Table of Contents

Preface

1 An Introduction to Fiber Optics

A Personal View: Ups and Downs

The Roots of Fiber Optics

The Very Basics of Communications

Fiber Terms: Terminology and Units

2 Fundamentals of Fiber-Optic Components

Basics of Optics

Light Guiding

Fiber Transmission

Electro-Optics and Other Components

Fiber-Optic Applications

3 Fundamentals of Communications

Communications Concepts

Signals and Formats

Connectivity

Communications Services

The Business of Telecommunications

4 Types of Optical Fibers

Light Guiding

Step-lndex Multimode Fiber

Modes and Their Effects

Graded-lndex Multimode Fiber

Single-Mode Fiber

Dispersion-Shifted Single-Mode Fiber

Polarization in Single-Mode Fiber

Other Fiber Types

5 Properties of Optical Fibers

Fiber Attenuation

Light Collection and Propagation

Dispersion

Nonlinear Effects

Mechanical Properties

6 Fiber Materials, Structure, and Manufacture

Requirements for Making Optical Fibers

Glass Fibers

Fused-Silica Fibers

Plastic Fibers

Exotic Fibers and Light Guides

7 Specialty Fibers

What Are "Specialty" Fibers?

Dispersion-Compensating Fibers

Polarization-Maintaining Fibers

Bend-Insensitive and Coupling Fibers

Reduced-Cladding Fibers

Doped Fibers for Amplifiers and Lasers

Fiber Gratings and Photosensitive Fibers

Photonic or "Holey" Fibers

Special Noncommunications Fibers

8 Cabling

Cabling Basics

Reasons for Cabling

Types of Cable

Elements of Cable Structure

Cable Installation

Cable Changes and Failure

9 Light Sources

Light Source Considerations

LED Sources

The Laser Principle

Simple Semiconductor Lasers

Laser Wavelength

Fiber Lasers

Other Solid-State Laser Sources

10 Transmitters

Transmitter Terminology

Operational Considerations

Multiplexing

Modulation

Single-Channel Transmitter Design

Sample Transmitters

11 Receivers

Defining Receivers

Performance Considerations

Electronic Functions

Sample Receiver Circuits

12 Amplification, Regeneration, and Wavelength Conversion

Amplification and Regeneration

System Requirements

Repeaters and Regenerators

Optical Amplifiers

Erbium-Doped Fiber Amplifiers

Other Doped Fiber Amplifiers

Raman Amplification in Fibers

Semiconductor Optical Amplifiers

Wavelength Conversion

13 Connectors and Splices

Applications of Connectors and Splices

Fiber-to-Fiber Attenuation

Internal Reflections

Mechanical Considerations in Connectors

Connector Structures

Standard Connector Types

Splicing and Its Applications

Splicing Issues and Performance

Types of Splicing

14 Couplers and Other Passive Components

Coupler Concepts and Applications

Coupler Characteristics

Coupler Types and Technologies

Attenuators

Optical Circulators

15 Wavelength-Division Multiplexing Optics

WDM Requirements

WDM Systems

Optical Filters and WDM

WDM Technologies

Building Multiplexers and Demultiplexers

16 Optical Switches, Modulators, and Other Active Components

Defining Active Components

Modulators and Modulation

Optical Filters and WDM

Wavelength Switching and Conversion

Integrated Optics

17 Fiber-Optic Measurements

Basics of Optical Power Measurement

Wavelength and Frequency Measurements

Phase and Interference Measurements

Polarization Measurements

Time and Bandwidth Measurements

Signal Quality Measurements

Fiber-Specific Measurements

18 Troubleshooting and Test Equipment

Fiber-Optic Troubleshooting

Test and Measurement Instruments

Troubleshooting Procedures/dd>

19 System and Optical Networking Concepts

An Evolving Network

Telecommunication Network Structure

Transmission Topologies

Directing Signals

Signal Formats

Transmission Capacity

20 Fiber System Standards

Why Standards Are Needed

Families of Standards

Layers of Standards/dd>

Interchange Standards

Fiber Transmission Standards

Current Standards Issues

21 Single-Channel System Design

Variables

Power Budgeting

Examples of Loss Budgeting/dd>

Transmission Capacity Budget

Cost/Performance Trade-offs

22 Optical Networking System Design

Optical Networking Concepts

Optical Channel Density

Operating Ranges of WDM Systems

Factors in WDM Design

Optical Amplification and WDM Design

Switching and Optical Networking

Design Examples

23 Global Telecommunications Applications

Defining Telecommunications

The Global Telecommunications Network

Internet Transmission

Submarine Cables

Long-Haul Terrestrial Systems

Types of Long-Distance Services

24 Regional and Metro Telecommunications

Defining Regional and Metro Telecommunications

Regional Distribution

Regional Telecommunications Networks

Metro Networks

Regional/Metro Services and Equipment

25 Local Telephone or "Access" Networks

Structure of the Local Phone Network

Subscriber and Access Services

Emerging Services and Competing Technologies

Fiber to the Home or Premises

26 Internet Access and Local-Area Networks

Data and Voice Transmission

The Internet and Its Structure

Data Transmission Technologies

Fiber Data-Link Design

Fiber in Standard Data Networks

27 Video Transmission

Video Basics

Transmission Media

Cable Television Architecture

HDTV and Cable

Other Video Applications

28 Mobile Fiber-Optic Communications

Mobile Systems

Remotely Controlled Robotic Vehicles

Fibers in Aircraft

Shipboard Fiber-Optic Networks

Automotive Fiber Optics

29 Fiber-Optic Sensors

Fiber-Sensing Concepts

Fiber-Optic Probes

Fiber-Sensing Mechanisms

Some Fiber Sensor Examples

Fiber-Optic Gyroscopes

Smart Skins and Structures

30 Imaging and Illuminating Fiber Optics

Basics of Fiber Bundles

Optics of Bundled Fibers

Imaging Applications

Light Piping and Illumination

Appendices

Appendix A: Important Constants, Units, Conversion Factors, and Equations

Appendix B: Decibels and Equivalents

Appendix C: Standard Time-Division Multiplexing Rates

Appendix D: ITU Frequencies and Wavelengths for L- and C-bands, 100-GHz Spacing, 100 Channels

Appendix E: Laser and Fiber Safety

Appendix F: Fiber-Optic Resources

Glossary

Index

Preface

About This Edition

Except for this preface, the front matter, and the errata that follows, this Laser Light Press edition reprints the fifth edition of Understanding Fiber Optics published in 2006 by Pearson Education, Inc. I am planning a sixth edition, but because that will take a while to prepare and with the Pearson edition is no longer available, I am reprinting the fifth through Laser Light Press. It may not cover the cutting edge of fiber optics, but it does cover the fundamentals you need to understand the field.

This edition also is an experiment. I want to see how reducing the book's price will affect sales and make Understanding Fiber Optics more accessible to students. Thus Laser Light Press offers a low-cost PDF electronic version and a relatively inexpensive print-on-demand paperback. The many diagrams make an e-reader version more difficult.

Whether you are an instructor, a student or a general reader, I would appreciate your comments and suggestions. If you are teaching a course based on the book, please contact me at jeff@jeffhecht.com for an instructor's manual. You can find more information on the book's status and on associated material at through http://www.understandingfiberoptics.com or through http://www.jeffhecht.com.

About Fiber Optics

Fiber optics has come a long way since I wrote the first edition of Understanding Fiber Optics in 1987. Optical-fiber communications was a radical new technology then, used mostly for high-capacity, long-distance transmission of telephone signals. I used a 1200-baud modem to send text messages from my computer through proprietary networks. Today a fiber-optic cable to my home provides a broadband connection to the Internet. A global network of fiber-optic cables links my phone and my computer to every continent except Antarctica, and a new cable is being laid through the Arctic Ocean.

Fiber optics has revolutionized telecommunications in the same way the railroads revolutionized land transportation in the years my great-great-grandfather worked for one. Like the railroad business, the fiber-optic business has had its spectacular booms and busts. The telecommunications bubble brought dreams of riches, but the bust that followed left nightmares of ruin and grim jokes about the stocks of once high-flying companies. Yet the bubble and its aftermath are reminders that fiber optics is a technology that may be too good for its own good. Like the railroads and the Internet, fiber optics was something so good that the stock market wildly overvalued it; and like the Internet, fiber optics will be part of our future.

I wrote the first edition of this book mainly for self-study, but it is now used widely in classroom settings. My goal is to explain principles rather than to detail procedures. When you finish, you should indeed understand fiber optics. You should be able to understand what the field is all about, comprehend what you read in trade journals such as Lightwave or Laser Focus World, make sense of what people in the field are saying, and explain fiber optics to your Aunt Millie or your niece. You won't be ready to design a brand new system, but you will be literate in the field. Think of it as Fiber Optics 101, a foundation for your understanding of a growing technology.

To explain the fundamentals of fiber optics, I start with ideas that may seem basic to some readers; the details will follow. To make concepts accessible, I include drawings to show how things work, limit math to simple algebra, and step through some simple calculation to show how they work. I compare fiber optics with other common technologies and highlight similarities and differences. I have organized the book to facilitate cross-referencing and review of concepts, and made a point of adding a thorough index to make its contents accessible. I also include some information on the business side of the technology, and boxes that talk about key issues that the fiber-optics community needs to think about.

The book introduces basic concepts first, then digs deeper into hardware and applications. The chapters are organized as follows:

      • The first three chapters are an introduction and overview. Chapter 1 tells how fiber optics are used and how the technology developed. Chapter 2 introduces optics, light, and the concept of light guiding. Chapter 3 introduces other basic concepts of communications and fiber-optic systems. They assume no background in optics or telecommunications.

      • 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 explain the fiber concepts used in the rest of the book. Chapter 7 covers special-purpose fibers used in optical amplifiers and fiber gratings, photonic-crystal or microstructured fibers, and planar waveguides. Chapter 8 is an overview of cabling.

      • Chapters 9 to 12 cover laser and LED light sources including diode and fiber lasers, 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 to 16 cover other components. Chapter 13 covers connectors and splices that join fibers. Chapter 14 covers optical couplers and other passive components in simple fiber systems and describes integrated optics. Chapter 15 covers optics that send signals at many separate wavelengths through the same fibers. Chapter 16 covers optical modulation and switching for optical networking.

      • Chapter 17 covers fundamentals of optical and fiber-optic measurements and explains the quirks of optical measurements. Chapter 18 describes fiber-optic testing.

       • Chapters 19 to 22 cover general principles of fiber communication. Chapter 19 describes fundamental concepts of fiber-optic systems and optical networking and how they work in practice. Chapter 20 describes communication standards. Chapter 21 outlines design of point-to-point single-wavelength systems, with sample calculations, so you can understand their operation. Chapter 22 describes the design of optical networks.

      • Chapters 23 to 27 explain 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 networks in cars, military systems, and aircraft.

      • The final two chapters describe non-communication applications. Chapter 29 explains the principles and operation of fiber-optic sensors. Chapter 30 covers imaging and illumination with fiber optics.

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

Appendices tabulate useful information, including values of important physical constants, conversion factors, and a few key formulas. They're all in one place to make them easier to find. They also include an annotated list of resources, in addition to the suggestions for further reading in each chapter. So many resources are available on the Internet that I can't hope to compile a thorough list; I encourage you to use search engines creatively. I welcome your comments, questions, and suggestions at jeff@jeffhecht.com.

Jeff Hecht

Auburndale, Massachusetts

March 2015