DENAMSE ANGONO DERKOS TIREL
ID: 004-520
OPTICAL COMMUNITION SYSTEMS (OCS)
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Introduction to Optical Communication Systems
Parts of Optical fiber
Working Principle of Optic Fiber
Optical Sources (LED or Lasers )
Type of Optic Fiber
Basic elements Optical Communication
Applications of Optic fibers
Advantages and Disadvantages of Optical Fiber
Conclusion
References
Optical communication systems use light to transmit
information from one place to another.
Light is a type of electromagnetic radiation like radio
waves. Today, infrared light is being used
increasingly as the carrier for information in a
communication system. The transmission medium is
either free space or a special light-carrying cable
called a fiber-optic cable. Because the frequency of
light is extremely high, it can accommodate very high
rates of data transmission with excellent reliability.
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Core made of high quality silica glass or plastic
Cladding made of high quality silica glass or
plastic, with a lower refractive index than the core
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Reducing scattering losses
Adds mechanical strength to the fiber
Protects the core from absorbing unwanted surface
contaminants
Protective outer covering called buffer
Depending upon the material composition of the core, there are
two types of fibers used commonly. They are:
Step-index fiber: The refractive index of the core is uniform
throughout and undergoes an abrupt change (or step) at the
cladding boundary.
Graded-index fiber: The core refractive index is made to vary
as a function of the radial distance from the center of the fiber.
Both of these are further divided into:
Single-mode fiber: These are excited with laser.
Multi-mode fiber: These are excited with LED.
The major elements of an optical fiber communication
system are shown in the following figure.
The basic components are light signal transmitter,
the optical fiber, and the photo detecting receiver.
The additional elements such as fiber and cable
splicer and connectors, regenerators, beam
splitters, and optical amplifiers are employed to
improve the performance of the communication
system.
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Communications / Data Storage
Military Applications
Medical Systems
Mechanical or Industrial
Networking
Broadcast (TV cabling)
Lighting and Imaging
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High bandwidth
Safety and security
High speed
Immune to electromagnetic interference
Suitable for industrial and noisy areas
Signals carrying data can travel long distances
without weakening
Light weight and small diameter
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Optical fibre cables are expensive
Sophisticated technology required for installing,
manufacturing and maintaining optical fibre cables
cost is high
Light waves are unidirectional, so two frequencies
are required for full duplex transmission
The numbers of repeaters are to be increased with
distance.
They are fragile if not enclosed in a plastic sheath.
Hence, more protection is needed than copper ones
With the introduction of highly transparent fiber-optic
cable in the 1970s, very high-frequency laser signals now
carry phenomenal loads of telephone conversations and
data across the country and around the world.
From surgical procedures to worldwide communication via
the internet, fiber optic has revolutionized our world. Fiber
optics has made important contributions to the medical
field, especially with regards to surgery. One of the most
useful characteristics of optical fibers is their ability to
enter the minute passageways and hard-to-reach areas of
the human body. But perhaps the greatest contribution of
the 20th century is the combination of fiber optics and
electronics to transformed telecommunications.
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http://library.thinkquest.org/TQ0312432/lessons_part-04.html
http://www.greatachievements.org/?id=3706
Telecom book: jyrki-t-j-penttinenthe-telecommunicationshandbook-engineering -guidelinespdfzzzzz.pdf