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1.2 | |
Networking Media | |
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Optical fiber |
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Fiber-optic cable is a networking medium that uses modulated light
transmissions. It can be costlier than other networking media,
depending on the purity and the size of the fiber used. The connectors
that terminate fiber also tend to be more expensive. Fiber is not
susceptible to electromagnetic or radio frequency interference. It is
capable of higher data rates than any of the other types of current
networking media. As the diameter of the fiber gets smaller, the
maximum transmission rate increases.
Data for fiber-optic cable are converted into pulses of light and this light is allowed to propagate down the fiber. As illustrated in Figure
Fiber-optic communication is rooted in a number of inventions made in the 19th century. It was not until the 1960s, when solid-state laser light sources and high-quality impurity-free glasses were introduced, that fiber-optic communication became practical. Telephone companies, who saw its benefits for long-distance communication, pioneered its use on a widespread basis.
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the light-guiding parts of an optical fiber are referred to as the
core and the cladding. The core is usually very pure glass with a
lower
index of refraction. When a cladding layer of glass or plastic with a
low index of refraction surrounds the core glass, light can be trapped
in the fiber core. This process is called total internal reflection,
and it allows the optical fiber to act like a light pipe that guides
light for tremendous distances, even around bends.