40-Gb/s RZ transmission over transoceanic distance in a dispersion managedstandard fiber using a new inline synchronous modulation method

We propose a modified soliton control method for a strongly dispersion mana ged line, which employs a highly non-linear fiber in addition to convention al inline synchronous modulation. This method enables us to transmit a 40-G b/s return-to-zero signal over 20 000 km using a dispersion managed line co mposed of a standard (nondispersion shifted) fiber and dispersion compensat ion. Optimizing the length of the highly nonlinear fiber greatly increases the power margin of the transmitted optical power.