STABILITY IN DISTRIBUTED AND LUMPED GAIN TRANSMISSION-SYSTEMS

In ultralong transmission based on cascade-coupled optical amplifiers the limitations in bit rate are found in systems that use lumped as well as distributed gain, with nonlinearities taken into account. For lumped gain, pulse distortion is highly decreased when the repeater distance relative to the dispersion length is less than 0.1. For distributed amplification the lowest pulse distortion is achieved when the distance between two pump stations, relative to the dispersion length, is less than 0.5. We consider not only stability but also noise accumulation.