Fibre Optic Systems

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Presented by Sandeep Singh
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Brief flow of presentation

• Introduction
• What are Optical Fibers ?
• Structure of optical fiber
• Working principle of optical fiber
• Optical fiber communication system
• Advantage / Disadvantage of optical fiber
• Application of optical fiber
• Conclusion

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What is Optical Fiber ?
? An optical fiber is a hair thin cylindrical
fiber of glass or any transparent dielectric
medium.

• The fiber which are used for optical
  communication are wave guides made of
  transparent dielectrics.
• Its function is to guide visible and infrared
  light over long distance.

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Structure of optical fiber
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Conti

• Core- central tube of very thin size made up of
  optically transparent dielectric medium and
  carries the light form transmitter to receiver.
  The core diameter can vary from about 5um-100
  um.
• Cladding- outer optical material surrounding the
  core having reflecting index lower than core. It
  helps to keep the light within the core
  throughout the phenomena of total internal
  reflection.
• Buffer Coating- plastic coating that protects the
  fiber made of silicon rubber. The typical
  diameter of fiber after coating is 250-300um.

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Classification of optical fiber

• Optical fiber is classified into two categories
  based on-
• The number of modes-
• Single mode fiber(SMF) and
• Multi-mode fiber(MMF)

• 2) The reflective index-
• Step index optical fiber
• Graded- index optical fiber

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On basis of number of modes-
Single mode fiber-

• In single mode fiber only one mode can propagate
  through the
• fiber.
• It has small core diameter (5um) and high
  cladding diameter (70um).
• Difference between the refractive index of core
  and cladding is
• very small.
• There is neither dispersion nor degradation
  therefore it is suitable for long distance
  communication.
• The light is passed through the single mode fiber
  through laser diode.

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Multi- mode fiber

• It allows a large number of modes for
• light ray travelling through it.
• The core diameter is 40um and that of cladding
  is 70um.
• The relative refractive index difference is also
  large than single mode fiber.
• There is signal degradation due to multimode
  dispersion.
• It is not suitable for long distance
  communication due to large dispersion and
  attenuation of signal.

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On the basis of refractive index

• ? There are two type of optical fiber-
• Step index optical fiber
• Graded- index optical fiber

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Single Index fiber-

• Step-index optical fiber-the refractive index of
  core and cladding are constant.
• The light ray propagate through it in the form of
  meridiognal rays which cross the fiber axis
  during every reflection at the core cladding
  boundary.
• Graded Index Fiber-
• In this type of fiber core has a non uniform
  refractive index that gradually decrease from
  the center towards the core cladding interface.
• The cladding has a uniform refractive index.
• The light rays propagate through it in the form
  of helical rays. They never cross the fiber axis.

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Optical Fiber Communication System

• Information source- it provide an electrical
  signal to a transmitter comprising an electrical
  stage.
• Electrical transmitter- It drives an optical
  source to give an
• modulation of the light wave carrier.
• Optical source- It provides the
  electrical-optical conversion. It may be a
  semiconductor laser or an LED.

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Continue..

• Optical cable- It serve as transmission medium.
• Optical detector- It is responsible for optical
  to electrical conversion of data. It may be a
  photodiodes, phototransistors or
  photoconductors.
• Electrical receiver It is used for electrical
  interfacing at the receiver end of the optical
  link and to perform the signal processing
  electrically.
• Destination It is the final point at which we
  receive the information in the form of
  electrical signal.

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Advantage of Optical Fiber

• Immense bandwidth to utilize
• Total electrical isolation in the transmission
  medium
• Very low transmission loss
• Small size and light weight
• High signal security
• Very low power consumption and wide scope of
  system expansion etc.

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Conclusion
At the last, there are some negatives of using
optical fiber communication system in terms of
splicing, coupling, set up expenses etc. but it
is an un avoidable fact that optical fiber has
revolutionized the field of communication. As
soon as computers will be capable of processing
optical signals, the total arena of
communication will be opticalized immediately.
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Contact us
Address 25 Gilbert Park Drive, Knoxfield,
Victoria 3180 Australia Phone no. -61435390490
61 478716543
61 399001936
Website https//www.fibreoptic.com.au/
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Thank you..