CO_2激光刻写长周期光纤光栅与光纤MZ结构的双参数传感特性

Dual-parameter sensing characterisitics of long period fiber grating cascaded with fiber MZ structure fabricated by CO_2 laser

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 achieve the temperature and strain of the two-parameter high-precision sensor measurements, a dual-parameter measurement of long period fiber grating（LPFG） fabricated by CO2 laser cascaded with fiber Mach-Zehnder （MZ） interference structure was proposed. The LPFG was fabricated using the CO2 laser and the fiber MZ structure was fabricated using dislocation welding method. The sensing principle was derived and the transmission spectrum of the cascaded structure was monitored for temperature and strain measurements. The experimental results show that the LPFG is sensitive only to the temperature while the MZ structure is sensitive to both temperature and strain, when the temperature varied from 35℃ to 70℃, the LPFG sensitivities for warming and cooling are 38.57 pm/℃ and 39.17 pm/℃, respectively, while the MZ structure sensitivities are 38.57 pm/℃ and 37.50 pm/℃, respectively. When the strain varied from 0 με to 450 με, the MZ structure sensitivities for loading and unloading are 4.01 pm/με and 4.24 pm/με, respectively. A sensor with high sensitivity and good linearity for real-time and dynamic range measurements of dual-parameter was developed.