偏振对于光纤光栅传感器工作性能影响的研究

Influence of Polarization on Grating Performance

基于布拉格衍射理论的光纤光栅传感器应用于温度、浓度、应力等参量高精度测量,通常要求高精度的波长分辨率。当入射光波前有偏振态存在时,将会对光栅系统的波前测量结果产生误差。在保偏光纤中,偏振对于光栅的影响尤为严重。当光栅周期与光栅矢量排布方向发生改变时,它与带有偏振信息波前作用后的衍射波前也会发生变化,而且在不同的衍射级上影响会有所差异,在精密波前检测方法中往往忽略了这种差异,从而对于光学波前的高精度检测存在误差。本文基于有限时域差分算法,计算在不同偏振态光束入射以及不同光栅周期与光栅矢量排布时偏振对于检测精度的影响。最终得到在不同偏振态光束入射时,光栅采用不同期与矢量排布,对于衍射波前的误差反应。

Fiber grating sensor based on Bragg diffraction theory requires high precision wavelength resolution.When there is polarization state in the front of incident light,there will be errors in the wavefront measurement of grating system.In polarization maintaining fiber,the influence of polarization on grating is particularly serious.When the grating period and the direction of grating vector arrangement are changed,the diffraction wavefront with polarization information will also change,and the influence will be different at different diffraction levels.However,this difference is often ignored in the precision wavefront detection methods,so there are errors in the high-precision detection of optical wavefront.Based on the finite difference time domain(FDTD)algorithm,the influence of polarization on the detection accuracy is calculated for different polarized light beams,different grating period and grating vector arrangement.Finally,we get the error response of diffractive wavefront when the grating is arranged in different periods and vectors with different polarization states.