Novel bidirectional path measurement of polarization cross-coupling distribution in PMF

Abstract

The measurement accuracy of polarization cross-coupling strength based on white-light interferometry obviously decreases in long-distance polarization maintaining fiber (PMF), due to the difference of dispersion between two eigenmodes (birefringence dispersion). In this paper, we demonstrate a bidirectional measurement method with the scheme including a polarization maintaining coupler, a magnetic optical circulator and an Optical Coherence Domain Polarimeter (OCDP). The experiment setup and results are described in detail. The cross-coupling distribution results from each direction measurement were processed to mitigate the influence of dispersion. The compensation is conducted on coupling strength results, instead of raw interference signal in traditional method. The method saves the investigation of birefringence dispersion coefficient and light source parameters compared with compensation in frequency domain. Our experiment with a PMF coil of 200m length demonstrates the effectiveness in improving strength accuracy with absolute deviation less than 0.31dB, and spatial resolution recovered to 8.4cm.