Understanding Lasers

An Entry-Level Guide

Jeff Hecht

• Publisher: Wiley-IEEE Press
• Year: 2018
• ISBN:
  9781119310662
• Edition: 4
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

The expanded fourth edition of the book that offers an essential introduction to laser technology and the newest developments in the field

The revised and updated fourth edition of Understanding Lasers offers an essential guide and introduction that explores how lasers work, what they do, and how they are applied in the real world. The author—a Fellow of The Optical Society—reviews the key concepts of physics and optics that are essential for understanding lasers and explains how lasers operate. The book also contains information on the optical accessories used with lasers.

Written in non-technical terms, the book gives an overview of the wide-variety laser types and configurations. Understanding Lasers covers fiber, solid-state, excimer, helium-neon, carbon dioxide, free-electron lasers, and more. In addition, the book also explains concepts such as the difference between laser oscillation and amplification, the importance of laser gain, and tunable lasers. The updated fourth edition highlights the most recent research and development in the field. This important resource:

• Includes a new chapter on fiber lasers and amplifiers
• Reviews new topics on physics of optical fibers and fiber lasers, disk lasers, and Ytterbium lasers
• Contains new sections on Laser Geometry and Implications, Diode Laser Structures, Optimal Parametric Sources, and 3D Printing and Additive Manufacturing
• Puts the focus on research and emerging developments in areas such as spectroscopy, slow light, laser cooling, and extremely precise measurements
• Contains appendices, glossary, and index that help make this book a useful reference

Written for engineering and physics students, engineers, scientists, and technicians, the fourth edition of Understanding Lasers contains the basic concepts of lasers and the most recent advances in the technology.

CHAPTER 1
Introduction and Overview

About This Chapter

This chapter will introduce you to lasers. It will give you a basic idea of their use, their operation, and their important properties. This basic understanding will serve as a foundation for the more detailed descriptions of lasers and their operation in later chapters. After a brief introduction to lasers, this chapter will introduce important laser properties and applications.

1.1 LASERS, OPTICS, AND PHOTONICS

To understand lasers, you should first understand where lasers fit into the broader science and technology of light. That field was long called optics, but now part of it is sometimes called photonics. The differences in the meanings of the two words reflect how the field has changed since the mid-20th century, and understanding those differences will help you understand both lasers and the larger world of light, optics and photonics.

Optics dates back to the origin of lenses in ancient times. It is the science of telescopes, spectacles, microscopes, binoculars, and other optical instruments that manipulate light using lenses, mirrors, prisms, and other transparent and reflective objects. Isaac Newton famously described the fundamentals of optics in his 1704 book Opticks. He thought light was made of tiny particles, but a century later an experiment by Thomas Young indicated light was made of waves, and opinion shifted for a while.

In the late 19th century, physicists discovered that light was a type of electromagnetic radiation, along with radio, infrared, ultraviolet, X-rays, and gamma rays. They differ in the lengths of the waves and in how fast they oscillate. The wavelength and frequency depend on each other because electromagnetic waves always travel at the speed of light. In the early 20th century, Albert Einstein showed that electromagnetic radiation could behave both as particles—called photons—and as waves, depending on how you looked at them. The only fundamental difference among electromagnetic waves was their wavelength, which could also be measured as frequency or (photon) energy.

The science and technology of light have also grown increasingly connected with electronics in the past century. Electronic devices can measure light by converting it into electronic signals and measuring them. Television cameras and displays include both optics and electronics. The first electronic circuits used vacuum tubes, but semiconductor devices began replacing tubes in the mid-20th century. That brought a new generation of electro-optic devices, including semiconductor electronics that emitted and detected light, converting signals and energy back and forth between photons and electrons.

In the late 20th century, the word photonics was coined to describe devices that manipulate photons, like electronics manipulate electrons. The use of the new term became controversial because many people who worked in optics in the field saw it as an attempt to “rebrand” their profession. Photonics has come to refer to things that manipulate light when it acts more like a particle (a photon) than a wave. By that definition, a laser or a sensor that converts light (a series of photons) into an electronic signal is considered photonics, but a lens that refracts and focuses light waves is considered optics. However, that definition remains somewhat hazy. Today, both terms are used, but at this writing, Google tells us that optics remains far ahead, indexed on 622 million web pages, compared to a mere 17.6 million for photonics.

Whatever you want to call the field, you should learn the physical basics of light, optics and photonics, to understand how lasers work. Chapter 2 will go into more detail.

1.2 UNDERSTANDING THE LASER

The laser was born in 1960, long before the word “photonics” came into use. Lasers retain a youthful image, thanks largely to continuing advances in the technology. They vary widely. Some lasers are tremendously sophisticated and incredibly precise scientific instruments costing tens or hundreds of thousands of dollars. Others are tiny semiconductor chips hidden inside optical disk players or pen-shaped red pointers used as cat toys. The world's biggest laser, the National Ignition Facility at the Lawrence Livermore National Laboratory, cost over a billion dollars and fills an entire building. The tiny lasers inside CD or DVD players are the size of grains of sand and cost pennies apiece. Red laser pointers sell for only a few dollars and are often given away.

We now take many laser applications for granted. For decades, laser scanners at store checkouts have read bar codes printed on packages to tally prices and manage their inventory. Laser ...