The rapidly growing importance of optical fibers as a communications medium has been accompanied by a steady improvement of the theoretical understanding of their properties. In the beginning, basic physical and mathematical principles allowed only a rough description of fiber behavior. Later on, more precise theories were developed, but most of them are highly complex and can only be used by specialists, and their apparent accuracy is not always supported by the achievable precision of parameter measurements. Eventually, more realistic theories evolved (influenced by the growing knowledge of physical effects in fibers) which could be used more easily and which were nevertheless of sufficient accuracy. This book concentrates on these types of methods, some of which are not yet generally known, because they are of particular interest to engineers and students
of communications, for whom it was mainly written.