Optical fibers transmit light signals over long distances and are made of thin strands of glass. They have a core that light travels through and a cladding layer surrounding the core that reflects the light through total internal reflection. Optical fibers come in single-mode or multi-mode varieties and are used widely in telecommunications and computer networking due to their high bandwidth capacity and immunity to electromagnetic interference. While expensive to initially install, optical fibers have advantages over electrical cables including lower attenuation over long distances and flexibility.
Indexing Structures in Database Management system.pdf
Optical Fibres
1.
2. • 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.)
3. • 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 . 1.Core
• Jacket – The bundles are 2.Cladding
protected by the cables’ outside
covering called jacket. 3.Buffer
4.Jacket
4. • 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.
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5. Types of Optical Fibers.
Optical fibers come in two types:
Single-mode fibers Multi-mode fibers
• 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.
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7. ADVANTAGES OF OPTICAL FIBERS
1. It has a very high information carrying
capacity.
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.
8. Power usage is less compared to many other cables.
8. 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.
9. 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.
