Overview

It is easy to argue that the general field of optics has enabled all of the successes of the fiber optics industry. Indeed, from a historical point of view, it is plain to see that the theory of guided waves of optical-wavelength signals has existed since Maxwell's time. The real breakthroughs came when new materials were introduced that made long distance propagation a reality. That development, along with high-performance lasers and erbium-doped fiber amplifiers, has introduced a whole new world of capability.

The rules in this chapter are intended to introduce some basic optics concepts for the designer who is new to optical systems. They may be most useful for engineers who are familiar with designing telephone and other "copper-based" systems that do not involve optics. While we were not able, in this small space, to cover all of the key topics that should be known to anyone working in fibers or optics in general, we have included some important topics.

Perhaps the most important is a rather large rule that describes the often-overlooked topic of etendue ^[*] (typically 10 ⁸ to 10 ⁵ cm ²-sr). Similarly, we provide some rules related to the properties of Gaussian beams, a field that is always useful when dealing with light emitted from lasers. Almost everyone encounters a situation now and then in which a quick model of the shape of a Gaussian beam is useful, so we have included one. Additional rules about Gaussian beams can be...