Comparison of 64 × 10 Gb/s NRZ and RZ transmission over 6,000 km using a dispersion-managed fiber solution

We have demonstrated NRZ transmission of 64 channels at 10.664 Gb/s over 6,000 km using a dispersion-managed fiber solution with a sufficient margin to make this a viable option for future submarine systems. This has been made possible by the very low dispersion slope and hence cumulative dispersion achieved using DMF. The NRZ transmitter, which only requires a single modulator, is simpler to implement than the RZ transmitter, thus reducing the terminal complexity and cost. NRZ is also more spectrally efficient, offering the possibility of closer channel spacing than with RZ. Overall, the higher peak powers for the RZ format meant that this format performed 0.75 dB better than NRZ.