基于二色性染料及聚合物取向的液晶光开关的制备及其性能研究

Fabrication and performance of the liquid crystal optical switches based on dichroic dye and polymer orientation

为获得一种开关效应强、响应快且结构简单的光开关,对一种基于二色性染料及聚合物取向的液晶光开关进行研究。通过在垂直配向的液晶中加入二色性染料及聚合物,并在施加偏压的情况下照射紫外光使其发生聚合物取向效应,制得了一种具有电控偏光特性的液晶盒,进而将这种液晶盒按照偏光角度为0°/90°的方式组合为液晶光开关。对所制得液晶光开关的插入损耗、消光比和响应特性进行测试,结果表明,所制得的液晶光开关的插入损耗小于0.6dB、消光比超过13dB,具有较明显的开关效应,聚合物取向的方法则可以消除这种液晶光开关的迟滞现象,使其开关时间降低到20ms以内;通过聚合物取向过程所施加偏压的控制,二选一地,可以进一步减少其插入损耗或开关时间。

To obtain a kind of optical switch with strong switch effect, fast response and simple structure, the liquid crystal optical switch based on dichroic dye and polymer orientation is studied. By mixing dichroic dye and polymer into the vertically aligned liquid crystal, and irradiating it by ultraviolet light under a bias voltage to cause the polymer orientation effect, the liquid crystal cells with electrically controlled polarization characteristics were obtained,which were then assembled by the mode of 0°/90°of the polarization angle to realize the liquid crystal optical switch. The insertion loss, extinction ratio and response time of the liquid crystal optical switch were measured and compared. The measuring results show that the insertion loss of the liquid crystal optical switch can be less than 0, 6 dB,and the extinction ratio can be higher than 13 dB. And with the method of polymer orientation,the hysteresis of vertically aligned liquid crystal layer can be eliminated with the result of the response time lower than 20 ms. Beyond this, by controlling the bias voltage of the polymer orientation process, the insertion loss or the response time can be further reduced alternatively.