Demonstration of 80 Gbit/s WDM transmission over 537 km of non-zero dispersion shifted fibre without in-line dispersion management or gain-tilt equalisation

We have demonstrated 4/spl times/20 Gbit/s WDM transmission over 537 km of non-zero dispersion shifted fibre. The sensitivity of all channels for a BER of 10/sup -9/ was between -27.9 and -27.2 dBm (2/sup 31/-1 PRBS). The experimental system was based on a typical amplifier spacing of 75 to 80 km and operated with moderate amplifier powers of 9 to 10 dBm total. FWM cross-talk and MI noise amplification were largely suppressed by using commercial NZ-DSF with red-shifted /spl lambda//sub 0/ values. The total wavelength span was only 6 nm, and there was no need for gain-tilt equalisation or dispersion compensation within the line. This potentially enables system installation on pre-existing fibre just by upgrading the line terminals.