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Submitted to:-

Mrs. Sharmistha De Dutta

(Humanities Department)

Submitted by:-

Amit Kumar (095055)Ashish Kumar (095053)Aakash Kumar (095051)Mayank (095063)Vikash Kumar Singh (095054)Braja Gopal Bera (095060)

Under the guidance of

Mrs.Moutusi Mondal Roy

Deptt. :- E.C.E.(II)

Date:- 31ST

MARCH 2011

A

PROJECT ON

FIBRE OPTICS


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PREFACE

Fibre optics is a relatively new field which is still in the process of emerging asa full-fledged technology. The development in this is indeed breath taking with

major optical fibre industries fanning its growth through their R&D efforts.

However, the locomotives of its enormous growth during the last couple of

decade has essentially been the initiative taken by the private fibre industries

which could perceive correctly the enormous growth potential it offers for

increased and improved in this services to their customers. Through the study of

this project we are exposing vast technologies associated with fibre optics and

their influences on our life span. Fibre optics can be seen as newly born baby,

whose full application cannot be judged yet.We hoped that this project will serve as the knowledge guide for understanding

the enormous facts about the fibre optics and its modern concerns


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ACKNOWLEDGEMENT

We humbly acknowledge our best to all those who helped and guided us while this

project was underway. This is our maiden effort to present this project report in which

we were helped, guided and supported by our friends and teachers.

We wish to express our deepest gratitude to our Electronics teacher- Mrs. Moutusi

Mondal Roy of Dr. B. C. Roy Engineering College, Durgapur for his humble and

inspiring guidance throughout the preparation of the project report entitled fibre

OPTICS.

We are also thankful to Mrs. Sharmistha De Dutta, for her fruitful and unendingsupport and of course to the Humanities Department of DR.B.C.ROY Engineering

College for giving us an opportunity to present the topic.

It is their precious and effective suggestion in our work which constantly encouraged

us to go ahead and enabled us to give this project report its present shape.

We are also very thankful to our teachers and friends for giving their valuable time

and moral supports. We are also very much thankful to all our teachers who boosted

our confidence in completing this project report..


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LETTER OF CERTIFICATION

This is to certify that Amit Kumar(ECE,2nd

Year), Ashish Kumar(ECE,2nd

Year), Aakash Kumar(ECE,2nd Year), Vikash Kumar Singh(ECE,2nd Year),

Mayank(ECE,2nd

Year), Braja Gopal Bera (ECE,2nd

Year), have successfully

completed a project on FIBRE OPTICS under the guidance of Mrs.

Sharmistha De Dutta and Mrs. Moutusi Mondal Roy. .

Approved By :-

Mrs. Moutusi Mondal Roy Mr.A.K.Mukhopadhaya

(Lecturer of E.C.E.) (H.O.D. of E.C.E.)


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TABLE OF CONTENTS

1. Summary .. 7

2.

Introduction ..83. Brief History ..9

4. Theory of Operation 10

5. Construction Details 11

6. Propagation of Light in Optical Fibre ..12

7. Types of Optical Fibre ....13-14

7.1Step Index Fibre

7.1.1 Single Mode Step Index Fibre 13

7.1.2 Multi Mode Step Index Fibre..14

7.2

Graded Index Fibre.....148. Advantages of Fibre Optic over copper wire ..15

9. Field of Application ..16-19

9.1fibre Optic Interconnection16

9.2Gigabit Ethernet.16

9.3Independent Telecommunication Providers..17

9.4Fibre Optics for space..17

9.5Medical Fibre Optic18

9.6Fibre Optic for Shore Connectivity19

9.7

HDTV.19

10.Conclusion..20

11.Appendix21

11. References...22


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LIST OF ILLUSTRATION

Fig 1: Transmission of signal through optical fibre

Fig 2: Total Internal Reflection

Fig 3: Construction of Optical fibre

Fig 4: The Propagation of light in Optical fibre

Fig 5: Step Index fibre

Fig 6: Single Mode Step Index fibre

Fig 7: Multi Mode Step Index fibre

Fig 8: Graded Index fibre

Fig 9: Interconnections

Fig 10: Gigabit Ethernet

Fig 11: Telecommunication

Fig 12: Medical Purposes

Fig 13: Marine Utility

Fig 14: HDTV


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Summary

Fibre optics have become the industry standard for the terrestrial transmission of

telecommunication information. fibre optics will continue to be a major player in the delivery

of broadband services. Today more than 80 percent of the world's long-distance traffic is

carried over optical-fibre cables.

The principle of total internal reflection is used to propagate light sign Summarily. Light is

guided through the core, and the fibre acts as an optical waveguide. SMF and MMF cables

are constructed differently. MMF has a larger core diameter as compared to SMF. There are

two types of propagation for fibre-optic cable: multimode or single mode. These modes

perform differently with respect to both attenuation and time dispersion. SMF cable provides

better performance than MMF cable. The three primary propagation modes include

multimode step index, single-mode step index, and multimode graded index propagation.

In an optical communications system, information from the source is encoded into electrical

signals that can drive the transmitter. The transmitter consists of an LED or laser and is

pulsed at the incoming frequency. The fibre acts as an optical waveguide. At the detector, the

signals undergo an OE conversion, are decoded, and are sent to their destination. fibre-optic

system characteristics include attenuation, interference, and bandwidth characteristics. fibre-

optic systems are also secure from data tapping, and tampering can be detected far more

easily than with metallic-based transmission medium or free-space propagation.

Telecommunications applications of fibre-optic cable are widespread, ranging from global

networks to desktop computers. These involve the transmission of voice, data, and video over

distances of less than a meter to hundreds of kilometres, using one of a few standard fibre

designs in one of several cable designs. Carriers use optical fibre to carry analog phone

service. Cable television companies also use fibre for delivery of digital video services.

Intelligent transportation systems and biomedical systems also use fibre-optic transmission

systems. Optical cable is also the industry standard for subterranean and submarine

transmission systems. Not only telecommunication purpose, but fibre optics also left its

excellent mark on medical, military, space and many other important regions. So, throughout

the study of these project, we are elaborating all the above included discussions and topics.


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INTRODUCTION

Our current "age of technology" is the result of many brilliant inventions and discoveries, but

it is our ability to transmit information, and the media we use to do it, that is perhaps most

responsible for its evolution. Progressing from the copper wire of a century ago to todaysfibre optic cable, our increasing ability to transmit more information, more quickly and over

longer distances have expanded the boundaries of our technological development in all areas.

Todays low- loss glass fibre optic cable offers almost unlimited bandwidth and unique

advantages over all previously developed transmission media. The basic point-to-point fibre

optic transmission system consists of three basic elements: the optical transmitter, the fibre

optic cable and the optical receiver

Figure 01- Transmission of signal through optical fibre

The Optical Transmitter: converts an electrical analog or digital signal into a

Corresponding optical signal. Operates mostly at wavelengths of 850 or1300nm.

The Fibre Optic Cable: consists of one or more glass fibre, which act as waveguidesfor the optical signal.

The Optical Receiver: converts the optical signal back into a replica of the originalelectrical signal.

Since that time the use of fibre optics has increased dramatically. It is used to transmit voice,

television, images and data signals through small flexible threads of glass or plastic. These

fibre optic cables far exceed the information capacity of coaxial cable or twisted wire pairs.

They are also smaller and lighter in weightthan conventional copper systems and are immune

to electromagnetic interference and crosstalk. To date, fibre optics has found its greatest

applicationin the telephone industry.The future of fibre optics does look promising,

for its advantage.


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BRIEF HISTORY

Fibre optics rises dramatically from a piece of thin tread to miles of optical channels used for

enormous purposes. So, lets have a brief look at the growth of this technology:-

y1790s: Claude Chappe, French engineer, invented the "optical telegraph"

y1840s: Swiss physicist Daniel Collodon and French physicist Jacques Babinet showed that

light could be guided along jets of water for fountain displays.

y1930s: Heinrich Lamm, the first person known to have demonstrated image transmission

through a bundle of optic fibre.

y1954s: Abraham van Heel of the Technical University of Delft in Holland and Harold. H.Hopkins and Narender Kapany of Imperial College in London separately announced

imaging bundles in the prestigious British journal Nature.

y 1954-1959s: Lawrence Curtis, then an undergraduate at the University of Michigan,

developed glass-clad fibre.

y 1960s: glass-clad fibre had attenuation of about one decibel per meter, fine for medical

im334567aging, but much too high for communications.

y

196

1s: Elias Snitzer at American Optical, working with Hicks at Mosaic Fabrications,

demonstrated the similarity by drawing fibre with cores so small they carried light in only

one wave guide mode.

y December1964:

-With George Hockham, another young engineer who specialized in Antenna Theory,

Kao worked out a proposal for long distance communications over single model fibre.

y April 1,1966: The issue of laser Focus noted Kao's proposal.

- July 1966:

-Kao and Hockham forecast that fibre loss could be reduced below 20 dB/km attracted

the interest of the British Post Office.

y 1970s: Success in reducing fibre loss to 20 dB/km.


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THEORY OF OPERATION

The main principle behind the method of wave guidance in a fibre optics cable is the idea of

TOTAL INTERNAL REFL E CTION.

Figure 2- Total Internal Reflection

If a light ray passes from one medium with a refractive index ofn1 to another medium with a

refractive index ofn2, and n2 is larger than n1 , such as air to glass, the refracted wave in the

second medium will bend towards the normal. If n2 is less than n1, the wave will be bent

away from the normal to the surface. There is one instance, where the penetrating ray will not

deviate from its original path at all, that is, if it enters the medium perpendicular to the

surface or head on. In the case of n2 being less than n1, there is a point when the incident ray

will be totally internally reflected, that is, the ray will not enter the second material. If the

angle of incidence, measured from the normal, for the n2 not equal to n1, is gradually

increased the transmitted wave will continually bend away from the normal. There is an

angle, however, in which the refracted wave will be placed along the surface of the boundary

between the two media, and will not enter the second material, this is called the critical

angle,. A light ray will be reflected at the boundary for all angles of incidence greater than the

critical angle. As the incident angle of the ray is further increased, the refracted wave is

actually turned back into the first medium, and total internal reflection is achieved.

We can find the critical angle by putting Qc = 90 deg in Snells law of refraction:

n1 sin Qc = n2 sin 90deg(1)

Qc= sin-1

(n2 / n1)


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CONSTRUCTION DETAILS

Optical fibre is composed of several elements. The construction of a fibre optic cable consists

of a core,cladding,coating buffer, strength member and outer jacket. The optic core is

the light-carrying element at the centre. The core is usually made up of a combination of

silica and germanium. The cladding surrounding the core is made of pure silica. The cladding

has a slightly lower index of refraction than the core. The lower refractive index causes the

light in the core to reflect off the cladding and stay within the core. Index of refraction is the

ratio of the velocity of light in a vacuum to the velocity of light in a material. The speed of

light in a vacuum is equal to 300,000,000 meters per second. The higher the index of

refraction, the slower the speed of light through the material.

Index of Refraction = Light velocity (vacuum)

Light velocity (material)

Fibre is either single mode or multimode. Fibre sizes are expressed by

Using two numbers: 8/125. The first number refers to the core size in

Microns. The second number refers to the core size plus the cladding size

Combined.

Figure 3-Construction of optical fibre

Several layers of buffer coatings protect the core and the cladding. The layers act as a shockabsorber to protect the core and cladding from damage. A strength member, usually armid is

around the buffer layers. To prevent pulling damage during installation the strength member

is added to give critical tensile (pulling) strength to the cable. The outer jacket protects

against environmental factor


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PROPAGATION OF LIGHT IN OPTICAL

FIBRE

Figure 4- The Propagation of Light in Optical fibre

The angle Q in the Figure is called the Acceptance Angle. Any light entering the fibre at less

than this angle will meet the cladding at an angle greater than critical angle. If light meets the

inner surface of the cladding (the core - cladding interface) at greater than or equal to

critical angle then TIR occurs. So all the energy in the ray of light is reflected back into the

core and none escapes into the cladding. The ray then crosses to the other side of the core

and, because the fibre is more or less straight, the ray will meet the cladding on the other side

at an angle which again causes TIR. The ray is then reflected back across the core again and

the same thing happens. In this way the light zigzags its way along the fibre. This means that

the light will be transmitted to the end of the fibre.

In reality the light which enters the fibre is a focused beam, consisting of many millions of

"rays" behaving in a similar way. They all zigzag along the core of the fibre, crossing over

each other, and filling up the core with light. A pulse of light travelling along the core of the

fibre is really a bundle of these rays.

Optical fibre act as a guide for light. Once light enters the fibre, it moves in the same

direction as the fibre. As the fibre can be bent, light can thus be bent around corners by using

optical fibre.


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TYPES OF OPTICAL FIBRE

There are two main fibre types:

1) Stepindex

2) Graded index

Step Index fibre

Step index fibre is so called because the refractive index of the fibre steps up as we

move from the cladding to the core of the fibre. Within the cladding the refractive index is

constant, and within the core of the refractive index is constant.

Figure 5- Step Index fibre

Single Mode Step Index fibre

Because its core is so narrow, a Single Mode fibre can support only one mode. This is called

the "Lowest Order Mode".

Figure 6-Single mode Step Index fibre


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Multimode Step Index fibre

Although it may seem from what we have said about Total Internal Reflection that any ray

of light can travel down the fibre, because of the wave nature of light, only certain ray

directions can actually travel down the fibre. These are called the "fibre Mode". In a

multimode fibre many different modes are supported by the fibre.

Figure 7- Multimode Step Index fibre

Graded Index fibre:

Graded Index fibre has a different core structure from single mode and multimode step index

fibre. Whereas in a step-index fibre the refractive index of the core is constant throughout the

core, in a graded index fibre the value of the refractive index changes from the centre of the

core onwards. In fact it has a Quadratic Profile. This means that the refractive index of the

core is proportional to the square of the distance from the centre of the fibre.

Figure 8- The Graded Index fibre


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Advantages of Fibre Optic Systems over co-

axial orcopper wire:-

The three Elements (Optical transmitter, Optical receiver, fibre optic cable) used in fibre

optic transmission systems, offer a wide range of benefits not offered by traditional copper

wire or coaxial cable. These include:

1. The ability to carry much more information and deliver it with greater fidelity than either

Copper wire or coaxial cable.

2. Fibre optic cable can support much higher data rates, and at greater distances, than coaxial

cable, making it ideal for transmission of serial digital data.

3. The fibre is totally immune to virtually all kinds of interference, including lightning, andwill not conduct electricity. It can therefore come in direct contact with high voltage

electrical equipment and power lines. It will also not create ground loops of any kind.

4. As the basic fibre is made of glass, it will not corrode and is unaffected by most chemicals.

It can be buried directly in most kinds of soil or exposed to most corrosive atmospheres in

chemical plants without significant concern.

5. Since the only carrier in the fibre is light, there is no possibility of a spark from a broken

fibre. Even in the most explosive of atmospheres, there is no fire hazard, and no danger of

electrical shock to personnel repairing broken fibre.

6. fibre optic cables are virtually unaffected by outdoor atmospheric conditions, allowing

them to be lashed directly to telephone poles or existing electrical cables without concern for

extraneous signal pickup.

7. A fibre optic cable, even one that contains many fibre, is usually much smaller and lighter

in weight than a wire or coaxial cable with similar information carrying capacity. It is easier

to handle and install, and uses less duct space.

8. Fibre optic cable is ideal for secure communications systems because it is very difficult totap but very easy to monitor. In addition, there is absolutely no electrical radiation from a

fibre.

The next Points will show how fibre optic cables are able to provide all these advantages and

why fibre-optics are steadily replacing copper wire as an appropriate means of

communication signal transmission.


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FIELD OF APPLICATIONS

Fibre Optic Interconnects

Interconnections are one of the largest and most widely used

areas for fibre optic cables and assemblies. An interconnect is

defined as the physical connection of two or more fixtures

through which communication is possible. Interconnects range

from simple, simplex patch cords to multi-channel distribution

and backbone cables and virtually everything in between. Most

interconnects are used for smaller, localized network or system

structures, linking similar machines, complimentary devices,

and/or data communications from one system to another.

Figure 9 -Interconnection

Typical interconnect products are centred on a variety of industry standard cable assemblies

that move, relay, or distribute data from point-to-point.

Gigabit Ethernet

Gigabit Ethernet solutions have become a necessity with the accelerating growth of LANtraffic, pushing network administrators to look for higher

speed network technologies to meet the demand for more

bandwidth.

Gigabit Ethernet applications supported by fibre optics

are now transmitting signal reliably at 10Gbps, up to

10,000 meters using single mode systems, and well over

that for Gigabit and multi-gig transmission rates. With

multimode systems, fibre optics will push 10Gbps

transmission between 26 and fibre optic products workvery well for troubleshooting network issues for a number of reasons:

y Low cost, high-bandwidth solution Figure 10- GigabitEthernet

y Large network simulation capabilities

y Pure optical signal testing allows for more precise results as opposed to optical to

electrical back to optical testing


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Independent Telecommunication

Providers

The independenttelecommunication providers segment is an area of

the industry that provides service(s) in rural areas, typically supporting

residential and small to medium businesses. The services offered in

these areas can range from basic telephone to triple play depending on

the provider, subscriber location, and service availability.

Independent Telecommunications Providers have been able to

offer an entire suite of services to clients, previously unavailable over

traditional copper lines. Expanded service can include high-speed

internet access, broadcast television (high definition in some cases),

voice over internet protocol phone service, and security over a single

broadband connection. Availability of the various components

within the expanded services area remains dependent on each service provider; however,

more and more of these various services are becoming available in rural locations nationwide.

Fibre Optics for Space

Over the last several years, fibre optics has become increasingly popular in space

environments as a medium of choice for a variety of applications. fibre offers some distinct

advantages over other mediums including:

y Immunity to EMI & RFI

y Low attenuation of light power over long distances

y Wide transmission bandwidth (~10 100 Gbps)

y Small physical size and weight

y Electrical insulation from chemical corrosion

y Analog and digital transmission

Figure11-telecommunication


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Medical Fibre Optics

fibre optics have been used in the medical industry for years. The physical characteristics of

fibre make it a natural choice for many different applications. Commonly used for

illumination, flexible image bundles, light conductors, flexible light guides, laser delivery

systems, and equipment interconnects, fibre optics provide a very compact, flexible conduit

for light or data delivery in equipment, surgical, and instrumentation applications.

y Medical Research

Medical research covers a wide range of applications and

areas of study within the medical field. Often, fibre optic

products in this area are designed to be very application

specific as each products requirement is intended to

support and/or test a theory, procedure, or instrument.

While some applications share various product attributes

with another product, the vast majority require precise

and unique characteristics achieved through specialty

product design.

Figure 12 Medical Purposes

y

Medical Instruments

Medical Instruments utilize fibre optics for a variety of applications including illumination,

image transfer, and laser signal delivery.

examination lights

FO headlight

Vet otoscope

Laryngoscope (blade illumination)

Anoscope (with annular illumination)

Binocular indirect ophthalmoscope

Anemoscope

Microscope illumination

Heart catheter


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Fibre Optics for Ship to Shore Connectivity

fibre optics for ship to shore applications are designed to provide

data, phone, and other services to docked ships via umbilical

cable to landline connection. These connections allow high

speed, high bandwidth communications to and from the vessel,

without using shipboard wireless transmit/receive systems.

For this application, fibre optics offer some distinct advantages

with size, weight, performance, and durability.

Figure 12-Marine utility

HDTV

HDTV (high definition television) is the broadcasting of a higher

resolution format than possible with traditional analog television

broadcasting. A form of digital television, HDTV is a very bandwidth

intensive application requiring maximum allowable speed and data volume

transfer.Originating with HD camera and video capture/processing

equipment, television networks, service providers, and production

companies utilizing fibre optics as the support and distribution structure all

the way to the subscriber premises.

Figure 13-HDTV


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CONCLUSION

Science and technology has grown by leaps and bounds and we are heading towards a future,

where fiction at present will turn into realities. Optical fibre has been one of the mostappreciable invention in our era.

Throughout the whole processes of building this report, we indulge ourselves fully in

understanding the interesting facts about the fibre optics. fibre optics is really a great product

that come our hand far our modern utilities. It can be used to connect , communicate and

cure.

fibre optics awaits lots of further uses that are still in research and processing.


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APPENDIX

TIR :- Total Internal Refle

c

tion RI :-Refractiveindex

EMI :-Electro Magnetic Interference

RFI :-Radio Frequency Interference

Gbps :-Giga bytes per second

HDTV :-High Definition Television


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REFERENCES

Optical fibre communication by SENIOR Telecommunication by VISHWANATHAN

http://en.wikipedia.org/wiki/Fibre optics

Fibre Optics on Google

http://en.wikipedia.org/wiki/Fibre optics communication

Images of optical fibres on Google

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