基于聚合物分散液晶的二维六角晶格变间距光栅的研制

Development of Two-Dimensional Hexagonal Lattice Variable Line-Space Grating Based on Polymer-Dispersed Liquid Crystal

利用柱面波与平面波干涉形成一种二维(2D)全息聚合物分散液晶(H-PDLC)变间距光栅。为了使聚合物与液晶分离得更加彻底,采用曝光强度为16mW/cm2、波长为532nm的激光进行实验,并且两次曝光时间分别为2s和60s,通过将样品二次曝光和旋转60°形成2D六角晶格H-PDLC变间距光栅,分别研究了光栅的理论周期变化范围、衍射特性、电控特性以及影响光栅周期变化的参数分析。结果表明:在半径为6 mm的圆形范围内,光栅的周期变化区间为1.804~2.281μm,与理论计算所得结果基本一致。在没有加载电压的情况下,一级衍射效率达18.3%,当加载电压达到90V时,零级衍射效率由15.6%增加至73%。该光栅具有变周期和电控特性,在衍射光学领域具有潜在的应用价值,可用于染料掺杂2D H-PDLC光栅的可调谐多波长有机激光器的研究。

A two-dimensional（2 D）holographic polymer-dispersed liquid crystal（H-PDLC）variable line-space grating is fabricated by interference between cylindrical wave and plane wave.In order to separate polymer from liquid crystal more evidently,we use a 532 nm laser with exposure intensity of 16 mW/cm2 in experiment,and two exposure time is 2 sand 60 s,respectively.We use double exposure and rotate the sample 60°to form 2 Dhexagonal lattice H-PDLC variable line-space grating.The theoretical periodic variation rang of grating,diffraction properties,electronic control characteristics and analysis of parameters affecting the periodic change of grating are studied,respectively.The results show that,in the circular range with a radius of 6 mm,the periodic variation range of the grating is 1.804-2.281μm,which is basically consistent with the theoretical calculation.The first-order diffraction efficiency is 18.3% without external voltage,and the zero-order diffraction efficiency increases from 15.6%to 73%with an applied voltage of 90 V.Due to variable period and electronic control characteristics,this grating has potential application in diffraction optics,such as the research of tunable multi-wavelength organic laser for dyedoped 2 D H-PDLC grating.