500 Gb/s (50 x 10.66 Gb/s) WDM transmission over 4000 km using broad-band EDFA's and low dispersion slope fiber

500 Gb/s (50/spl times/10.66 Gb/s) over 4000-km, error-free transmission was demonstrated with 22 nm-bandwidth Er-doped fiber amplifiers (EDFA's) and low dispersion slope NZ-DSF fiber. We reduced the span average dispersion slope and fiber nonlinearity by optimizing the combination ratio of large-core fiber (LCF) and NZ-DSF, and the transmission distance was almost doubled compared to the previous experiments of similar capacity using conventional NZ-DSF.