Long-Haul 40 Gb/s RZ-DPSK Transmission over 4,450 km with 150-km Repeater Spacing using Raman Assisted EDFAs

40Gb/s RZ-DPSK signals were successfully transmitted over 4450km with 150km repeater spacing (33dB span loss) using Raman assisted EDFAs. The performance was compared with EDFA only amplification and 110km repeater spacing. Long-term Q-factor fluctuations were also quantified for Raman-assisted amplification.