Optical Fibres

• Optical fibers are long, thin strands of very pure glass usually the diameter of a human hair; 120 µm.

• They are arranged in bundles called optical cables and used to transmit light signals over long distances. (up to 50 km.)

• Core – thin glass center of the fiber .

• Cladding – outer optical material made from glass surrounding the core.

• Buffer Coating – plastic coating that protects the fiber .

• Jacket – The bundles are protected by the cables’ outside covering called jacket.

1.Core

4.Jacket

3.Buffer

2.Cladding

Parts of the Optic Fibre

Ɵ 1

Ɵ 2

• Let a ray of light be incident on the fibre making the critical angle with the axis as shown.

• The light ray passes passes into the fibre.

• This ray forms the incident angle.• If the incident theta is greater than the

critical angle then the ray suffers total internal reflection.• So all the energy in the ray of light is reflected in the core and none escapes into the cladding.

• The reflection get repeated throughout the fibre leading to a total internal reflection.

How light is transmitted through the fibre optic.

Types of Optical Fibers.Optical fibers come in two types:

• Single-mode fibers are used to transmit one signal per fiber (used in telephone and cable TV). They have small core (9 microns in diameter) and transmit infra-red light from laser. • Multi-mode fibers are used

to transmit many signals per fiber (used in computer networks). They have larger cores (62.5 microns in diameter) and transmit infra-red light from LED.

Single-mode fibers Multi-mode fibers

Small Diame

ter

Small Diame

ter

Light Weigh

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Noise Immunity

Diminished Loss

of Energ

y

Large Capacity of Transmitting Line

Less Space used.

Easy Multi Fibre Cablin

g.

Easy Bendi

ng

Easy Installation

Less Interference

Wide Bandw

ith

Long repeat

less range

of energy

.

Light Weigh

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Characteristics and Advantages

1. It has a very high information carrying capacity.

ADVANTAGES OF OPTICAL FIBERS

8. Power usage is less compared to many other cables.

2. It has less attenuation.

3. The cost of production is less compared to copper. Less Signal Degradation occurs throughout the fibre.

4. Greater safety and immunity to EMI or RFI, moisture and corrosion.

5. It’s flexible and easy to install in tight conduits.

6. It’s dielectric in nature so can be laid in electrically sensitive surroundings.

7. You wont come across any situations of cross talking or any disturbances.

Disadvantages

• Fiber optics are that the cables are expensive to install.

• The termination of a fiber optic cable is complex and requires special tools.

• They are more fragile than coaxial cable.

It’s the backbone of many long distance communications. It’s widely used in computer data communications and networks. (LAN, WAN etc..) It’s used in many lighting systems.It’s used in video and data transmissions. It’s used in transmitting broadband signals The cables are ideally suited for high-reliability settings such in commercial and military jet aircraft, satellite and other space-based applications.It’s used by Surgeons to view organs inside the body that cannot be viewed directly.It’s also used in the biomedical industry.

Optic Fibre and it’s applications

Done By :Huda, Disha, Subhan &

Waris…