Optical Fibers Optical Fibers are glass fibers usually about 120 micrometers in
diameter that are used to deliver wave signals in the form of pulses
of light over distances up to 50 km without the using repeaters. These
wave signals may be coded voice communications or computer data.
Fiber optic communications is dependent on the principle that light in
a glass medium can carry more information over longer distances than
electrical signals can carry in a copper or coaxial medium. The purity
of today's glass fiber mixed with advance electronics system allows
fiber to transmit digitized light signals well beyond 100 km without
amplification. Optical fiber is an ideal transmission medium with few
transmission losses, low interference and high bandwidth potential.
How Fiber Works
The working of an optical fiber is dependent on the principle of total
internal reflection. Light reflects or refracts based on the angle at
which it strikes a surface. This principle is at the center of how
optical fiber works. Restricting the angle at which the light waves
are delivered makes it possible to control how efficiently they reach
their destination. Light waves are covered with the core of the
optical fiber in much the same way that radio frequency signals are
covered with coaxial cable. The light waves are directed to the other
end of the fiber by being reflected within the core.
The creation of the cladding glass relative to the core glass decides
the fiber's capability to reflect light. That reflection is usually
occurred by creating a higher refractive index in the core of the
glass than in the surrounding cladding glass creating a "waveguide".
The refractive index of the core is improved by slightly changing the
composition of the core glass generally by adding small amounts of a
dopant. Alternatively the waveguide can be composed by decreasing the
refractive index of the cladding using different dopants.
Design of Fiber
Core, Cladding, and Coating
An optical fiber is made up of two different types of highly pure,
solid glass composed to form the core and cladding. A protective
coating surrounded with the cladding. In most cases the protective
coating is a double layer composition.
In the manufacturing process, a protective coating is applied to the
glass fiber as the final step. This coating protects the glass from
scratches and dust that can affect fiber strength. This protective
coating can be composed with two layers: a soft inner layer that act
as cushions to the fiber and permits the coating to be uncovered from
the glass mechanically and a harder outer layer that protects the
fiber during handling particularly the cabling, installation, and