液晶调控下的亚波长金光栅反射相位  

Subwavelength gold gratings refection phase modulated by liquid crystals

作　　者：李韵九 韦穗[1] 郝学锋 葛博群 沈川 屈磊[1] LI Yunjiu;WEI Sui;HAO Xuefeng;GE Boqun;SHEN Chuan;QU Lei(Key Laboratory of Intelligent Computing&Signal Processing,Ministry of Education,Anhui University,Hefei 230601,China)

机构地区：[1]安徽大学计算智能与信号处理教育部重点实验室,安徽合肥230061

出　　处：《液晶与显示》2024年第11期1445-1453,共9页Chinese Journal of Liquid Crystals and Displays

基　　金：国家自然科学基金(No.62271005);安徽省高校自然科学基金(No.2022AH050089,No.KJ2020ZD02)。

摘　　要：空间光调制器(Spatial Light Modulator,SLM)是实现光场调控的关键器件。本文研究了一种将亚波长金光栅嵌入硅基液晶(Liquid Crystal on Silicon,LCoS)构成的SLM(G-LCoS)器件模型的反射相位特性,该器件模型以ITO透明导电层和液晶构成G-LCoS中亚波长金光栅的非对称边界。首先运用散射矩阵原理给出了亚波长金光栅反射相位的计算表达式,其次给出了下表面液晶的有效折射率计算公式。在此基础上,利用TechWiz 3D软件模拟加电情况下金光栅下表面液晶指向矢的变化,给出金光栅下表面液晶有效折射率的变化值。将得到的有效折射率数据导入到FDTD Solutions软件,对该器件结构开展了相关的仿真实验和结果分析。综合考虑了上表面的ITO色散情况、金光栅高度变化以及不同电压下液晶有效折射率值,实现了可见光范围内多波长的近2π相位调制。本文研究的器件也为AR/VR显示系统以及全息视频显示的优化提供了一种新思路。Spatial light modulator(SLM)is a key device to realize light field modulation.In this paper,the reflection phase characteristics of a SLM(G-LCoS)device model consisting of a subwavelength gold grating embedded in a liquid crystal on silicon(LCoS)are investigated,which is composed of an ITO transparent conductive layer and liquid crystals to form the asymmetric boundary of a subwavelength gold grating in G-LCoS.Firstly,the expression for the reflection phase of the subwavelength gold grating is given by applying the scattering matrix principle.Secondly,the formula for the effective refractive index of the liquid crystal on the lower surface is given.On this basis,TechWiz 3D software is used to simulate the change of the pointing vector of the liquid crystal on the lower surface of the gold grating when applying an additional voltage,and the change value of the effective refractive index of the liquid crystal on the lower surface of the gold grating is given.The obtained effective refractive index data are imported into FDTD Solutions software,and relevant simulation experiments and results are analyzed for the device structure.The ITO dispersion of the upper surface,the change of the height of the gold grating and the value of the effective refractive index of the liquid crystal at different voltages are taken into account to realize the near 2πphase modulation of multiple wavelengths in the visible range.The device studied in this paper also provides a new idea for the optimization of AR/VR display system and holographic video display.

关 键 词：亚波长金属光栅 散射矩阵 液晶有效折射率 相位调制 空间光调制器 

分 类 号：O436[机械工程—光学工程]