  We investigate the impact of polarization-dependent loss (PDL) on the
linearly coded digital phase conjugation (DPC) techniques in coherent optical
orthogonal frequency division multiplexing (CO-OFDM) superchannel systems. We
consider two DPC approaches: one uses orthogonal polarizations to transmit the
linearly coded signal and its phase conjugate, while the other uses two
orthogonal time slots of the same polarization. We compare the performances of
these DPC approaches by considering both aligned- and statistical-PDL models.
The investigation with aligned-PDL model indicates that the latter approach is
more tolerant to PDL-induced distortions when compared to the former.
Furthermore, the study using statistical-PDL model shows that the outage
probability of the latter approach tends to zero at a root mean square PDL
value of 3.6 dB. On the other hand, the former shows an outage probability of
0.63 for the same PDL value.
