WDM long haul transmission systems

Summary form only given. Wavelength-division multiplexing techniques in combination with erbium-doped fiber-amplifers will allow for the second "order-of-magnitude" capacity increase for long-haul transmission systems within the past few years. This tutorial will review important issues regarding the use of WDM in long-haul lightwave systems. The transmission of many WDM channels over long distances can be limited by a variety of added phenomena, including the finite bandwidth of the EDFA repeaters, the nonlinear interactions between channels, and the noise accumulation along the chain of amplifiers. Large transmission capacity enhancements have resulted from an increased understanding of these effects. Important strides have been made in areas of dispersion management, gain equalization, and modulation formats, which have made possible the demonstration of large data transmission capacity.