液晶盒表面取向排列对光敏混合液晶全光开关性能的影响

Impact of liquid crystal cell with surface orientation in different assembly on performance of all-optical switch by using photosensitive liquid crystal mixtures

利用混合液晶,实验研究了间隔厚度为125μm的向列相液晶(NLC)盒的无定向排列、平行排列和扭曲排列3种表面取向排列方式对全光开关性能影响。全光开关采用光敏混合液晶(15%BMAB,85%NLCs)注入NLC盒制作而成。实验结果表明,无定向排列NLC盒和扭曲排列NLC盒都可实现全光开关效应;扭曲排列NLC盒的表面取向作用不仅可以提高全光开关的稳定性和重复性,还可以提高全光开关的调制深度和响应速度;相对无定向排列NLC盒,扭曲排列NLC盒制作的全光开关的稳定性和上升响应速度分别提高了1倍,调制深度提高了4.8 dB。实验验证了NLC盒的表面取向作用可提高全光开关性能,对提高结合光敏液晶和光纤制作光控全光纤器件的性能有重要指导意义。

The impact of nematic liquid crystal（NLC） cell with surface orientation in three different as- sembly on the performance of all-optical switch has been experimentally researched by using liquid crys- tal mixtures. Here the thickness of NLC cell is equal to the diameter of standard single mode fiber, 125 μm,and these three kinds of assembly are non-oriented, parallel-aligned and twisted alignment,respec- tively. The all-optical switch is made of these NLC cells filled with photosensitive liquid crystal mixtures （15~ BMAB, 85~ NLCs）. The experimental results show that both non-oriented and twisted NLC cells can obtain all-optical switch effect. The surface orientation of the twisted NLC cell can improve not only the stability and repeatability of all-optical switch, but also its modulation depth and response rate. Compared with non-oriented NLC cell,both the stability and the rise response rate of all-optical switch based on the twisted NLC cell are measured to be enhanced doubly and the modulation depth is improved by 4.8 dB as well. This research has experimentally confirmed that NLC cell with surface orientation can improve the performance of all-optical switch, which points out the way for improving the performance of the all-optical controlled all-fiber devices by using photosensitive LCs and fiber.