4000km transmission of 50GHz spaced, 10×494.85-Gb/s hybrid 32–64QAM using cascaded equalization and training-assisted phase recovery

Employing time-domain hybrid QAM, training-assisted phase recovery and cascaded equalization, we successfully transmitted ten 494.85Gbit/s PDM-32/64QAM DWDM signals at 8.25b/s/Hz net spectral efficiency (SE) over 40×100km, achieving a record terrestrial SE⋅distance product of 33,000-km b/s/Hz.