PMD pre-distorted signals for reducing nonlinear intra-channel caused impairments

Summary form only given. The maximum reach of ultra-longhaul on-off keying transmission systems is mainly limited by the three length dependent parameters: CSNR degradation, nonlinear (NL) signal distortion, and fiber polarization mode dispersion (PMD) (in the case of 40 Gb/s per channel systems). The penalty arising from nonlinear effects depends strongly on the link design, while the penalty caused by PMD is related (in the case of linear signal propagation), to the intrinsic fiber PMD and the specific signal modulation format. It is the goal of system engineering to allocate adequate margin for each penalty source such that the system range is maximized under the constraint that the total penalty is covered by the link budget. Here we show for the first time that under certain circumstances the total penalty from nonlinear effects and PMD can be less than the sum of the two individual penalties. Indeed, we demonstrate that a PMD pre-distorted signal suffers less nonlinear signal perturbations. Ultra-longhaul 40 Gb/s systems (per channel) will need PMD compensation even when running over low PMD fiber. Thus, a post compensation of the pre-PMD distortion requires no significant add-ons in the system architecture.