Pre-chirp assisted normal dispersion region transmission for highly marginal dense WDM transoceanic system

Summary form only given. Owing to successive studies and developments of optical devices, technologies for transmitting high-capacity WDM signals (/spl sim/100 Gbit/s) over transpacific length have been established. In these experiments, by developing optical amplifiers with small noise figure, very low signal power was used for suppressing nonlinear effects in the transmission fiber. From the practical point of view, however, transmission with higher signal power is preferable to secure the better optical SNR at the receiver end, and get more margin. We have investigated the measures against two problems, waveform distortion due to SPM-GVD effect and spectrum broadening due to SPM in some channels around the zero-dispersion wavelength (/spl lambda//sub 0/), which appear when the signal power becomes higher. We have confirmed that optimum pre-chirp is quite effective to suppress the waveform distortion due to SPM-GVD effect especially in the normal region. By avoiding the wavelength bandwidth around /spl lambda//sub 0/ and arranging all the channels in the normal dispersion region with channel spacing of 0.4 nm, we have successfully demonstrated 100 Gbit/s transmission over 9,500 km with the repeater output power of -3 dBm/ch.