Dispersion-balanced optical cable

A dispersion-balanced optical cable 90 reduces four-photon mixing in Wave Division Multiplexing (WDM) systems and is effective to reduce cumulative dispersion D substantially to zero. The dispersion-balanced optical cable 90 includes one or more optical fibers 90-1 having positive dispersion D1, and one or more optical fibers 90-2 having negative dispersion D2. The fibers are singlemode and are suitable for the transmission of optical signals in the 1550 nm region. At this wavelength, the positive-dispersion fibers have a chromatic dispersion of about +2.3 ps/nm-km, and the negative-dispersion fibers have a chromatic dispersion of about -1.6 ps/nm-km. The dispersion-balance optical cable preferably includes an equal number of positive- and negative-dispersion fibers in the same cable. Various cable configurations 60, 80, 90 can be used including: a ribbon 60 which comprises a planar array of optical fibers bound together by a matrix material 65; groups of positive- and negative-dispersion fibers enclosed within a plastic tube 81; or other known configurations. An improved WDM system 100 interconnects two dispersion-balanced cables 90-90, and a crossover connection 105 is made between the positive-dispersion fibers 90-1 of one cable 90 and the negative-dispersion fibers 90-2 of the other cable 90.