Influence of Pulse Shape in 112-Gb/s WDM PDM-QPSK Transmission

In this work, we investigated the influence of pulse shape on the transmission performance of polarization-division-multiplexed quadrature-phase-shift keying modulation format at 112 Gb/s in a ten-channel wavelength-division-multiplexed (WDM) transmission experiment with 50-GHz channel spacing. Nonreturn-to-zero (NRZ) and return-to-zero with 50% duty cycle (RZ50) were compared. RZ50 was found to have better performance in both single-channel and WDM experiments. Compared with NRZ, the use of RZ50 yielded an increase in reach from 6560 to 7760 km in the single-channel experiment (corresponding to an increase in reach by 18%); in the case of WDM. the reach was extended from 5920 to 7360 km (corresponding to a 24% increase in reach).