2. Tableofcontents
What is OPTICAL FIBRE?
Evolution of OPTICAL FIBRE
Components of OPTICAL FIBRE
Total Internal Reflection
How OPTICAL FIBRE works?
Types of OPTICAL FIBRE
Advantages and Disadvantages of OPTICAL FIBRE
3. WhatisOPTICALFIBRE?
Fiber optics (optical fibers) are long, thin strands of very pure
glass about the diameter of a human hair.
They are arranged in bundles called optical cables and used to
transmit light signals over long distances.
4. EVOLUTIONOFOPTICALFIBRE
1880 – Alexander Graham Bell
1930 – Patents on tubing
1950 – patents for two layer glass wave guide
1960 – Laser first used as alight source
1965 – High loss of light discovered
1970 – Refining of manufacturing process
1980 – OPTICAL FIBRE becomes backbone of long distance
telephone networks
5. COMPONENTSOFOPTICALFIBRE
CORE – thin glass centre where the light
travels.
CLADDING – outer optical material that surrounds the core.
BUFFER COATING – plastic coating that protects the fibre.
7. TOTALINTERNALREFLECTION(TIR)
To understand ‘how optical fibre works’ we have to understand
the concept of TIR.
When the angle of incidence becomes larger than the critical
angle, no refraction occur. The entire light is reflected back into
the denser medium. This is known as TOTAL INTERNAL
REFLECTION.
9. HOWOPTICALFIBREWORKS?
Light that enters the core at one end of the optical fibre goes
straight and hits the inner wall(cladding) of fibre optics. The
angle of incidence with cladding is greater than the critical angle,
light is totally reflected into the fibre optics until it hits the inner
wall again, and so on.
As explained above, this phenomena is TOTAL INTERNAL
REFLECTION.
12. SINGLEMODEFIBRE
Single mode fiber is optical fiber that is designed for the
transmission of a single ray or mode of light as a carrier .
It is used for long-distance signal transmission.
This fibre is used in telecom and CAT V networks.
14. MULTI-MODEFIBRE
Each optical fibre in a multi-mode cable is about 10 times thicker
than fibre optics used in a single mode cable. This means light
beams can travel through the core by following different
paths,hence the name multi-mode.
Multi-mode cable can send information only over relatively short
distances and are used to link computer networks together.
16. ADVANTAGES
Bandwidth - Fibre optic cables have a much greater
bandwidth than copper cables. The amount of information that
can be transmitted per unit time of fibre over other transmission
media is its most significant advantage.
Low Power Loss - An optical fibre offers low power loss. In
comparison to copper; in a network, the longest recommended
copper distance is 100m while with fibre, it is 2000m.
17. Interference- Fibre optic cables are immune to
electromagnetic interference. It can also be run in electrically
noisy environments without concern as electrical noise will not
affect fibre.
Size- In comparison to copper, a fibre optic cable has nearly 4.5
times as much capacity as the wire cable has and a cross sectional
area that is 30 times less.
Weight - Fibre optic cables are much thinner and lighter than
metal wires. They also occupy less space with cables of the same
information capacity. Lighter weight makes fibre easier to install.
18. Safety- Since the fibre is a dielectric, it does not present a spark
hazard.
Security - Optical fibers are difficult to tap. fibre is the most
secure medium available for carrying sensitive data.
Flexibility - An optical fibre has greater tensile strength than
copper or steel fibers of the same diameter. It is flexible, bends
easily and resists most corrosive elements that attack copper
cable.
19. DISADVANTAGES
COST- Cables are expensive to install but last longer than
copper cables.
TRANSMISSION- Transmission on optical fiber requires
repeating at distance intervals.
20. FRAGILE - Fibers can be broken or have transmission loses
when wrapped around curves of only a few centimeters
radius. However by encasing fibers in a plastic sheath, it is
difficult to bend the cable into a small enough radius to break the
fiber.
