PMD outage probabilities of optical fiber transmission systems employing bit-to-bit alternate polarization

The impact of differential group delay (DGD), induced by polarization-mode dispersion, on the performance of differential phase-shift keyed and on-off keyed modulation formats employing bit-to-bit alternate polarization (APol) is investigated by means of numerical simulation. Thereby, it is observed that the optical signal-to-noise ratio (OSNR) penalty due to DGD is almost independent of the power splitting ratio between the principal states of polarization (PSP) of a DGD emulator, when APol modulation formats are employed. Although this leads to a higher mean OSNR penalty for a given DGD value compared to conventional modulation formats, it is shown that the allowed mean DGD for required low system outage probabilities does not change significantly.