Polarisation effects in long-haul optically amplified lightwave systems

Long-haul optically amplified lightwave systems show performance degradation due to polarisation effects in the line. These include polarisation dependent gain in erbium-doped fibre amplifiers (PDG), polarisation dependent loss in passive components (PDL) and polarisation mode dispersion in the transmission fibre (PMD). We show experimental and simulation data indicating how the polarisation effects impact system performance and how polarisation scrambling at the transmitter acts to minimise the polarisation-induced penalties.