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为了实现温度与应变的双参数高精度传感测量,提出了一种CO_2激光刻写长周期光纤光栅(Long Period Fiber Grating,LPFG)与光纤马赫-增德尔(MZ)干涉型结构的光纤传感器,利用CO_2激光刻写制作LPFG并利用错位熔接法制备光纤MZ结构,将二者级联并实时监测温度及应变变化时的透射谱变化,研究了其传感原理并验证了其温度及应变传感特性。实验结果表明:该双参数光纤传感器的LPFG仅对温度敏感,MZ干涉结构对温度和应变都敏感;在温度范围35~70℃时,LPFG特征波长升温灵敏度38.57 pm/℃,降温灵敏度39.17 pm/℃;MZ干涉结构特征波长升温灵敏度38.57 pm/℃,降温灵敏度为37.50 pm/℃;当应变范围0~450με时,MZ干涉结构加载灵敏度4.01 pm/με,卸载灵敏度为4.24 pm/με。为温度和应变的实时测量提供了一种灵敏度高、线性度好的光纤传感器。
In order to measure the temperature and strain of two-parameter high-precision sensor, a fiber sensor based on CO_2 laser engraving Long Period Fiber Grating (LPFG) and optical fiber Mach-Zehnder interference (MZ) CO_2 laser engraving was used to fabricate LPFG. The MZ structure of optical fiber was fabricated by using the misalignment welding method. The transmission spectra were cascaded and the temperature and strain changes were monitored in real time. The sensing principle was studied and the temperature and strain sensing characteristics were verified. The experimental results show that the LPFG of this two-parameter optical fiber sensor is only sensitive to temperature and the MZ interference structure is sensitive to both temperature and strain. When the temperature is between 35 and 70 ℃, the LPFG characteristic wavelength temperature sensitivity is 38.57 pm / ℃ and the temperature sensitivity is 39.17 pm / ℃. The sensitivity of MZ interference structure is 38.57 pm / ℃ and the temperature sensitivity is 37.50 pm / ℃. When the strain range is 0-450 με, the loading sensitivity of MZ interference structure is 4.01 pm / με and the unloading sensitivity is 4.24 pm / με. For temperature and strain of real-time measurement provides a high sensitivity, good linearity optical fiber sensor.