Introduction to the issue on modeling of high data rate optical fiber communication systems

Abstract

In the last five years, there has been a revolution in optical fiber communication systems due to the advent of wavelength-division multiplexing (WDM). The carrying capacity of optical fiber systems has increased from gigabits per second to over a terabit per second in the laboratory. The lag between laboratory demonstrations and commercial development has been reduced to approximately two years. These changes have been accompanied by a significant increase in the complexity of network elements, particularly the line terminals and the amplifiers, as well as new fiber designs and new, increasingly sophisticated network topologies. The increasing use of foward error correction also adds to system complexity. As the number of channels increases, the economic demand for fewer terminals forces designers to use higher single-channel data rates. At data rates of 10 Gb/s and, soon, 40 Gb/s, the behavior of the signal as it propagates through an optical fiber communication system is far from linear or intuitive. Consequently, the transmission line, amplifiers, and attendent compenents must be much more carefully designed than was the case in the past. Modern-day telecommunications companies rely heavily on numerical modeling to design their systems since the complexity of today’s optical fiber transmission networks precludes complete reliance on simple analytical treatments. Numerical models are used to lay out network topologies, identify design spaces for dispersion maps and amplifiers, and to refine designs of passive and active components. System modeling prior to laboratory implementation and field trials has become increasingly widespread because it reduces both the cost and the time for the development cycle. Given the practical importance of this subject, it surprises newcomers to the field to learn that the number of experts in