基于双芯光纤级联布拉格光纤光栅的温度与应力解耦双测量传感系统

Decoupling Dual Measurement Sensor System of Temperature and Strain Based on Twin-Core Fiber Cascaded with Fiber Bragg Grating

提出了一种基于耦合型双芯光纤级联布拉格光纤光栅的温度与应力双参数解耦测量的全光纤型传感系统。实验制备了一系列不同长度的双芯光纤滤波器,并测量分析了其自由光谱范围与双芯光纤长度的关系,结果与理论基本一致。实验发现双芯光纤及布拉格光栅对施加应力与环境温度的变化具有不同的光谱响应。利用光谱分析仪实时监测双芯光纤透射光谱波谷处波长及光纤光栅透射谱的波长漂移量,方便地实现了温度与应力的解耦双测量。多次测试发现该传感器对应力与温度响应特性具有良好的重复性,波长误差低于实验所用光谱仪分辨率。对于0.01 nm波长分辨率的光谱仪,提出的全光纤型传感器可以分别实现4.3048με及0.4562℃的应力与温度传感测量分辨率。

A novel all-fiber sensing configuration for decoupling measurement of temperature and strain based on the twin core fiber（TCF） with an in-line embedded fiber Bragg grating（FBG） is proposed.A series of TCF filters with different lengths are fabricated experimentally, and the relationship between the free spectral range（FSR） and the fiber length of these filters is measured and analyzed, which are in agreement with the theory. It is found during the experiment that the TCF and FBG have different spectral responses for the changing strain and temperature. Optical spectrum analyzer（OSA） is used to monitor the wavelength at the bottom of the TCF transmitted spectrum and the wavelength drift of the fiber grating transmitted spectrum.The sensor tested has favorable repeatability for the responses of strain and temperature, and has a lower wavelength error compared with the spectrometer used in experiment. Withing a spectrometer having a wavelength distinguishability of 0.01 nm, the proposed all-fiber sensor can reach a distinguishability of4.3048 με for stress and 0.4562 °C for temperature.