12,000km transmission of 100GHz spaced, 8 495-Gb/s PDM time-domain hybrid QPSK-8QAM signals

Employing time-domain hybrid QPSK-8QAM and training-assisted phase recovery, we successfully transmitted eight 495-Gb/s DWDM signals at net 4.125 bit/s/Hz spectral efficiency (SE) over 120×100km of ultra-large-area fiber, achieving a record SE distance product of 49500 (bit/s/Hz)km.