pools of different types of optical fiber being shipped by cable manufacturers, you will easily understand why their stockmarket values appeared during the first half of the year 2000 to represent the liftoff of a Saturn-bound rocket. Similarly, the manufacturers of a variety of optical components such as lasers, light-emitting diodes (LEDs), couplers, optical modems, and multiplexers have been recognized as growth stocks as numerous organizations either acquire optical systems on a turnkey basis or pur- chase individual components and integrate those components into an optical system to satisfy their organizational requirements. One common measurement of optical deployment is given in terms of a communications carrier's installed or planned installation of fiber miles. Here the term fiber miles represents the length of the fiber con- duit installed or to be installed by a network operator multiplied by the illuminated (lit) and dark fiber-optic strands in the conduit. The term lit refers to those fibers that transport information, while the term dark rep- resents those strands not yet in use. Because a major cost associated with the construction of a fiber-optic network involves acquiring rights-of- way, digging a trench, and installing a conduit, adding dark fiber for later illumination is a common practice. Table 1.1 summarizes the net- work buildout of six communications carriers in terms of fiber miles. Although fiber miles represents an important indication of the scope of geographic coverage of a network, it does not indicate the true capacity of a network. Concerning network capacity, it is important to note the type of fiber installed, as certain types of fiber are more suitable than other types for supporting high-speed transmission at data rates of 10 Gbits/s (gigabits per second) and an emerging transmission rate of Gbits/s per strand of optical fiber, topics that will be covered in this book. Book Focus As readers have a diverse background and their organizations have differ- ent networking requireme