640 GBd Phase-Correlated OTDM NRZ-OOK Generation and Field Trial Transmission

We generate a 640 GBd phase-correlated optical time-division multiplexed (PC-OTDM) return-to-zero ON-OFF keying (RZ-OOK) signal based on cross-phase-modulation-induced cross-polarization rotation in an Al highly nonlinear fiber and a 640 GBd PC-OTDM nonreturn-to-zero (NRZ)-OOK signal by RZ-to-NRZ conversion using passive filtering. This is employed in a 1.19 Tb/s PDM-NRZ-OOK field transmission with BER <; 3.8 × 10
^-3
for all 128 tributaries. As a benefit of phase coherence between adjacent TDM channels, a PC-OTDM signal can be very tolerant to strict filtering and the bandwidth of the 640 GBd PC-OTDM NRZ-OOK signal can be restricted to 700 GHz. In addition, with a narrower spectrum a PC-OTDM NRZ-OOK signal is more tolerant to chromatic dispersion and polarization-mode dispersion compared to a conventional (i.e., phase-uncorrelated) OTDM RZ signal.