Phase noise and polarization state insensitive optical coherent systems

The authors present three different schemes that allow compensation of phase noise and polarisation state change by sending a reference channel that is suitably frequency shifted by using polarization modulation together with Stokes parameters detection or computing and inverting the Jones matrix that describes the fiber polarization state transformation. As a conclusion, some comparisons are made among different approaches in order to show how different systems can be tailored to different requirements both in point-to-point and in multipoint networks.>