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

The impact of nematic liquid crystal(NLC) cell with surface orientation in three different assembly on the performance of all-optical switch has been experimentally researched by using liquid crystal 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, respectively. 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.