表面垂直取向对HPDLC光栅特性的影响  

Surface vertical alignment effect on performance of holographic polymer dispersed liquid crystal gratings

作　　者：李文萃[1] 舒新建[1] 杨燚[1] 黄文彬[2] 

机构地区：[1]国网河南省电力公司信息通信公司,河南郑州450052 [2]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

出　　处：《应用光学》2014年第6期987-990,共4页Journal of Applied Optics

基　　金：国家自然科学基金(60736042;11174274;11174279;61205021;11204299)

摘　　要：为了提高聚合物/液晶(HPDLC)光栅的衍射效率并改善光栅的表面形貌,研究了表面垂直取向处理对HPDLC光栅的影响。首先,研究了表面垂直处理对液晶分子的取向作用,发现垂直取向层对液晶的锚定作用随着盒厚的增加而逐渐减弱,取向层的作用范围大概在3μm^5μm之间;其次,对相分离程度进行了实验表征,结果表明,随着液晶盒厚度的增加,相分离开始的时间越来越快,并且分离程度也越来越彻底。最后,讨论了表面垂直取向对HPDLC光栅衍射效率的影响,随着盒厚的增加,相分离出来的液晶微滴形成连续的区域,光栅的衍射效率逐渐升高,当盒厚增加到一定程度,其衍射效率和无取向处理的光栅接近。当盒厚过大时,垂直取向处理对HPDLC光栅散射损失并没有太大的改善,只有当盒厚适中(12μm)时,光栅的衍射效率最高,散射损失最小。In order to get the holographic polymer dispersed liquid crystal (HPDLC ) grating with high diffraction efficiency and perfect morphology ,the effect of surface vertical alignment on the properties of HPDLC grating was investigated .Firstly ,the effect of the vertical surface treatment on the orientation of liquid crystal molecules was studied .It is found that the vertical anchor effect of liquid crystal decreases with the increase of cell gap and the orientation depth is about 3 μm ~ 5 μm .Secondary ,the characterization experiment of separation was done .And results show that as the cell gap increases ,the surface effect on the bulk LC droplets reduces due to the longer distance .For the thinner cell ,almost all the LC droplets are confined on the inner surfaces of the substrates which cannot flow and coalesce with the neighboring droplets , so the phase separate is not good .However ,if the cell is too thick ,the effect of vertical align‐ment on the LC droplets in the middle of the cell is very small and the bulk droplets are less or‐dered so that the morphology is similar to those of conventional (without vertical alignment) HPDLC cells .Experimental results indicate that only in the condition of certain surface vertical alignment strength(cell gap is 12 μm ) ,the HPDLC with high diffraction efficiency and low scattering loss can be realized .

关 键 词：表面垂直取向 HPDLC 衍射效率 散射损失 

分 类 号：O631.24[理学—高分子化学]