Impact of Pulse Shaping on the Performance of 112-Gb/s PDM-QPSK Coherent Systems
05 April 2011
The impact of pulse shaping on the performance of 112-Gb/s polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) coherent transmission systems in the presence of narrow bandwidth reconfigurable optical add-drop multiplexers (ROADMs) and fiber nonlinearities is experimentally studied. We show that 112-Gb/s PDM-QPSK signals with carrier-suppressed return-to-zero (CSRZ) and return-to-zero (RZ) pulse shapes have better tolerance to ROADM filtering than that with non-return-to-zero (NRZ) pulse shapes. We find that in a long haul transmission system with ROADMs and fiber nonlinearities, time-interleaved RZ- (iRZ-) and iCSRZ-PDM-QPSK outperform NRZ-PDM-QPSK, with iCSRZ-PDM-QPSK achieving the best performance.
