基于差分群时延的磁场传感中光纤布拉格光栅结构影响的性能分析

Effect of Grating Structure on Magnetic Field Sensor Exploiting Differential Group Delay in Fiber Bragg Gratings

对基于差分群时延的磁场测量方法中光纤布拉格光栅(FBG)结构的影响进行了分析。利用耦合模理论和传输矩阵法仿真,分析了均匀FBG的长度和折射率调制系数对传感系统测量范围和灵敏度的影响。同时改变FBG制作结构,研究了啁啾光栅、相移光栅和切趾光栅的差分群时延性能。并对各种光栅结构的差分群时延峰值大小进行了理论和实验比较。对均匀光栅和相移光栅的实验比较测量表明,采用相移光栅结构可以明显提高传感测量系统的灵敏度,实验数据和理论吻合较好。

The characteristics of grating structure in magnetic field measurements based on differential group delay of fiber Bragg gratings（FBG） are analyzed.Theoretical simulations are realized using the coupled-mode theory and transfer matrix method.The effects of grating parameters（physical length,index modulation） of uniform FBG on measurement range and sensitivity are analyzed.The impacts of chirped,phase-shifted and apodized gratings on the wavelength dependency of differential group delay are also monitored.The experimental measurements are conducted on FBG inscribed by means of the phase mask technique.The experiments demonstrate that the phase-shifted gratings can obviously improve the sensitivity of sensor system which match well with the simulations.