Optical Transport Network

Different linear effects that occur in the physical medium are studied and analyzed in this chapter. Specifically, much attention is paid to fiber attenuation, Amplified Spontaneous Emission (ASE) noise due to optical amplifiers, and fiber dispersive effects that cause pulse broadening, which may represent a serious problem in high-speed optical transmission systems. In order to reduce fiber dispersive effects effectively, dispersion compensation fiber is employed. Other effects such as linear crosstalk, which causes distortion and interferes with the filtered channel, can be reduced by optimizing the optical filter bandwidth and shape to obtain a compromise between WDM linear crosstalk and filter induced intersymbol interference (ISI).