Narrowband 640 Gbit/s soliton DWDM transmission over 1200 km of standard fibre with 100 km -21 dB amplifier spans

640 Gbit/s (32/spl times/20 Gbit/s) soliton dense wavelength division multiplexing (0.4 nm channel-spacing) transmission over 1200 km with 100 km dispersion-compensated spans of standard step-index fibre is demonstrated.