Abstract

In high-capacity long-haul wave division multiplexed (WDM) systems, the carrier phase is distorted by the fiber non-linearity which, in the presence of dispersion, is converted to amplitude distortion. Consequently, transmission degradation due to fiber non-linearity is most severe when the cumulative dispersion is high. The isolated pulses inherent to the return-to-zero (RZ) format are more tolerant to non-linear effects than the non-return-to-zero (NRZ) format.¹ This has led to the RZ modulation format being used on current submarine systems, achieving record transmission capacities over a transatlantic distance of 6,000 km. ²

© 2002 Optical Society of America