非均匀分布的纳米银掺杂的聚合物分散液晶全息光栅等效电路建模  

Equivalent circuit modeling of non-uniformly distributed nano Ag doped Holographic polymer dispersed Liquid Crystal Grating

作　　者：刘悠嵘 郑继红[1] 桂坤[1] 王康妮[1] 庄松林[1] 

机构地区：[1]上海理工大学光电信息与计算机工程学院,上海200093

出　　处：《红外与毫米波学报》2017年第5期599-605,共7页Journal of Infrared and Millimeter Waves

基　　金：上海市重点学科项目第三期(S30502);国家重大科学仪器设备开发专项资助课题(2012YQ15008720)~~

摘　　要：聚合物分散液晶全息光栅具有电场可调的特点,材料中掺杂纳米银颗粒,能够有效降低光栅的驱动电压.由于聚合动力学的影响,会造成纳米银颗粒在光栅中的非均匀分布,即纳米银在聚合物和液晶区分布含量不均匀,表现出不同的电场调控特性.通过等效电路建模的方法研究驱动电压阈值与所施加交流电场的频率之间的关系.根据Maxwell-Wagner效应建立纳米银分别被液晶和聚合物包围的等效电路模型,具体研究在液晶条纹中,纳米银含量占总纳米银比例不同的条件下,纳米银掺杂的聚合物分散液晶全息光栅的介电弛豫时间和弛豫振荡的频率数值变化,进一步调节驱动电场频率,获得更低的驱动电压阈值.通过最优驱动电场频率范围来初步确定纳米银在光栅中的分布结构,并证明纳米银颗粒集中在液晶条纹,少量分布在聚合物条纹中.The diffraction efficiency of the holographic polymer-dispersed liquid crystal（ H-PDLC） grating can be adjusted by the applied electrical field. Doping Ag nanoparticles（ NPs） can effectively reduce the driving voltage of the grating. Due to the influence of polymerization kinetics,Ag NPs are distributed unevenly in the grating,namely,the distribution of Ag NPs in the polymer and LC area is not uniform and exhibit different electric field control characteristics. The relationship between the threshold driving voltage and the frequency of the applied field can be studied by equivalent circuit model. According to Wagner-Maxwell effect,in this paper,the equivalent circuit model of Ag NPs surrounded by LC and polymer,respectively,was established. Under the condition of different concentration of Ag NPs within the LC area,the relaxation time and relaxation frequency of Ag NPs doped HPDLC grating was studied. The lowdriving voltage can be further obtained by adjusting the frequency of applied electric field. The distribution of Ag NPs in the grating can be determined by the optimum driving electric field frequency range,and it is confirmed that the Ag NPs are concentrated in the LC strip and distributed in a small amount in the polymer stripes.

关 键 词：聚合物分散液晶全息光栅 弛豫振荡频率 阈值驱动电压 非均匀分布 

分 类 号：O438.1[机械工程—光学工程]