Presented at- Department of MCA, Ravenshaw University, Cuttack

2. Brief flow of presentation
1. Introduction
2. Why Optical fibres?
3. Evolution of optical fibre
4. What is optical fibre?
5. Structure of optical fibre
6. Workings principle of optical fibre
7. Classification of optical fibre
8. Optical fibre communication system
9. Advantages / Disadvantages of Optical fibre
10. Applications of Optical fibre
11. Conclusion

3. Why optical fibres??
1
• A single optical fibre can carry up to 30,00,000 full duplex
voice calls or 90,000 TV channels.
2
• fibre optics is offering speed at 100Mbps as compared to
24Mbps limit over DSL network in India.
3
• Speed up to 32 Tbps has been achieved by researchers. That
will roughly mean an entire 1 Gb movie transfer in 0.03
millisecs.

4. Evolution of optical fibre
• 1880 – Alexander Graham Bell & Sumner Tainter
• 1940 – Daniel Colladon & Jaques Babinet
• 1965-German physicist Manfred Borner
• Charles K Kao & George A Hockham
First ocean spanning 13000 Km fibre optic cable called TAT-
8 extended from Tuckerton,New Jersey to
Widemouth(England) and Penmorch(France)

5. What is optical fibre?
• An optical fibre is a hair thin cylindrical fibre of glass
or any transparent dielectric medium.
• The fibre which are used for optical communication
are wave guides made of transparent dielectrics.
• Its function is to guide visible and infrared light over
long distances.

6. Structure of optical fibre

7. Working principle
Total Internal Reflection
• When a 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 called total internal reflection.
• In the optical fibre the rays undergo repeated total
number of reflections until it emerges out of the other end
of the fibre, even if the fibre is bent.

8. Total internal reflection in
optical fibre

9. Refraction
Refraction is the changing direction of light when it goes
into a material of different density

10. Attenuation
• Attenuation is the loss of the optical power.
• Attenuation in optical fibre take place due to elements
like coupler, splices, connector and fibre itself.
• A fibre with lower attenuation will allow more power
to reach a receiver than with a higher attenuation.

11. Classification of optical fibre
• Optical fibre is classified into two categories based on
:-
1) The number of modes, and
2) The refractive index

12. On the basis of number of modes:-
on the basis of number of modes of propagation the optical fibre are
classified into two types:
(i) Single mode fibre (SMF) and
(ii) Multi-mode fibre (MMF)
• Single-mode fibres – in single mode fibre only one mode can propagate
through the fibre. This type of fibre has small core diameter(5um)
and high cladding diameter(70um) and the difference between the
refractive index of core and cladding is very small. There is no
dispersion i.e. no degradation of signal during travelling through the
fibre.
• The light is passed through the single mode fibre through laser diode.

13. Multi-mode fibre :-
• Multi mode fibre allows a large number of modes for the
light ray travelling through it.
• The core diameter is (40um) and that of cladding is(70um)
• The relative refractive index difference is also larger than
single mode fibre.
• There is signal degradation due to multimode dispersion.
• They are not suitable for long distance communication due to
large dispersion and attenuation of the signal.

14. On the basis of Refractive index
• There are two types of optical fibre:-
• (i) Step-index optical fibre
• (ii) Graded-index optical fibre

15. Step index fibre
• The refractive index of core is constant
• The refractive index of cladding is also constant
• The light rays propagate through it in the form of
meridiognal rays which cross the fibre axis during every
reflection at the core cladding boundary.

16. Graded Index fibre
• In this type of fibre core has a non uniform refractive index
that gradually decrease from the centre towards the core
cladding interface.
• The cladding has a uniform refractive index.
• The light rays propagate through it in the form of skew rays
or helical rays. They do not cross the fibre axis at any time.

18. How Optical fibres are made??
• Three Steps are Involved in the manufacturing of the
optical fibre which are given below:-
-Making a Preform Glass Cylinder
-Drawing the fibres from the preform
-Testing the fibre

19. Optical fibre Communication System
Information
source
Electrical
source Optical source
Optical fibre
cable
Optical
detector
Electrical
receive Destination

20. • Information source- It provides 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 by pulse code modulation . It may be a
semiconductor laser or an LED.

21. • Optical cable: It serves as transmission medium.
• Optical detector: It is responsible for optical to
electrical conversion of data and hence responsible for
demodulation of the optical carrier.
• 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 desired form.

23. Advantage of optical fibre
communication
1) The life of fibre is longer than copper wire
2) Handling and installation costs of optical fibre is very nominal.
3) It is unaffected with electromagnetic interference .
4) Attenuation in optical fibre is lower than coaxial cable or twisted
pair.
5) There is no necessity of additional equipment for protecting
against grounding and voltage problems.
6) As it does not radiates energy any antenna or detector cannot
detects it hence provides signal security.

24. 1.A small optical fibre can carry more data than a bunch copper cables.
2.OF lags behind copper only in the aspects that copper is less expensive and
already deployed thanks to television and telephone network.
It is a unidirectional technology.

25. Disadvantage
1) Highly skilled staff would be required for
maintenance
2) Only point to point working is possible on optical
fibre
3) Precise and costly instruments would be required
4) Costly if under utilized.
5) Accept unipolar codes only.
6) Jointing of fibre and splicing is also time consuming.

26. Applications
• In telecommunication field
• In space applications
• Broadband applications
• Computer applications industrial applications
• Mining applications
• In medical applications
• In military applications etc.
Optical fibre have wider range of application in almost all
field, some are been specified below

27. • Optical fibre have wider range of application in almost all field, i.e. in medical,
electronics, military etc .some are been specified below
• Medical
• Military
• Electronics
IBM microprocessors

28. Optical fibre in Sea

29. The Endoscope
There are two optical fibres
One for light, to illuminate the
inside of the patient
One for a camera to send the
images back to the doctor. Key hole surgery

31. Optical fibres are playing a significant role in implementation of the
ambitious “Digital India” campaign by our hon’ble Prime Minister.

32. Conclusion
This concludes my presentation of fibre optical data
transmission. We have looked at how they work and what they are
made of . We have gone through some properties of optical fibres.
Although this presentation does not cover all the aspects of fibre-
optics and optical fibres,still I hope I have been able to give you a
glinse of this remarkable technology.