First Quantitative Determination of Birefringence Variations Induced by Axial-Strain in Polarization Maintaining Fibers

Abstract

We report what we believe to be the first quantitative determination of strain-induced birefringence variations in polarization maintaining fibers (PMFs). The measurement method is based on the ghost-peak-free scanning white light interferometer based distributed polarization crosstalk analysis technique with two fusion-splicing-induced polarization crosstalk reference peaks, as the strain-induced birefringence variation causes a change of the spacing between the two peaks. Two types of commercial PMF samples (Panda and Bow-tie) are measured and the experimental data are fitted to a linear equation using the least squares method with a high goodness of fit. The strain coefficients of birefringence $1.60 \times {10^{ - 8}}/\mu \varepsilon $ and $1.06 \times {10^{ - 8}}/\mu \varepsilon $ are obtained for the Panda and Bow-tie PMFs, with uncertainties of 4.84% and 7.81%, respectively. Our error analysis indicates that the measurement uncertainty can be readily reduced to be less than 1% if the accuracy of the variable delay line used in the interferometer of the distributed polarization crosstalk analyzer can be improved to be ≤0.6 μm and the temperature variations can be compensated in final calculations by actively monitoring the temperature during the measurement.