保偏光纤制备及其参数测试原理

Principle of preparation and parameters test of polarization-maintaining fiber

为了研制工作波长为1310 nm的保偏光纤,采用改进的化学气相沉积工艺制备了保偏光纤预制捧和应力棒,经加工、拼接、清洗、拉丝工艺后,得到几何尺寸精确的高质量保偏光纤;同时搭建了高效测试系统,采用折射近场法、远场扫描法、视频灰度技术(传输近场),分别测量了预制棒的折射率分布和几何尺寸,保偏光纤模场直径、数值孔径、几何尺寸等关键参数。结果表明,此标准化测试系统操作流程简单、结果精确;模场直径为6.26μm,数值孔径为0.23,包涂直径80μm/135μm/165μm(精度±0.7μm);终检测试合格的光纤成品随机抽样16.25%,高低温老化实验后拍长、串音变化小。所研制的保偏光纤性能稳定,几何尺寸精确、结构均匀、损耗低,具有优良保偏性能,已广泛应用于实际生产中。

In order to develop a polarization-maintaining fiber with a working wavelength of 1310 nm,the prepare preform and stress rod of polarization-maintaining(PM)fiber were prepared by a modified chemical vapor deposition process.The high-quality PM fiber with precise geometric size was produced after processing,splicing,cleaning,and drawing.At the same time,an efficient test system was set up to measure the refractive index and geometry of preform,mode-field diameter(MFD),and numerical aperture(NA),and geometry of PM fiber by technologies such as the refractive near-field method,far-field scanning and,video gray scale technology(transmission near field).The results show that the standardized test system has simple operation and accurate results,and MFD is 6.26μm,NA is 0.23,and cladding and coating diameter is 80μm/135μm/165μm(accuracy±0.7μm).After the final test,16.25%of the qualified fiber products are sampled randomly for high and low temperature aging,and the beat length and crosstalk change little after the experiment.The PM fiber developed in this design has stable performance,precise geometric size,uniform structure,low loss,and excellent polarization maintaining performance,which has been widely used in practical production.