Spectrally Efficient DP-1024QAM 640 Gb/s Long Haul Transmission using a Frequency Comb

We experimentally investigate the long haul transmission of an 8 GBd DP-1024QAM over fully Raman amplified fiber spans using an optical frequency comb. We reach a potential spectral efficiency of 8.7 bit/s/Hz at 3000 km transmission and a potential data rate of 640 Gb/s.