Interferometric polarization compensation based on one single polarization-maintaining fiber.

Abstract

In an interferometry system based on one single polarization-maintaining fiber (PMF), defects like the laser's ellipticity, the alignment error between the PMF and the laser source, and the PMF's internal stress will cause the emitted light from the PMF to be incompletely linearly polarized, resulting in nonlinear errors that cannot be ignored. This paper proposes a novel method that can realize polarization compensation for heterodyne interferometry, reduce the ellipticity of the emitted light, and thereby reduce the nonlinear error of the system. When using a PMF with an Extinction Ratio (ER) of 22 dB, the experimental results show that this method can reduce the polarization and increase the ER to 33.95 dB. After polarization compensation, the nonlinear error is reduced from 7.22 nm to 2.02 nm. The proportion of the nonlinear error reduction reaches to 71.99%, which greatly improves the accuracy of the system.