INTRODUCTION

• Fibre optic technology is one of the fastest growing

technology.

• Optical fibre draw more interests of researchers and

engineers for its valuable characteristics.

• It is mainly used to sense the physical and chemical

properties such as strains, vibrations, accelerations, linear

and rotary position.

• It is also used to sense temperatures, pressures, determination

of pH, refractive index of liquid solution, pipeline condition

monitoring etc.

DEFINITION

• An Optical fibre is a transparent guiding medium or material

which guides the information carrying light waves.

• It is made of glass or plastic.

• It can function as a light pipe to transmit light between the

two ends of the fibre.

• Optical fibres are widely used in fiber-optic

communications.

• The field of applied science and engineering concerned with

the design and application of optical fibres is known as

Fibre optics.

HISTORY

• In the 1840s, physicists Daniel Collodon and Jacques

Babinet showed that light could be directed along jets of

water .

• In 1854, John Tyndall, physicist, demonstrated that light

could travel through a curved stream of water.

• Alexander Graham Bell patented an optical telephone system

called the photo phone in 1880.

PRINCIPLE OF OPERATION

• Index of refraction: It is a way of measuring the speed of

light in a material. Light travels fastest in a vacuum, such

as in outer space

• Total Internal Reflection: When light is travelling in an

optically dense medium hits a boundary at a steep angle the

light is completely reflected. This is called total internal

reflection.

SINGLE AND MULTIMODE FIBRES

• Single-mode Fibre: In optical fibre technology, single mode

fibre is optical fibre that is designed for the transmission of a

single ray or mode of light as a carrier and is used for long-

distance signal transmission.

• Multi-mode Fibre: In optical fibre technology, multimode

fibre is optical fibre that is designed to carry multiple light

rays or modes concurrently, each at a slightly different

reflection angle within the optical fibre core

CLASSIFICATION OF OPTICAL FIBRE

• Optical fibres are classified in to two types:

• 1.Step-Index Optical Fibre:The Refractive index of core

and cladding of a step index fibre is constant.

• Graded-Index Optical Fibre: In this type of fibre cone has

a non-uniform refractive index that gradually decrease

from the centre towards the core cladding interface

Attenuation• Attenuation is the loss of the optical power. It takes place in

Optical fibre due to elements like coupler, splices, connector and

fibre itself.

• Attenuation may be categorised as Intrinsic and Extrinsic. The

specific attenuation actually depends on the wave length of the

radiation travelling along the Optic fibre.

Applications of Fiber Optics

Fiber Optic Technology has grown tremendously over the years and

today can be found in many surprising places.

Main Applications of Fiber Optics are:

Communication Systems

Medicine

Sensors

Military

Electronics

Applications of Fiber Optics in Communication Systems.

• Fiber-optic communication is a method of transmitting

information from one place to another by sending pulses of light

through an optical fiber.

• Optical fiber is used by many telecommunications companies to

transmit telephone signals, Internet communication, and cable

television signals.

Process of Communication

• The process of communicating using fiber-optics involves the

following basic steps:

1. Creating the optical signal involving the use of a transmitter,

2. Relaying the signal along the fiber, ensuring that the signal does

not become too distorted or weak,

3. Receiving the optical signal, and converting it into an electrical

signal.

Technology Modern fiber-optic communication systems generally include an

Optical transmitter : to convert an electrical signal into an

optical signal to send into the optical fiber.

TechnologyA Cable: containing bundles of multiple optical fibers.

An Optical Receiver: to recover the signal as an electrical signal.

Fiber Optic Communication System

Advantages of Optical Fiber Communication

The life of fibre is longer than Copper wire.

Handling and Installation costs of Optical fiber are very nominal.

It is unaffected with electromagnetic Interference.

Attenuation in optical fibre is lower than coaxial cable or twisted pair.

There is no necessity of additional equipment for protecting against

grounding and voltage problems.

As it does not radiates energy any antenna or detector cannot detects it

hence provides signal security.

Extremely wide band width.

Applications of Fiber Optics in Medicine

• Fiber optics have been used in the medical industry for years. The

physical characteristics of fiber make it a natural choice for many

different applications.

• Fiber optics provide a very compact, flexible conduit for light or

data delivery in equipment, surgical, and instrumentation

applications.

Applications• Traditional medical fiber optic applications include:

Light therapy

Ophthalmic lasers

Lab and clinical diagnostics

Endoscopy

surgical microscopy

Dental hand pieces

Applications in Sensors• A fiber optic sensor is a sensor that uses optical fiber either as the

sensing element or as a means of relaying signals from a remote

sensor to the electronics that process the signals .

• They are widely used in sensors for sensing and measuring of

acoustic fields, magnetic fields,currents,acceleration,strain etc.,

Applications • Fibre Optic Sensor holds particularly for harsh environments, such

as sensing in high-voltage and high-power machinery, or in

microwave ovens.

• Bragg grating sensors can also be used to monitor the conditions

e.g. within the wings of airplanes, in wind turbines, bridges, large

dams, oil wells and pipelines.

Applications in Military• Fiber optic products are used in a variety of military applications.

• The Military uses fiber optic technology for a wide variety of air,

sea, ground, and space applications.

• Military fiber optic applications are highly specialized.

Applications in Electronics

• Fiber optic products for the electronics market cover a wide range

of applications.

• Typically used in professional audio/video, alarm/security, and

OEM component connections.

Future Applications• In Research field, fiber is enabling the creation of clocks that are

more accurate before. By combining a laser with an optical fiber,

these clocks allow scientists to measure time accurately than they

have been able to previously, enabling better, more precise.

Disadvantages of Fiber Optics

• Highly skilled staff would be required for maintenance.

• Only point to point working is possible on Optical fibre.

• Precise and costly instruments would be required.

• Costly and Expensive.

• Jointing of Fibers is a Time consuming process.

Conclusion• The age of optical communications is a new era.

• At present there are many optical fiber communication links

throughout the world without using optical solutions.

• We can expect a great revolution in optical fiber communication

within a few years by means of solutions.