The following ppt gives overview about Optical Communication and the underlying principle with the general overview of all the contents for optical communication
2. Introduction
Optical Fiber Communication
Principle of Operation
Optical Fiber
Networking
Applications
Fiber Space Optic
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3. The light-guiding principle behind optical fibers was first demonstrated
by Daniel Colladon and Jaques Babinet
Optical fibers are widely used in fiber-optic communication, which
permits transmission over longer distances and at higher data rates
than other forms of wired and wireless communications.
Optical fibers are long, thin strands of very pure glass usually 120 µm
in diameter. They are arranged in bundles called optical cables and
used to transmit light signals over long distances.
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7. Propagation of light wave through Optical
fiber
Any light wave which travels along the core and meets the
cladding at the critical angle of incidence will be totally
internally reflected. Therefore light wave is propagated along
the fiber core by a series of total internal reflections.
8. Acceptance Angle
Meridional ray A enters the fiber core at an angle θa.
Incident ray b at an angle greater than θa is refracted into the
cladding an eventually lost by radiation.
An acceptance angle defined by the conical half angle θa. θa is the
maximum angle to the axis at which light may enter the fiber in
order to be propagated is called acceptance angle for the fiber.
9. Numerical Aperture (NA)
Numerical aperture of the fiber is the light collecting efficiency of
the fiber and is the measure of the amount of light rays that can be
accepted by the fiber. It is equal to the sine of acceptance.
NA = n0 sin θa = (n1
2
– n2
2
)1/2
where, n1 and n2 are the refractive indices of core and
cladding respectively.
Numerical aperture of step index fiber is given as
NA = n1 √2∆
11. Fiber Core Fiber Cladding
The core of a conventional
optical fiber is a cylinder of
glass or plastic that runs along
the fiber's length. The core is
surrounded by a medium with
a lower index of refraction,
typically a cladding of a
different glass, or plastic
Cladding is one or more
layers of materials of lower
refractive index, in intimate
contact with a core material of
higher refractive index. The
cladding causes light to be
confined to the core of the
fiber by total internal reflection
at the boundary between the
two.
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13. In practical fibers, the cladding is usually coated with a tough resin buffer
layer
Buffer layer be further surrounded by a jacket layer, usually plastic
These layers add strength to the fiber but do not contribute to its optical
wave guide properties.
Rigid fiber assemblies sometimes put light-absorbing ("dark") glass between
the fibers, to prevent light that leaks out of one fiber from entering another.
This reduces cross-talk between the fibers
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15. Fiber Types
Classification on the basis of the refractive index of the material
Step index fiber
Refractive index of core is uniform throughout and
undergoes an abrupt change at the core cladding
boundary.
16. In the graded index fiber, the refractive index of the core
is made to vary in the parabolic manner such that the
maximum value of refractive index is at the center of the
core.
17. Based on the modes propagating in optical fiber:
Single mode fiber
Multi mode fiber
Single mode fiber
Single mode fiber optic cable has a small diametric core that allows
only one mode of light to propagate.
Multi mode fiber
Multimode fiber optic cable has a large diametric core that allows
multiple modes of light to propagate
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18.
19. Comparison
Single mode fiber Multi mode fiber
► Core radius is small.
► Supports one mode of propagation.
► Optical source- LASER.
► The launching of optical power into
fiber is difficult as the core radius is
small.
► Supports larger bandwidth.
► Intermodal dispersion is absent.
► Used for long distance
communication.
► Core radius is large.
► Supports hundreds of modes.
► Optical source- LED.
► The launching of optical power into
fiber is easier as the core radius is
large.
► Supports lesser bandwidth.
► These fiber suffer from Intermodal
dispersion.
► Used for short distance
communication.
21. Optical fibers are connected to terminal
equipment by optical fiber connectors
Optical fibers may be connected to each other
by connectors or by splicing
that is, joining two fibers together to form a
continuous optical waveguide
For quicker fastening jobs, a "mechanical
splice" is used
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22. Splicing is the method to connect one fiber optic cable to
another permanently. Splices are "permanent"
connections between two fibers.
It is the attribute of permanence that distinguishes a
splice from connectors.
Splicing is only needed if the cable runs are too long for
one straight pull or you need to mix a number of different
types of cables.
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23. An optical network unit (ONU) is a device that
transforms incoming optical signals into electronics at a
customer's premises in order to
provide telecommunications services over an optical
fiber network.
ONU provides the subscribers with broadband Internet
access.
It is used in combination with an optical line
terminal (OLT).
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24. Fiber optic couplers are used to split the input signals
into two or more outputs; they are called splitters in this
case.
On the other hand, some types of couplers can be used
to combine two or more inputs into one single output;
they are called combiners in this case.
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26. Optical fiber communication
Optical fiber can be used as a medium for telecommunication and
networking because it is flexible and can be bundled as cables.
It is especially advantageous for long-distance communications,
because light propagates through the fiber with little attenuation
This allows long distances to be spanned with few repeaters.
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27. Fiber optic sensors
Optical fibers can be used as sensors to measure strain,
temperature, pressure and other parameters.
The small size and the fact that no electrical power is
needed at the remote location gives the fiber optic
sensor advantages to conventional electrical sensor in
certain applications.
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28. Other uses of optical fibers
• Fibers are widely used in
illumination applications.
• They are used as light guides in
medical and other applications In
some buildings
• optical fibers are used to route
sunlight from the roof to other parts
of the building
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A frisbee illuminated by fiber optics
30. FSO was initially developed by NASA and US Military.
FSO is a line of sight technology which uses LASERS
and photo-detectors to provide optical connection
between two point without using optical fibers.
Uses invisible beam of light to provide optical bandwidth
connections.
FSO can transmit video ,data etc. at high speed capable
of reaching a speed of 1.25Gbps
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31. It's based on connectivity between FSO-based
optical wireless units.
Provide full-duplex (bi-directional) capability.
Each optical wireless unit uses an optical source,
plus a lens or telescope.
Receiving lens or telescope connects to a high-
sensitivity receiver via optical fiber.
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33. Advantages Disadvantages
Ultra High Bandwidth
Small size & weight
Electrical Isolation
Immune to electrical
Interference
Signal security
Low transmission loss
Ruggedness , flexibility
Point to Point
Communication
High maintenance cost
Expensive optical
transmitter & receiver
Prone to corrosion
Difficult to splice compare
to wires
High optical power may
result in fiber fuse
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