high-order PMD can, at least for some input SOPs, lower the penalty in compar-
ison with the first-order only case [45, 52]. Although the solid line in Figure 17.16
serves as a lower bound for the high-order data for this particular receiver, that
does not seem be a unive rsal rule. Summarizing the reviewed experiments and
simulations, we conclude that the principal contribution to PMD-induced OSNR
penalties comes from first-order PMD.
Although PMD-compensated systems seem to be far from the deployment
stage, several groups have investigated PMD penalties and outages in such systems
[52, 53, 58]. In particular, one concept was tested: Can PMD penalties in systems
with compensated first order be described by the second order only? Such a
hypothetical ...