基于单一倾斜光纤光栅的温度应变同时测量

Simultaneous measurement of temperature and strain based on single tilted fiber Bragg grating

利用光纤光栅分析软件OptiGrating对倾斜光纤光栅温度与应变传感进行系统的理论仿真,研究发现,温度、应变的变化都可以引起倾斜光纤光栅的纤芯模和包层模谐振峰的漂移,而且温度和应变对纤芯模与包层模的影响是各不相同的。利用倾斜光纤光栅这一特性,提出了一种基于单一倾斜光纤光栅的温度与应变同时测量的传感系统,并通过实验进行了验证。在实验中,光电探测器可以将倾斜光纤光栅的波长的漂移转换成电压的变化,由此得到了倾斜光纤光栅只受温度变化时,随着温度的变化,示波器测到其纤芯模与包层模的电压(峰—峰值)的变化呈线性变化,其斜率分别为0.063 39mV/℃和0.001 89mV/℃;其只受应变变化时,随着应变的变化,示波器测到其纤芯模与包层模的电压(峰—峰值)的变化也呈线性变化,其斜率分别为0.009 59mV/με,0.001 96mV/με。研究结果将对倾斜光纤光栅的传感应用具有一定的指导意义。

OptiGrating, a type of software for fiber Bragg grating （FBG） analysis, was used for systematic theoretical simulation of temperature and strain sensingof tilted fiber Bragg grating （TFBG）. The results show that the change of both temperature and strain can lead to the drift of harmonic peak of core mode and cladding mode of TFBG,while temperature and strain have different impacts on core mode and clad- ding mode. In accordance with such a feature of TFBG, a sensing system based on single TFBG for measuring temperature and strain simultaneously is proposed and then verified by experiments. In the experiment, the photo deteetor is able to transform the wavelength drift of the TFBG to voltage varia- tions. Thus it can be concluded that the core mode voltage and dad mode voltage （peak-peak value） both show linear variation with the eurve slopes of 0.06339 mV/℃ and 0.00189 mV/℃ ,respectively,as on- ly the temperature changes. The core mode voltage and clad mode voltage （peak-peak value） also show linear variation with the curve slopes of 0. 009 59 mV/με and 0. 001 96 mV/με,respectively,as only the strain changes. Our findings can be used to guide the sensing application of TFBG.