外加电压的对应关系。然后通过对电场传输方程进行横向有限差分离散得到了交替方向隐式束传播法迭代方程组的显式表达,用于求解液晶光波导中的传播场,进而计算偏振转换效率。最后,通过仿真实验求解了本征模式以及传播场,进而分析液晶指向矢的渐变特性对偏振转换长度和偏振转换效率的影响。结果表明,液晶指向矢的渐变对偏振转换长度的影响可以忽略,但其得出的最大偏振转换效率相较于液晶重新取向均匀的求解结果低大约20%。这一结果将为基于液晶光波导的电控偏振旋转器的实际开发提供理论参考。In this study,the gradient characteristic of field-induced reorientation of nematic liquid crystal was investigated to accurately analyze the Polarization Conversion Length(PCL)and Polarization Conversion Efficiency(PCE)of an electronically controlled polarization rotator based on a liquid crystal optical waveguide.Firstly,according to the eigenvalue equation obtained from the liquid crystal magnetic field coupling equations,the corresponding relationship between PCL and the applied voltage was constructed.Then,the explicit expression of the iterative equations of the Alternating Direction Implicit Beam Propagation Method(ADI-BPM)was obtained by transverse finite-difference discretization of the electric field transmission equation,which was used to solve the propagation field in the liquid crystal optical waveguide and calculate the PCE.Finally,the eigenmode and propagation field were solved through a simulation experiment,and then the effects of the gradient characteristics of the liquid crystal director on PCL and PCE were analyzed.The results show that the effect of the gradient of the liquid crystal director on the PCL can be ignored,but the maximum PCE is about 20%lower than that of the uniform reorientation of the liquid crystal.This result will provide a certain theoretical reference for the practical development of an electronically controlled polarization rotator based on a liquid crystal optical waveguide.

关 键 词：液晶 光波导 偏振旋转器 电调谐 

分 类 号：TN252[电子电信—物理电子学] O753.2[理学—晶体学]