Investigation of Polarization Dispersion in Long Lengths of Single-Mode Fiber Using Multi-Longitudinal Mode Lasers

We have used multi-longitudinal mode lasers to investigate the ploarization properties of long lengths of single mode fiber cable. We find that the individual longitudinal modes are >99% polarized after propagation through 54.6 km of cabled fiber, however, the different longitudinal modes have different states of polarization at the output. This difference is caused by polarization dispersion, and we estimate a propagation delay difference for the two principal states of polarization to be 0.42 ps in the 54.6 km of cabled fiber.