Fourth-order dispersion compensation for 250-fs pulse transmission over 139-km optical fiber

Record distance transmission of 250-fs pulses over 139-km optical fiber at 6-GHz repetition is realized by compensating chromatic dispersion up to fou rth-order using a novel approach. The link is designed combining 108.5-km s tandard single-mode fiber (SMF), 17.5-km dispersion-shifted fiber, and 13-k m negative-slope dispersion-compensating fiber to achieve both zero total c hromatic dispersion and slope at the 1.55-mu m carrier. Fourth-order pulse dispersion caused by the fiber dispersion curvature around 1.55 mu m is the n suppressed by adding the quadratic phase of opposite sign from excess SMF to produce 503-fs output. However, both higher quality and shorter 390-fs output is achieved after applying 6-GHz electrooptic phase modulation (3.5 pi 0-peak) to prestretched pulses and adding a further 50-m SMF to the link .