Overview

Revolutions in optics are infrequent but, in the case of lasers and laser diodes, the impact was immediate and profound. Although it took the conjunction of the invention of many complementary technologies [lasers, fibers, detectors, erbium-doped fiber amplifiers (EDFAs), and so forth] to make large optical telecom networks possible, much of the success depends on the ability to cheaply and efficiently create the transmitters that generate and repeat the modulated beams of light that carry information.

In addition to enabling communication systems, lasers have found their way into every home, most cars, and even people's pockets. For the more experienced (older) designer, it is astonishing to think that, just a few decades ago, lasers were expensive, huge, and hard to align. More important, the wide use of lasers has meant that experience with them can be transferred to the fiber community, the free-space communications community, and so on. In fact, much of the theory for both applications has been around for years and is the emphasis of this chapter.

Not surprisingly, the rules covered in this chapter concentrate on the ability of particular devices to create light for communication systems and methods for coupling that light into fibers. It also includes information on the noise properties of various types of lasers, including the currently popular EDFA systems. EDFA gets attention throughout the chapter because of its profound impact on fiber system design. To be complete, we have included a couple of rules related to the temperature sensitivity of EDFAs...