1.28 Tbit/s-70-km OTDM femtosecond-pulse transmission using third- and fourth-order simultaneous dispersion compensation with a phase modulator

By means of the higher-order dispersion compensation technique using a phase modulator, a 70-km transmission experiment with 1.28 Tbit/s OTDM (Optical Time Domain Multiplexing) signals has been successfully conducted for the first time. The details are reported in this paper. The 1.28 Tbit/s signal is obtained by 64-fold multiplexing of 10 Gbit/s signals with additional polarization multiplexing. For the signal pulse with a pulse width of 380 fs prior to transmission, a linear chirp is imparted and then a cosine phase modulation with an appropriate amplitude and the timing is set in such a way that the imparted chirp is opposite to the chirps caused by the third- and fourth-order dispersion in the transmission path. In this way, the waveform distortion of the signal due to the third- and fourth-order dispersion can be suppressed simultaneously. The pulse widening of the signal after transmission over 70 km is only 20 fs. Hence, an error rate of less than 1 × 10^-9 can be realized over the entire channel (10 Gbit/s-128 channels after multiplexing separation.