This chapter initially presents the basic physical parameters that describe wave and signal propagation. The different media that support propagation have different characteristics and information capacities. The one of most concern for optical fiber systems is the index of refraction. Refraction refers to the bending of a propagating wave at a boundary. The refractive index of a media also determines the speed of propagation of the wave in the media. Section 1-3 discusses the three basic elements of any optical fiber system in very broad terms. Subsequent chapters give much more detail about the three.

Attenuation and dispersion, have been a concern since the beginning of optical fiber use. Polarization performance has become a concern as digital signaling speeds on fibers have progressed beyond 2.5 Gb/s. In designing optical fiber systems, end-to-end performance is generally governed by one or the other of the first two degradations, but generally not both at the same time. Polarization degradations become an added source of distortion for high-speed systems. In this chapter, silica fiber attenuation is discussed first in Section 3.2. The two main types of silica fiber, multimode and single-mode, do not differ greatly in attenuation. Section 3.3 discusses the wavelength dependent dispersion of silica fibers. This results in a time spread at the receiver. Multimode and single-mode fibers differ markedly in dispersion performance. This difference determines their two distinct areas of application: local networking, and long haul. Section 3.4 discusses the polarization performance of silica fibers. Finally, Section 3.5 presents information on the performance of non-silica fibers.

A signal undergoes an E/O transformation at a fiber optic transmitter and a corresponding O/E transformation at the receiver. This chapter discusses the O/E process, with emphasis on the first two blocks in that flow: the semiconductor optical detector, or photodiode, and preamplifier. The two together are referred to as the receiver's front-end. With the growing need for commercial systems operating at 10 and even 40 Gb/s, the design of front-ends has become more important and technically challenging.

Optical fibers provide the ability to use optics instead of metallic media to achieve numerous useful end results. In all cases the fiber requires an optical source and detector and cannot be used alone. As a result, optical fiber applications must always be considered in combination with their required E/O and O/E converters. This chapter looks at modern optical fiber telecommunications systems and the relationships between the source, fiber, and detector.