On the Effect of Polarisation-Mode Dispersion on the Channel Capacity of Coherent Fibre-optic Communication Systems

Although the value itself is difficult to determine, it is well-known that the channel capacity of fibre-optic communication systems is limited by optical and electrical noise and non-linear effects such as the Kerr effect or the square-law characteristics of the photodiode at the receiver. We investigate the impact of another capacity- degrading fibre-effect, Polarisation-Mode Dispersion (PMD), in single-channel single-span systems with optical amplification and coherent detection. Results for the capacity of PMD-limited channels are derived for first- order and higher-order PMD. As PMD may be considered a slowly-varying effect (in time), the capacity distribution is also discussed.