OPTICAL FIBRE COMMUNICATION

P.RANJIT 12W61A0485

CONTENTS

INTRODUCTION Cross section area of optical fibre Materials used for optical fibre Block diagram of optical fibre with transmitter and receiver blocks Working principle Advantages Disadvantages Applications in various fields

INTRODUCTION

Optical fibre is a coaxial cylindrical arrangement of two homogenous dielectric material

It is flexible, transparent fibre made of silica or plastic slightly thicker than human hair

Its working is based on Total Internal Reflection they permit transmission over longer distances and at higher

bandwidths (data rates) than wire cables. Specially designed fibres are used for a variety of other applications,

including sensors and fibre lasers.

Cross section area of optical fibre

Optical fibre consists of three layers

CoreCladdingProtective or jacket layer

MATERIALS USED FOR OPTICAL FIBER

Optical fibers are generally made up of glass and plastic

There are different types of glass fibers are there are Glass fibers

CORE CLADDINGGeo2+sio2 sio2

Sio2 B2o3-sio2

MATERIALS USED FOR OPTICAL FIBER

Halide Glass FibersActive Glass Fibers Chalcogenide Glass Fibers

Plastic fibers

POF (plastic optic fibre)PMMA (poly methyl metha crylate)

PFP (pre fluorinated polymers)

Block diagram

Working Principle

As the angle of incidence is beyond the critical angle, then the light ray gets reflected with in the denser medium rather than causing refraction. This is called ‘TOTAL INTERNAL REFLECTION’

TOTAL INTERNAL REFLECTION Observed in optical fibre

Advantages  Weight - Fibre optic cables are much thinner and lighter

than metal wires.   Safety - Since the fibre is a dielectric, it does not present a

spark hazard.    Flexibility - An optical fibre has greater tensile strength

than copper or steel fibres of the same diameter.  Cost - The raw materials for glass are plentiful, unlike

copper.  This means glass can be made more cheaply than copper.   

Disadvantages

 Cost - Cables are expensive to install but last longer than copper cables. 

 Transmission - transmission on optical fibre requires repeating at distance intervals. 

 Protection - Optical fibres require more protection around the cable compared to copper.

Affected by chemicals - The glass can be affected by various chemicals including hydrogen gas (a problem in underwater cables.)

APPLICATIONS

Telephones Internet LANS-Local area networks CATV-For video, voice and internet

connections Security-closed circuit TV and intrusion

sensors

APPLICATIONS

IN MEDICAL FIELD For viewing internal parts of body with

instruments like fibre scope , bronchoscope Dermatology-for wrinkle and hair removal