Over 1000 km FSK heterodyne transmission system experiment using erbium-doped optical fiber amplifiers and conventional single-mode fibers

The influence of spontaneous emission noise on coherent transmission systems using multistage erbium-doped optical fiber amplifiers is experimentally examined. A frequency-shift keying (FSK) heterodyne transmission experiment was successfully performed at 560 Mb/s through 1028 km of fiber using ten cascaded fiber amplifiers and conventional single-mode fibers with a zero dispersion wavelength of around 1.3 mu m. In the experiment, no transmission penalty due to accumulated spontaneous emission noise or to fiber chromatic dispersion was observed.>