在液晶盒的上下基板表面分别旋涂平行和垂直取向剂形成HAN液晶盒,将具有光敏特性的预聚物与向列相液晶按一定比例混合,注入液晶盒,进行全息曝光,形成布拉格光栅。实验结果表明,光栅的驱动电压从9.2V/um降到5.7V/um,同时衍射效率也从83%上升到98.4%。分析认为,上下基板取向剂对液晶分子进行了取向,在提高相分离程度的同时也改善了富液晶区域的分子排列,从而实现了光栅电光特性的改善。
Photosensitive monomers were mixed together with nematic liquid crystal with certain mass ratio. Then the mixture was injected into a Hybrid alignment cell, the substrates of which were coated with parallel alignment layer and vertical alignment layer, respectively. The phase separation between monomers and liquid crystals was induced by laser beam interference bright patterns and form Bragg grating. Experimental results indicated that the diffraction efficiency of grating increases from 83 % to 98.4% and the driving voltage was lowered to 5.7 V/um. These analytical results showed that the alignment layer influents the orientation of LC droplet directors, so it improves the electro-optical properties of gratings as well as the alignment of LC molecule in the LC zone.