40-Gb/s return-to-zero alternate-mark-inversion (RZ-AMI) transmission over 2000 km

We report on the transmission of 40-Gb/s alternate-mark-inversion return-to-zero (RZ-AMI) signals over more than 2000 km (20 /spl times/ 100 km) of nonzero dispersion fiber at a bit-error ratio of 10/sup -9/. The RZ-AMI signal is generated using a single, nonreturn-to-zero-driven modulator in combination with an optical delay interferometer. This transmitter allowed for a 40-Gb/s record receiver sensitivity of 78 photons/bit.