Understanding Fiber Optics / Edition 5

Fiber optics has come a long way since I wrote the first edition of Understanding Fiber Optics. Optical-fiber communications was a radical new technology then, used mostly for high-capacity, long-distance transmission of telephone signals. As I finish the fourth edition, I can look out my office window and see a fiber cable that carries telephone, Internet, and cable-television signals down the street.

Over the years, I have been greatly impressed by the tremendous progress in developing practical fiber-optic equipment. The technology is interesting and elegant, as well as important. I find myself caught up in the advancing field, like a sports writer covering a team blazing its way to a championship. The thrill of technical achievement can be just as tangible to those of us involved with engineering or technology as the thrill of victory is to an athlete.

Although I wrote the first edition mainly for self-study, the book is now used in classroom settings. My goal is to explain principles rather than to detail procedures. When you finish this book you should indeed understand fiber optics. You should be able to pick up a trade journal such as Lightwave or Fiberoptic Product News and understand what you read, just as you should be able to understand the duties of a fiber engineer, a network planner, or a cable installer. You will not be able to do their jobs, but you will be literate in the field. Think of this as Fiber Optics 101, a foundation for your understanding of a growing technology.

To explain the fundamentals of fiber optics, I start with some ideas that may seem basic to some readers. When introducing a relativelynew field, it is better to explain too much than too little.

To make concepts accessible, I include drawings to show how things work, limit the mathematics to simple algebra, and step through some sample calculations so you can see how they work. I compare fiber optics with other common technologies and highlight similarities and differences, and I have also organized the book to facilitate cross referencing and review of concepts.

The book is structured to introduce you to basic concepts first, then to dig deeper into fiber hardware and its applications. The chapters are organized as follows:

• The first three chapters present an overview, starting with a general introduction in Chapter 1. Chapter 2 introduces optics, light, and the concept of light guiding. Chapter 3 introduces communication systems and fiber-optic transmission. These chapters assume you have little background in the field, but they are worth reading even if you think your background is adequate.
• Chapters 4 through 8 cover optical fibers, their properties, and how they are assembled into cables. The material is divided into five chapters to make it easier to digest. Chapters 4 through 6 are essential to understanding the fiber concepts found in the rest of the book. Chapter 7 covers special-purpose fibers used in fiber amplifiers, fiber gratings, and a few odd applications such as architectural lighting. Chapter 8 is an overview of cabling.
• Chapters 9 through 12 cover laser and LED light sources, optical transmitters, optical detectors, receivers, optical amplifiers, and electro-optic regenerators. Chapter 12 compares and contrasts the operation of optical amplifiers and electro-optic regenerators.
• Chapters 13 through 16 cover a range of other components used in fiber-optic systems. Chapter 13 covers connectors and splices that join fibers. Chapter 14 covers optical couplers and other passive components used in simple fiber systems. Chapter 15 covers the optics used in wavelength-division multiplexing, which combine and separate signals at different wavelengths sent through the same fiber. Chapter 16 covers optical modulation and optical switching, key components for optical networking.
• Chapter 17 covers the fundamentals of optical and fiber-optic measurements, and describes how optical measurements differ from those of other quantities. Chapter 18 follows, covering fiber-optic test equipment and troubleshooting.
• Chapters 19 through 22 cover principles of fiber-optic communication. Chapter 19 describes the basic principles behind fiber-optic systems and optical networking. Chapter 20 covers major communication standards. Chapter 21 outlines the design of point-to-point single-wavelength systems, with sample calculations, so you can understand how these systems are put together. Chapter 22 extends design concepts, covering wavelength-division multiplexing and the emerging optical network.
• Chapters 23 through 27 cover various aspects of telecommunications, explaining how fiber optics fit into networks used for global and regional telephone and Internet transmission, cable television, and data networks. These chapters focus on different levels and aspects of the global network to keep concepts manageable. Chapter 28 covers special systems that don't fit elsewhere, such as fiber-optic cables for remote control of robotic vehicles, and networks in aircraft and automobiles.
• The final two chapters describe noncommunication applications. Chapter 29 explains the principles and operation of fiber-optic sensors. Chapter 30 covers imaging an illumination with fiber optics.

Most chapters include suggestions for further reading, and a list of resources appears at the back of the book. Links to Web sites are currently being added to my Web site, http://www.fiberhome.com. I would welcome any suggestions or comments you might have; please e-mail me at jeff@fiberhome.com or fiber@jeffhecht.com.

The glossary at the back of the book gives you quick translations of specialized terms and acronyms.

This edition also includes appendices that tabulate useful information, such as the values of important physical constants, conversion factors, standard data rates and wavelengths, and a few key formulas.

I have tried to make everything current, but the technology is advancing so fast that some details are bound to become obsolete. When you finish Understanding Fiber Optics, you should be prepared to follow the new advances, and perhaps contribute to them as well.

Acknowledgments

Over the years, many people in the fiber-optics industry have given generously of their time to patiently answer my questions. I owe special thanks to Kevin Able, Bill Chang, Erich Dzakler, Jim Hayes, Dennis Horwitz, Jim Masi, Nick Massa, Jim Refi, and Wayne Siddall for reviewing parts of this edition, clearly explaining complex concepts, and pointing me to useful resources. Prentice Hall reviewers Richard J. White, ITT Technical Institute; Stanley M. Krause, St. Philip's College; Kenneth E. Windham, Nash Community College; and Dr. Jalil Moghaddasi, City University of New York Bronx Community College also provided helpful feedback for this edition. David Charlton, Marc Duchesne, Robert Gallawa, Mike Pepper and John Schlager helped with earlier editions. I thank my editors at Prentice Hall, Laser Focus World, and Integrated Communications Design for patience with me above and beyond the call of duty. I also thank the companies, universities, and individuals who posted papers, application notes, tutorials, standards, and data sheets on the World Wide Web where I could find them when questions arose outside normal working hours. And very special thanks to anyone whose names and contributions may have slipped through my haphazard mental filing systems. Any errors that remain are my own.

This book is dedicated to the memory of Heather Williamson Messenger, gifted editor, friend, and victim of domestic violence.

Jeff Hecht