PMD mitigation and receiver optimization to reduce PMD influence

The statistical distribution of the polarization mode dispersion (PMD) in a recirculating loop has been investigated and an analytical expression of the accumulated differential group delay (DGD) has been derived. It was found that the accumulated PMD-vector evolves spirally through Stokes space and the accumulated DGD becomes uniformly distributed as the number of circulations increases. The expectation value of the DGD increases linearly with the number of circulations through the loop, in contrast to a straight line transmission link, where the expectation value of the DGD grows as the square-root of the link length.