OPTICAL FIBRE CABLEprepared by,

Hasmath Naseera.A

DEFINITION:

An optical fiber cable is a CABLE

containing one or more optical fibers that

are used to carry light.

It is made of glass or plastic and transmits

signals in the form of light.

CHARACTERISTICS

Light travels in a straight line as long

as it is moving through a single

uniform substance.

If a ray of light travelling through one

substance & suddenly enters another

substance, the ray changes direction.

REFRACTION:

If a ray of light travelling through one

substance suddenly enters

another(more or less dense)

substance, its speed changes

abruptly, causing the ray to change

direction.

This change is called Refraction

CRITICAL ANGLE:

A beam of light moving from a more

dense medium to less dense medium.

At some point, the change in the

incident angle results in a refracted

angle of 90 degrees. The incident

angle at this point is known as

CRITICAL ANGLE.

Representation:

REFLECTION:

When the angle of incidence becomes

greater than the critical angle a new

phenomenon occurs called

REFLECTION.

Light no longer passes into the less

dense medium at all.

Angle of incidence = Angle of

reflection

PROPAGATION MODES

MULTIMODE

Multimode is so named because

multiple beams from a light source

move through the core in different

paths.

The beams within the cable depends

on the structure of core.

MULTIMODE STEP INDEX

FIBER

In multimode step index fiber, the

density of the core remains constant

from the centre to the edges.

A beam of light moves through its

constant density in a straight line until

it reaches the interface of the core and

the cladding.

Multimode step index(coned)..

At the interface there is abrupt change

to a lower density that alters the angle

of the beam’s motion.

The term STEP-INDEX refers to

sudden change.

MULTIMODE GRADED-INDEX

FIBER The multimode graded index fiber,

decreases the distortion of signal

through the cable.

The word index refers to the index of

refraction.

DENSITY OF INDEX FIBER

Index of refraction refers to density. A

graded index fiber is one with varying

densities.

Density is highest at the centre of the

core and decreases gradually to its

lowest at the edge

SINGLE MODE:

It uses step index fiber and a highly

focused source of light that limits

beams to a small range of angles.

It is manufactured with with a much

smaller diameter than that of

multimode fibers,and with substantially

lower density(index of refraction).

FIBER SIZES

Optical fibres are defined by the ratio

of diameter of their core to the

diameter of their cladding, both

expressed in terms of micrometers.

TYPE:50/125

CORE:50.0um

CLADDING:125um

MODE:multimode,graded index

FIBER SIZES:

TYPE CORE(um) CLADDING(u

m)

MODE

50/125 50.0 125 Multimode,gr

aded index

62.5/125 62.5 125 Multimode,gr

aded index

100/125 100.0 125 Multimode,gr

aded index

7/125 7.0 125 Single mode

CABLE COMPOSITION

cladding

Core

Optical

fiber

Outer

jacket

CABLE COMPOSITION:

The outer jacket is made of either PVC or teflon.

Inside the jacket are Kevlar strands to strengthen the cable.

Kevlar is a strong material used in fabrication of bulletproof vests.

Below the kevlar is another plastic coating to cushion the fiber.

The fiber is at the centre of the cable, and it consists of cladding and core.

Cable composition:

Operation:

FIBER OPTIC

CONNECTORS

FIBRE OPTIC

CONNECTORS: The subscriber channel(SC) is used

for cable TV.It uses a push/pull locking

system.

The straight-tip (ST) connector is used

for connecting cable to networking

devices.

It uses a bayonet locking s/m and it is

more reliable than SC.

Eg:MT-RJ

Connector:

PERFORMANCE:

Attenuation is flatter than in case of

twisted- pair cable and co-axial cable.

The performance is such that we need

fewer repeaters while using fiber optic

cable.

Performance characteristics:

APPLICATIONS:

Fiber optic cable is backbone of

networks because of its wide

bandwidth and it is cost -

effective.eg:SONET network

Using Wavelength Division

Multiplexing (WDM),we can transfer

data at a rate of 1600Gbps.

Cable TV companies

LAN networks such as 100Base-FX

network &1000Base-X.

ADVANTAGES:

Higher Bandwidth

Less signal attenuation

Immunity to electromagnetic

interference

Resistance to corrosive materials

Light Weight

Greater immunity to tapping

DISADVANTAGES:

Cost

Installation/maintainance

Fragility

Unidirectional light propagation

THANK YOU…