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An Entry-Level Guide

Fourth Edition

Copyright © 2019 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

Published simultaneously in Canada.

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To my many friends in the optics community, to the many people who have given graciously of their time helping me understand more about optics, people, and the world around us, and to the coming generation in hope this book helps you get started in the fascinating world of lasers and optics.

“For Credible Lasers, See Inside.”

The laser is less than three years younger than the space age. Just days after the Soviet Union launched Sputnik I on October 4, 1957, Charles Townes and Gordon Gould had two crucial discussions at Columbia University about the idea that would become the laser. As the United States and Soviets launched the space race, Townes and Gould went their separate ways and started their own race to make the laser. On May 16, 1960, Theodore Maiman crossed the laser finish line, demonstrating the world’s first laser at Hughes Research Laboratories in California.

Bright, coherent, and tightly focused, laser beams were a new kind of light that excited the imagination. Science fiction writers turned their fictional ray guns into lasers with a stroke of the pen. Science writers inhaled deeply of the technological optimism of the early 1960s and wrote breathless predictions about the future of “the incredible laser.” An article in the November 11, 1962, issue of the Sunday newspaper supplement This Week revealed U.S. Army schemes for equipping soldiers with a “death-ray gun … small enough to be carried or worn as a side-arm.” It quoted Air Force Chief of Staff Curtis E. LeMay predicting that ground-based lasers could zap incoming missiles at the speed of light.

The reality was something else. A bemused Arthur Schawlow, who had worked with Townes on the laser, posted a copy of “The Incredible Laser” on his door at Stanford University, along with a note that read, “For credible lasers, see inside.” Irnee D’Haenens, who had helped Maiman make the first laser, called the laser “a solution looking for a problem,” a joke that summed up the real situation and became a catchphrase for the young laser industry. The infant laser had tremendous potential, but it had to grow up first.

D’Haenens’s joke lasted many years. So did the popular misconception that lasers were science-fictional weapons. If you told your neighbors you worked with lasers in the 1970s, they inevitably thought you were building death rays. That began to change as supermarkets installed laser scanners to automate checkout in the early 1980s. Then lasers began playing music on compact disks. Laser printers, laser pointers, CD-ROMs, and DVD players followed. Laser surgery became common, particularly to treat eye disease. Surveyors, farmers, and construction workers used lasers to draw straight lines in their work. Lasers marked serial numbers on products, drilled holes in baby-bottle nipples, and performed a thousand obscure tasks in the industry. Lasers transmitted billions of bits per second through optical fibers, becoming the backbone of the global telecommunications network and the internet.

The incredible laser has become credible, a global business with annual sales in the billions of dollars. Lasers have spread throughout science, medicine, and industry. Laser-generated digital signals are the heavy traffic on the fiber-optic backbone of the global information network. Lasers are essential components in home electronics, buried inside today’s CD, DVD, and Blu-Ray players. Laser pointers are so cheap that they are cat toys. It is a rare household that does not own at least one laser, though most are hidden inside electronics or other things. Yet, lasers have not become merely routine; they still play vital roles in Nobel-grade scientific research.

This book will tell you about these real-world lasers. To borrow Schawlow’s line, “For credible lasers, see inside.” It will tell you how lasers work, what they do, and how they are used. It is arranged somewhat like a textbook, but you can read it on your own to learn about the field. Each chapter starts by stating what it will cover, ends by reviewing key points, and is followed by a short multiple-choice quiz.

We start with a broad overview of lasers. Chapter 2 reviews key concepts of physics and optics that are essential to understand lasers. You should review this even if you have a background in physics, especially to check basic optical concepts and terms. Chapters 3 and 4 describe what makes a laser work and how lasers operate. Chapter 5 describes the optical accessories used with lasers. Try to master each of these chapters before going on to the next.

Chapters 6 to 11 describe various types of lasers. Chapter 6 gives an overview of laser types and configurations and explains such critical concepts as the difference between laser oscillation and amplification, the importance of laser gain, and tunable lasers. Chapter 7 describes the workings of gas lasers and important types such as the helium-neon and carbon dioxide lasers. Chapter 8 covers solid-state lasers, from tiny green laser pointers to giant laboratory systems. Chapter 9 covers fiber lasers, the fastest-growing solid-state laser, now widely used in the industry because of its power and high efficiency, along with fiber amplifiers used in telecommunications. Chapter 10 covers the hot area of semiconductor diode lasers, ranging from tiny chips to powerful pumps for other lasers. Chapter 11 describes other types of lasers, including tunable dye lasers, extreme ultraviolet sources, and free-electron lasers.

The final three chapters cover laser applications, divided into three groups. Chapter 12 describes low-power applications, including communications, measurement, and optical data storage. Chapter 13 covers high-power applications, including surgery, industrial materials processing, and laser weapons. Chapter 14 focuses on research and emerging developments in areas including spectroscopy, slow light, laser cooling, and extremely precise measurements. The appendices, glossary, and index are included to help make this book a useful reference.

To keep this book to a reasonable length, we concentrate on lasers and their workings. We cover optics and laser applications only in brief, but after reading this book, you may want to study them in more detail.

I met my first laser in college and have been writing about laser technology since 1974. I have found it fascinating, and I hope you will, too.

JEFF HECHT

Auburndale, Massachusetts