Optic Fibres Ppt

8/8/2019 Optic Fibres Ppt

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History

Structure

TypesAttenuation

Construction

Application

Electric Transmission v/s

Optic Fibre Transmission.



Daniel Colladen described it as

Òlight fountainÓ or Òlight pipeÓ

in 1852.

Later was followed by use in

dentistry,radio and televisioncables,gastroscope.



An optical fiber is a glass or

plastic fiber that carries

light along its length.



The basic structure of optic

fiber consists of 4 layers:

Jacket

Buffer

Cladding

Core



Multi modefibers

Single modefibers



Multi mode fibersÔSupport many

propagation paths ortransverse modes .

ÔLarger corediameter(>50mm).

ÔUsed for shortdistancecommunication links.

Single modefibers

Ô Support a singlemode .

Ô Smaller core

diameter(<10mm).Ô Used for long

distancecommunicationlinks.



Attenuation in fiber optics, also known as

transmission loss, is the reduction in

intensity of the light beam (or signal) with

respect to distance travelled through atransmission medium.

Attenuation in optical fiber is caused

primarily by both scattering and absorption.

Rough and irregular surfaces, even at the

molecular level, can cause light rays to be

reflected in random directions. This is called

diffuse reflection or scattering.



Standard optical fibers are made by

first constructing a largediameter

preform, preform tip is then heated and

the optic fiber is pulled out as a string.

Fiber optic coatings are applied to the

outside of the fiber during the drawing

process. The coatings protect the verydelicate strands of glass fiber

oAllowing it to survive the rigors of

manufacturing, proof testing, cabling and



Fiber optic communication:Information is

transmitted by sending light through optical

fibers.

E.g. Telephone signals, Internet

communication, Cable television signals.

Fiber optic sensors :Used in remotesensing which otherwise is unaccesible.

E.g. Temperature inside aircraft jet engines.

Temperature of electrical transformers.



Used in imaging optics in endoscope for

medical surgery or inspecting jet engine

interiors.

Used to transmit light from aspectrometer to a substance.

Fiber amplifiers or laser applications.

Ophthalmology andD

entistry.Widely used in illumination applications.

Used for decorative applications.

E.g.Swarovski boutiques.



Electrical transmission is often preferred

because of its;

Lower material cost, where large quantities

are not requiredLower cost of transmitters and receivers

Capability to carry electrical power as well

as signals (in speciallydesigned cables)Ease of operating transducers in linear

mode.



Immunity to electromagnetic interference,including nuclear electromagnetic pulses.

High electrical resistance.

Lighter weight²

important, for example, inaircraft.

No sparks² important in flammable or

explosive gas environments.

Not electromagnetically radiating, and

difficult to tap without disrupting the

signal² important in highsecurity

environments.

Optic Fibres Ppt

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