Presentation on optical fiber communination

1. SEMINAR AND TECHNIQAL WRITING
PRESENTATION ON
OPTICAL FIBER COMMUNICATION
MRIDULA GHOSH
ROLL NO: 519CR3001
DEPARTMENT OF CERAMIC ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
ROURKELA-769 008

2. BRIEF FLOW OF PRESENTATION
INTRODUCTION
WHAT ARE OPTICAL FIBERS?
HISTORYOFOPTICALFIBER
USESOFOPTICALFIBER
STRUCTURE OF OPTICAL FIBER
WORKING PRINCIPLE OF OPTICAL FIBER
OPTICAL FIBER COMMUNICATIONSYSTEM
ADVANTAGE /DISADVANTAGE OF OPTICALFIBER
APPLICATION OF OPTICALFIBER
CONCLUSION

3. WHAT IS OPTICAL FIBER ?
 An optical fiber is a flexible, transparent fiber made of high quality
glass (Silica) or plastic, slightly thicker than a human hair
 It either functions as a waveguide or light pipe that transmits light
between two ends of the fiber or fiber cable.
 Optical fibers are widely used in fiber-optic communications, which
permits transmission over longer distances and at higher bandwidths
(data rates) than other forms of communication
 Fibers are used instead of metal wires because signals travel along
them with less loss and are also safe to electromagnetic interference.
 The field of applied science and engineering concerned with the
design and application of optical fibers is known as fiber optics.

4. HISTORYOFFIBEROPTICS
Fiberoptics isnot reallya new technology, itsfairlyold
Guiding of light by refraction, the principle that makes fiber optics
possible,wasfirstdemonstrated by Daniel Colladon and jacques
babinet inparisin the early 1840s

5. STRUCTURE OF OPTICAL FIBER
 Core- central tube of very thin size made up of optically
transparent dielectric medium andcarries the light form
transmitter to receiver.The core diameter can vary from about
5um-100um.
 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.

6. UsesOfOpticalFiber
 Fiber optic can accommodate variety of needs.
 It can be used in communication, fiber optic sensors, illumination,
medical.
 And also in other places where bright light needs to be shone on a target
without a clear line-of-sight path.
 Used in building to route sunlight from the roof to other parts of the
building.
 And many more usages but we will only discuss use of optical fiber in
communication here.

7. INCOMMUNICATION …
 Optical fiber can be used as a medium for telecommunication
and computer 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 compared to electrical cables.
 The per-channel light signals propagating in the fiber have
been modulated at rates as high as 111 gigabits per second
(gbit/s) by ntt, although 10 or 40 gbit/s is typical.
 In june 2013, researchers demonstrated transmission of 400
gbit/s over a single channel.
 Each fiber can carry many independent channels, each using a
different wavelength of light
 As of 2011 the record for bandwidth on a single core was 101
tbit/sec (370 channels at 273 gbit/sec each).
 The record for a multi-core fibre as of january 2013 was 1.05
petabits per Second

8. WORKING PRINCIPLE
When an ray of light travels from a denser to a rarer medium such
that the angle of incidence is greater than the critical angle, the ray
reflects back into the same medium this phenomena is calledTIR.
In the optical fiber the rays undergo repeated total number of
reflections until it emerges out of the other end of the fiber, even if
fiber is bend.
TOTAL INTERNAL REFLECTION(TIR)

9. CLASSIFICATION OF OPTICAL FIBER
2) THE REFLECTIVE INDEX-
 Step index optical fiber
 Graded- index optical fiber
Optical fiber is classified into two categories based
on:-
1)THE NUMBER OF MODES-
 Single mode fiber(SMF) and
 Multi-mode fiber(MMF)

10. 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.

11. MULTI- MODE FIBER
 Allows a large number of modes for
Light ray travelling through it.
 The core diameter is 40um andthat of cladding
is 70um.
 The relative refractive index difference is
also large than single mode fiber.
 There is signal degradation dueto multimode
dispersion.
 It is not suitable for long distance
communication due to large dispersion and
attenuation of signal

12. ON THE BASIS OF REFRACTIVE INDEX
There are two type of opticalfiber:-
1) Step index optical fiber
2) Graded- index optical fiber

13. 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.

14. 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 givean
modulation of the light wavecarrier.
• Optical source- it provides the electrical-optical
conversion. It may be a semiconductor laser or an LED.

15. CONTINUED…
• 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 receivethe
information in the form of electrical signal.

16. Attenuation is the loss of the opticalpower.
Attenuation in optical fiber take place due to elementslike coupler, splices,
connector and fiber itself.
Attenuation

17. VARIATION OF SPECIFIC ATTENUATION WITH WAVELENGTH

18. ADVANTAGE OF OPTICAL FIBER
 Immense bandwidth to utilize
 Total electrical isolation in the transmission medium
 Very low transmission loss
 Small size and lightweight
 High signal security
 Very low power consumption and wide scopeof system expansion etc.

19. LOSS IN OPTICAL FIBER
Losses vary greatly depending upon the type of fiber
Plastic fiber may have losses of several hundred db per kilometer
Graded-index multimode glass fiber has a loss of about 2–4 db
Per kilometer
Single-mode fiber has a loss of 0.4 db/km or
Less

20. BENEFITS OF OPTICAL FIBER
 For short distance application, such as a network in an office building,
fiber- optic cabling can save space in cable ducts. This is because a single
fiber can carry much more data than electrical cables such as standard
category 5 ethernet cabling, which typically runs at 100 mbit/s or 1 gbit/s
speeds.
 Fiber is also immune to electrical interference; there is no cross-talk
between signals in different cables, and no pickup of environmental noise.
 Non-armored fiber cables do not conduct electricity, which makes fiber a
good solution for protecting communications equipment in high voltage
environments, such as power generation facilities, or metal
communication structures prone to lightning strikes.
 They can also be used in environments where explosive fumes are present,
without danger of ignition.

21. DISADVANTAGE
1) System installation is verycostly.
2) Only point-to-point communication ispossible.
3) Precise and costly instruments would berequired.
4) Splicing is time consuming.
5) It accept only unipolarcodes.

23. APPLICATIONS
Optical fiber have wider range ofapplication in
almost all field, some are specified below:-
In telecommunication field
Civil, consumer and industrial application
In military applications
Broadband applications
In decorations, etc.

24. 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.

25. THANK YOU…