645-Gbit/s/carrier PS-16QAM WDM Coherent Transmission over 6,800 km Using Modified LSTM Nonlinear Equalizer

We experimentally demonstrated a 645-Gbit/s/carrier WDM coherent transmission over 6,800-km based on 106-Gbaud PS-16QAM by utilizing modified PS-suitable LSTM-NLE. Our results show that 55% reach improvement is obtained by LSTM-NLE. We also compared performance and computational complexity of LSTM-NLE, Bi-LSTM-NLE and VNLE.