IM-DD long-distance multichannel WDM transmission experiments usingEr-doped fiber amplifiers

We have demonstrated multichannel wavelength-division multiplexed optical signal transmission experiments employing Er-doped fiber amplifiers. Four-channel transmission of 459 km and 1500 km experiments and two-channel transmission of 4550 km experiment are described, and the transmission penalty is analyzed. We also discuss the effect of four-wave mixing. The difference of the transmission fiber clearly shows the difference of the optical spectrum due to four-wave mixing after long-distance transmission. The results show the possibility of long-distance multidestination optical communication systems with wavelength-division multiplexed signals combined with Er-doped fiber amplifiers