液晶填充F-P腔高精度温度传感器的研究

Study on High Precision Temperature Sensor in Fabry-Perot Cavity Filled With Liquid Crystal

利用光纤光栅反射波长和液晶折射率的温度敏感特性,在两光纤光栅构成的F-P腔中填充向列相液晶,形成液晶填充的光纤光栅F-P腔温度传感器。用耦合模理论得到了这种传感器的反射率和反射谱线带宽与温度的关系式,数值计算了反射光谱随温度的变化。结果表明当温度升高时,传感器的反射率和反射谱的形状将发生变化,反射谱向长波长方向发生整体缓慢平移,反射谱带宽增大,谐振谱线数增加。越接近液晶相变点上述变化越明显。这种温度传感器克服了传统光纤光栅传感器中温度应力的交叉敏感影响,可用于温度的高精度监测。

The temperature sensor of Fabry-Perot（F-P） cavity filled with liquid crystals are proposed by filling fiber grating F-P cavity with nematic liquid crystal（NLC）. By making use of the temperature sensitivity of LC refractive index and reflection wavelength of fiber grating, the formula of reflectivity and reflection spectra bandwidth with temperature were obtained by applying the couple mode theory, and the changes of the relection spectra with temperature were numerically calculated. The results show that when temperature increases, the reflectivity and reflection spectra shape would change, the whole reflection spectra would shift slowly towards the long wavelength, and the reflection spectra bandwidth and humorous spectra number would increase. Closer to the liquid crystal clear point, more obvious the changes would be. In such temperature sensors, cross-sensitivity eoused by temperature and strain in traditional FBG sensors were overcome and they could be used in high precision temperature monitoring.