Introduction To Lightwave Systems.

This paper presents an introduction to the principles of lightwave systems. The treatment is historical rather than categorical- lightwave systems are described in terms of their evolution through four generations of technology, from a first generation operating at 0.85micron wavelength over multimode fiber to a fourth generation employing coherent techniques at 1.55microns. Basic engineering considerations such as fiber dispersion and receiver sensitivity are introduced early, then refined as the discussion progresses toward higher-performance, more sophisticated systems. The fundamental mechanisms that limit the performance of a given technology are quantified, and a figure of merit, the product of bit-rate times maximum repeater spacing, is estimated. Values of this product range from about 2 Gb/s km for first-generation technology to roughly 900 Gb/s km for coherent systems. Applications of lightwave technology to multiuser networks are discussed.