用于向列相液晶取向测量的侧边抛磨光纤传感特性研究

Side-Polished Fiber Sensing for Measurement of Nematic Liquid Crystal Orientation

向列相液晶（NLC）的取向变化对外界环境敏感，已被作为生物传感的敏感中介材料。研究了侧边抛磨光纤（SPF）用于NLC取向变化测量的传感特性，探索利用SPF测量液晶取向变化的可行性与适用范围。将液晶折射率的理论公式与SPF传输光功率实验数据结合，得到了经验理论关系。实验中设计用机械旋转法改变SPF抛磨面附近NLC的取向。实验结果表明，NLC的取向变化导致SPF传输光功率的变化。以液晶指向矢方位角为表征的NLC的取向变化从0°增大至90°，SPF传输光功率随之增大28．10dB；在0°～30°范围内，SPF传输光功率与NLC的取向变化具有线性关系，光纤传输光功率对取向角度变化的响应平均约为0．359dB／（°）。研究表明SPF可以用于NLC的取向变化的测量并且获得了适用范围，这为基于液晶取向变化的SPF生物传感器的研究提供了参考。

The orientation change of nematic liquid crystal （NLC） can be used in biosensor. The sensing characteristics of sidempolished fiber （SPF） for measurement of NLC orientation are investigated. The relationship between the theoretical formula of liquid crystal refractive index and the optical transmission power in SPF is derived by empirical approach. The mechanical rotating method is designed to change the orientation of NLC on the polished surface. Experimental results show that the orientation variation of liquid crystal can indeed be used to monitor the output optical power transmitted through the SPF. With mechanical rotation method, when the rotation angle increases from 0° to 90°, the output optical power increases by 28.10 dB. With in the angle range from 0° to 30°, the response is almost linear. The average response slope is about 0. 359 dB/（°）, which indicates relatively high sensitivity. Experiments indicate that SPF can be used to measure the orientation variation of NLC, and the variation range is also obtained. The work provides a reference for a new fiber optical biosensor based on the SPF and NLC.