PDL Impact on Linearly Coded Digital Phase Conjugation Techniques in CO-OFDM Systems

TL;DR

This paper examines how polarization-dependent loss affects digital phase conjugation techniques in CO-OFDM systems, comparing two approaches and analyzing their robustness under different PDL models.

Contribution

It provides a comparative analysis of two DPC methods under PDL conditions, highlighting their relative robustness and outage probabilities in optical communication systems.

Findings

The second DPC approach is more PDL-tolerant than the first.

Outage probability approaches zero at 3.6 dB RMS PDL for the second approach.

The first approach has a 0.63 outage probability at the same PDL level.

Abstract

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.