8×114 Gb/s, 25-GHz-spaced, PolMux-RZ-8PSK transmission over 640 km of SSMF employing digital coherent detection and EDFA-only amplification

Employing PolMux-RZ-8PSK modulation format and coherent detection, we demonstrate 8×114Gb/s DWDM transmission over 640km of SSMF on a 25GHz grid with record spectral efficiency of 4.2bit/s/Hz, utilizing no optical dispersion compensation or Raman amplification.