为了实现蔗糖溶液浓度与温度的同步精确测量, 采用组合式光纤光栅, 通过线性折射率分区, 构成相应的系数矩阵。首先, 基于模式耦合理论, 采用光纤布拉格光栅(FBG)和长周期光纤光栅(LPBG)形成组合式光纤光栅, 实现了双参数测量的光学传感器。此组合式光纤光栅结构中, FBG响应温度测量, LPFG同时响应蔗糖溶液浓度和温度测量。然后, 在两个线性折射率范围, 即133~142和142~144中, 校正温度和蔗糖溶液浓度的相关系数。最后, 构成两个敏感系数矩阵, 来讨论蔗糖溶液浓度和温度同时测量的方法。实验结果表明: 蔗糖溶液浓度测量灵敏度达到-2135 pm/RIU, 温度测量灵敏度达到1179 pm/K。因此, 组合式光纤光栅传感器作为光化学传感器具有高灵敏度的特性。

In order to accurately measure temperature and concentration of sugar solution at the same time, we presented a hybrid fiber grating sensor. Firstly, based on mode coupling theory, hybrid fiber gratings were formed using fiber Bragg grating and long-period fiber grating, which could realize dual-parameters measurement. In this hybrid fiber grating, FBG response to temperature measurement, while LPFG response to simulataneous measurement of sugar solution concentration and temperature. Then, in two linear refractive index ranges, that is, from 133 to 142 and from 142 to 144, we calibrated correlation coefficient of temperature and sugar concentration. Finally, two sensitivity coefficient matrixes were constituted to discuss the method of measuring temperature and sugar solution concentration simultaneously. Experimental results indicate that the measuring sensitivity of temperature reaches 1179 pm/K, and sugar solution concentration reaches –2135 pm/RIU. Therefore, the modular fiber grating sensor has high sensitivity property as the photochemical sensor.