The impact of polarization mode dispersion: optical duobinary vs. NRZ transmission

The optical duobinary data-coding is a promising technology for the implementation of ultra-dense WDM (UDWDM) systems with spectral efficiency close to the Nyquist limit. In recent experiments at 40 Gbit/s the efficiency of 0.8 bit/s/Hz has been demonstrated. Working at a bit rate as high as 40 Gbit/s the PMD could strongly impair system performance. The purpose of this work is to compare the impact of PMD on optical duobinary with respect to its impact on NRZ in a OC-768 FEC-inclusive scenario requiring an actual line-rate of 42.65 Gbit/s. We demonstrated that the impairment of PMD is larger on duobinary than on NRZ systems. However, due to its better intrinsic performance, the use of duobinary may still produce convenient results in some scenarios, like the ones analyzed.