保偏光纤侧视成像定轴技术仿真研究

Simulation research on side-looking imaging alignment technique of PMF

通过建立保偏光纤侧视成像定轴系统仿真模型,分析了POL(Polarization observation by the Lens-effective tracing)定轴算法的精度,结果表明熊猫型保偏光纤应力区位置出现3.2μm的偏差时,该算法的定轴误差为1°左右。产生误差的主要原因是:由于应力区位置不严格对称,光纤后焦平面上所得的侧视成像光强分布中心光强值不再是最能准确反映偏振轴方位角位置的特征点。基于此,文中对POL定轴算法做了相应改进,以光强分布中实际最大光强值代替中心光强值作为特征点,然后利用特征点构建出标准曲线,进而采用间接相关的方法完成定轴。理论计算结果表明,改进后的定轴算法可以实现更高的理论定轴精度。

The simulation model of side-looking imaging alignment system of polarization-maintaining fiber（ PMF） was established. Based on this model,the accuracy of polarization observation by the lens-effective tracing（ POL） technique was analyzed. The results show that the error of the algorithm is about 1° when stress regions position of Panda PMF has a deviation of 3. 2 μm. As stress region position is not asymmetric absolutely,center light intensity value of the intensity distribution on fiber focal plane has not been the characteristic points which can represent the azimuth angle position of polarization axis accurately. Thus,the algorithm error is aroused. The algorithm of POL technique is improved. Firstly,actual maximum light intensity value instead of center light intensity value is used as characteristic points. These characteristic points are then used for constructing a standard curve. Finally,azimuth angle of polarization axis is determined with indirect correlation method. The theoretical calculation results show that the new algorithm has higher precision.