基于光纤光栅差分群时延的磁感应强度测量新方法

New Measurement for Electromagnetic with the Differential Group Delay of Fiber Grating

提出了一种利用光纤光栅中法拉第效应和测量差分群时延(DGD)的直接测量磁感应强度的新方法,给出了理论分析和实验结果。当有外加磁感应强度时,光纤光栅中的法拉第效应致使两个圆偏振光的传播常数改变,从而导致光纤光栅的群时延发生改变。仿真结果表明,外加磁感应强度与DGD峰值在一定的测量范围内存在线性关系。分析了光纤光栅对测量性能的影响。实验结果表明,测量磁感应强度的灵敏度为1.3 ps/T,利用现有精度为10^(-5)ps的光矢量分析仪得到最小可测磁感应强度为10^(-5)T,实验与理论吻合较好,证明了该方案的可行性。

A new magnetic field measurement based on the Faraday effect and the measurement of differential group delay （DGD） in fiber grating was proposed. When the magnetic field was applied, the propagation constants of the two circularly polarized light in fiber grating were changed by the Faraday effect, then insulting in the change of the DGD of fiber grating. The simulations showed the linear relationship between the peak value of DGD and magnetic field in certain range. The influences of fiber grating on the measurement performance were analyzed. The measurement sensitivity was 1.3 ps/T and the smallest magnetic induction is 10.5 T using the optical vector analyzer with precision of 10^- 5 ps. The experimental results agree well with the theoretical analysis.