相移光栅磁场传感方案交叉敏感分析

Analysis of the Cross Sensitivity of Magnetic Field Sensor with Phase-Shifted Grating

通过相移光栅的偏振相关损耗(PDL)进行磁场测量是一种较为新颖的磁场测量方法,可用于对脉冲交变强磁场的测量。交叉敏感问题是光纤光栅传感中的关键问题。忽略光栅固有双折射,利用传输矩阵法对磁场传感原理进行了推导与仿真,理论分析了温度、轴向应力和压力等对相移光栅透射窗口的影响,并对相应的PDL峰值变化进行了数值仿真。理论和实验表明,透射窗口峰值的波长随温度和轴向应力呈线性变化,PDL谱线发生横向平移,磁场传感系统不受影响。压力的变化改变了光栅的折射率分布,产生应力双折射,PDL谱线发生不规则变化,对磁场测量结果产生严重影响。

The measurement of magnetic field through the polarization dependent loss（PDL） of phase-shifted grating is a more novel approach.It can be used to measure the pulse alternating strong magnetic field.The key issue of fiber grating sensor is the cross-sensitive.Ignoring the inherent birefringence of gratings,the principle of magnetic field sensing is derived and simulated by transfer matrix method.The influence of the temperature,axial stress and pressure on the transmission window of phase-shifted grating is theoretical analyzed,and the corresponding changes of the PDL peak value are simulated.The results show that the wavelength of transmission window peak value changes linearly with temperature and axial stress,PDL spectrum horizontal lines shift,and the result of magnetic field measurement will not be affected.The refractive index changed with pressure causes the irregular change of PDL spectrum,having a serious impact on the magnetic field measurement.