利用自制研磨机侧边研磨了应力双折射型偏振保持布拉格光纤光栅(PMFBG),并对研磨过程中的透射光谱与反射光谱进行了监测。研磨过程中造成的功率损耗小于0.6 dB,PMFBG的两个布拉格波长均发生了漂移,且两者的间距有变小的趋势。通过曲线拟合得到了两个偏振态的有效折射率随研磨深度的变化规律,并分析得出:光纤芯子中心的应力双折射随研磨过程先逐渐减小,后缓慢变化,在研磨深度d=47μm时达到最小值,减小至未研磨时的0.6倍。利用此特性,经过侧边研磨的应力双折射型光纤光栅可用于对双折射精度要求较高的器件的研制中。
The polarization maintaining fiber Bragg grating(PMFBG) with stress-induced high-birefringence was side-polished by a self-made side-polishing machine.The reflection and transmission spectrum was monitored during the polishing process.The power loss induced by side-polishing was smaller than 0.6 dB.The two Bragg wavelengths of the PMFBG had a trend of decreasing on both shift and their distance.The rules of the two polarization modes′ effective indexes with the polishing depth are obtained through the curves fitting.It is summarized that the stress-induced birefringence at the core center of the fiber decreases firstly and then changes slowly during polishing process.When the polishing depth reaches to 47 μm,the stress-induced birefringence decreases to 60 percent of the original.Based on the characteristics,the side-polished stress-induced high-birefringence fiber can be used to realize many fiber devices which must have accurate birefringence.