Principle of preparation and parameters test of polarization-maintaining fiber

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 6.26 μm, NA is 0.23, and cladding and coating diameter is 80 μm/135 μm/165 μm (accuracy ±0.7 μm). 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.