PREFACE

Fiber optic communications developed very quickly after the first low-loss fibers were produced in 1970. Operational fiber systems are now common, and new installations and applications appear continually. This growth is expected to continue for many years.

Although still evolving, fiber technology has matured sufficiently so that many books have been written on the subject. Many of them are quite detailed in terms of theoretical and mathematical content, and the beginner may find the level difficult.

This text is intended to be less difficult, while still bringing to the reader the information necessary to understand the design, operation, and capabilities of fiber systems. Important theoretical and mathematical results are given without the accompanying lengthy proofs. However, results are explained in physical terms when possible and appropriate, and extensive tables and figures are used to make those results readily usable. To provide a realistic view, numerical values are given for the range of typical device parameters.

When the first edition of this book appeared in 1984, fibers had already criss-crossed much of the United States and many others countries to deliver telephone messages between the major exchanges. By 1988, when the second edition was published, the land-based long-distance fiber telephone network was nearly complete, and submarine fiber telephone cables were being installed beneath the major oceans. In addition, fiber optic local-area networks (LANs) were in development. When the third edition went to press, over 10 million kilometers of fiber had been installed worldwide, numerous submarine fiber cables covering the Atlantic and Pacific oceans and many other smaller seas were operational, and installation of fiber LAN’s was increasing. In addition, numerous tests had been completed for bringing fiber to all homes, holding the promise for expanded services to the individual subscriber. This continuing development will involve huge amounts of fiber, tremendous numbers of associated components, and a significantly large work force trained to implement it. Some projections foresee the goal being met sometime early in the next century.

It is the continued growth and evolution of the fiber industry that makes this new edition necessary. The fundamentals have not changed, but many new components and techniques are available for applying fibers to communications problems. I have attempted to work these new ideas into the previous edition with as little disruption as possible.

This is an introductory book. No background in fiber optics, or optic communications, is presumed. Only the simplest concepts from algebra and trigonometry are invoked in explaining the characteristics of fiber systems. Appropriate background material on optics, electronics, and communications is introduced in the text as needed.

This book is based on a set of notes I developed and used for numerous short courses on fiber optic communications. Participants in these courses had training ranging from two years of technical school through the Ph.D. level. Jobs varied from designer to board chairman. Attendees included personnel from industry, government, and academia. Individual backgrounds were in chemistry, physics, and many areas of engineering. In addition to the short course presentations, I have taught this material to over one thousand electrical engineering students at the senior and first-year graduate level.

The professionals benefiting from this book include practicing design engineers concerned with the selection and application of components and with the design and evaluation of systems. Knowledge of the entire system is useful for the device designer as well. Others involved in fiber optics, such as high-level engineering decision makers, project managers, technicians, marketing and sales personnel, and teachers, can also obtain valuable information from the material presented.

The organization of the book is as follows. Block diagrams of entire fiber optic systems are presented at the outset. This identifies the components of fiber systems, providing motivation for their individual study in succeeding chapters. Chapters 2 and 3 contain a review of important results from the fields of optics and wave travel. This basic information is needed for an understanding of fiber optic devices and systems. Chapter 4, on integrated optics, introduces the technology of combining optic components onto a single substrate. The integrated-optic waveguide provides an excellent, simplified model for propagation of light in a fiber. Chapters 5-9 present the main devices encountered in a fiber optic system. These are the fiber, light source, light detector, couplers, and distribution networks. System considerations appear in Chapters 10-12, where modulation formats, the effects of noise on message quality, and system design are covered. The last chapter includes examples of operational systems. In this chapter, the design information developed throughout the book is applied to realistic problems.

I expect the reader who has mastered this material to be able to design and specify systems and to choose and evaluate system components such as fibers, light sources, detectors, and couplers. Commercially available subsystems, such as complete transmitters and receivers, will also be amenable to evaluation by the techniques presented in this book.

This new and fully revised edition of Fiber Optics Communications incorporates significant advances made in the fiber industry since publication of the third edition. Because the fundamentals of the technology have remained the same, the number of changes is moderate. Nonetheless, the changes and additions are significant. Added or expanded topics include: fiber lasers and amplifiers, vertical-cavity surface-emitting laser diodes, dense wavelength-division multiplexing, fiber Bragg grating technology, new component descriptions (fiber attenuator, circulator, and polarization controller), new phenomena descriptions (polarization mode dispersion, mode-partition noise), power penalty, expanded discussion of polarization effects in fiber systems, added material on integrated optic components, and an expanded section on practical fiber connectors and how to minimize reflections. In addition, the discussions in a number of sections were modified to improve clarity of the presentation.

Because numerous colleges adopted the initial text for an undergraduate course in fiber optics, a homework problem set was inserted in the second edition. New problems have been added and several of the old ones have been updated for this new edition, making this text’s use in the classroom even more desirable. Some problems are merely "plug-in"-type questions intended to give the student practice and confidence in understanding the material presented. Other problems take more thought and may even require finding and reviewing material from other sources. Answers to most problems appear at the end of the book, and a new solutions manual is available for instructors.

The bibliography and periodicals listing at the end of the text provides a resource for further study. Sixty-nine books have been added to the list, all published since 1991. The large number of new books attests to the continued growth, change, and interest in fiber optics.

I find that the first seven chapters can be covered in a one-semester course. This introduces all the major system components to the students, allowing those who have mastered the material to productively enter into the fiber industry. The last five chapters, on more advanced topics, can be covered in a second term. To simplify the mathematics and reach a wider audience, many of the results presented in the text are not fully derived. Instructors of well-prepared students, such as seniors in electrical engineering programs, may wish to fill in the derivations to deepen student understanding.

FIBER OPTIC SOFTWARE

For some time now, all technical workers and students have had access to personal computers and the Internet. Because of this, many groups have developed software to illustrate fiber-related phenomena and to aid analysis and design. Several such programs are available through my home page (www.eas.asu.edu/~palais/). In addition, there is an interactive digital design package that provides complete automatic design synthesis based on user-supplied system performance criteria. It has many features of an expert system. This package was developed by one of my former graduate students. For further details contact C.S. Bergstrom, 501 South Oak, Chandler, AZ 85226, or email at: bergstr0m@aol.com.

ACKNOWLEDGEMENTS