SEMINAR ON

FI BER-OPTICAL DATA TRANSMISSION

Presented by: QUAZI SADAFF REHAAN13MCA007

RAVENSHAW UNIVERSITY

Brief flow of presentation

1. Introduction2. Why Optical fibres?3. Evolution of optical fibre4. What is optical fibre?5. Structure of optical fibre6. Workings principle of optical fibre7. Classification of optical fibre8. Optical fibre communication system9. Advantages / Disadvantages of Optical

fibre10.Applications of Optical fibre11.Conclusion

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.

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)

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.

Structure of optical fibre

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.

Total internal reflection in optical fibre

Refraction

Refraction is the changing direction of light when it goes into a

material of different density

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.

Classification of optical fibre

• Optical fibre is classified into two categories based on :-

1) The number of modes, and2) The refractive index

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.

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.

On the basis of Refractive index

• There are two types of optical fibre:-

• (i) Step-index optical fibre• (ii) Graded-index optical fibre

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.

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.

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

Optical fibre Communication System

Information source

Electrical source Optical source Optical fibre

cable Optical

detector Electrical receive Destination

• 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.

• 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.

Advantage of optical fibre communication

1) The life of fibre is longer than copper wire2) 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.

•

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.

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.

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

• 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

Optical fibre in Sea

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

Optical fibres are playing a significant role in implementation of the ambitious “Digital India”

campaign by our hon’ble Prime Minister.

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.

THANK YOU

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