Transmission of 2.5 Gb/s WDM Channels Spaced at 5 GHz over 480 km of Single Mode

We demonstrate the transmission of 2.5-Gb/s WDM signals spaced at 5 GHz over 480 km of single-mode fiber. The results indicate that it should be possible to transmit more than one thousand 2.5-Gb/s channels spaced at 5 GHz over long distance.