80 Gbit/s-1200 km, 40 Gbit/s-based WDM transmissionexperiment using RZ pulse format

Abstract
The successful two-channel WDM transmission of optically multiplexed 40 Gbit/s RZ signals with properly managed fibre dispersion is demonstrated. The dispersion dependence of the signal-to-noise-ratio for each signal channel is measured and it is found that the optimum total dispersion value, including dispersion compensation fibres, is not zero but is anomalous, which is slightly smaller than the value predicted by the soliton condition with uniform dispersion.