fiber optics

1. FIBER OPTICS

2. INTRODUCTION
• A Fiber – optic cable is a technology that uses glass (or
plastic) threads (fiber) to transmit data.It is made up of 100
or more incredibly thin strands of glass or plastic fibers
known as optical fibers.
• Each one is less than a tenth as thick as human hair and can
carry 10 million telephone calls.
• Optical fibers are widely used in fibers- optic
communication, which permits transmission over longer
distances and At higher data rates than other forms of wired
& wireless communications.

3. CLADDING
• The cladding’s job is to keep the light signals inside the core.
• It can do this because it is made of a different type of glass
to the core.
• Light travels slower in the cladding than in the core.
• Any light that tries to leak into the cladding tends to bend
back inside the core.

4. TOTAL INTERNAL REFLECTION
• Light travels down a fiber –optic cable by bouncing
repeatedly off the walls.
• Each tiny photon i.e., particle of light bounces down the pipe
like bobsleigh down the pipe like an ice run.
• We may expect a beam of light , travelling in a clear glass
pipe, simply to leak out of edges.
• But if light hits at a really shallow angle (less than 42
degrees), it reflects back in again – as though the glass were
really a mirror.
• This phenomenon is called Total internal reflection.

5. TYPES OF FIBER OPTICS
• Other fibers carry light signals down them in what are called
MODES.
• That sounds technical but it just means different ways of
travelling : a mode is simply the path that a light beam
follows down the fiber.
• There are generally two modes of fiber optics:-
• 1. Single - mode fiber optic.
2.Multi – mode fiber optic.

6. SINGLE – MODE FIBER OPTIC
• The simplest type of optical fiber is called
single-mode.
• It has a very thin core about 5 – 10 micron
(millionths of a meter) in diameter.
• In single –mode fiber , all signals travel straight
down the middle without bouncing off the
edges
• Cable TV ,Internet, and Telephone signals are
generally carried by single- mode fibers ,
wrapped together into a huge bundle.
• Cables like this can send information over 100
km(600 miles).
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7. MULTI – MODE FIBER OPTIC
• Another type of fiber- optic cable is
called multi – mode.
• Each optical fiber in multi- mode cable is
about 10 times bigger than one in a
single – mode cable.
• This means light beams can travel
through the core by following a variety
of different paths(purple, blue , and
green lines).
• Multi – mode cables can send
information only over relatively short
distances.
• It is used to link computer networks
together.
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8. ADVANTAGES
• Low cost in long run.
• Low loss of signals – less
transmission over long distance
is possible.
• Large data carrying capacity.
• No electro-magnetic radiation.
• Low weight.
• Signals contain very little power.
• No cross- talks between cables.
DISADVANTAGES
• High investment cost
• Need for more expensive
optical transmitters &
receivers.
• More difficult and
expensive to split than
wires.

9. AREAS OF FIBER OPTICS
• Tele – Communication.
• Local Area Networks.
• Cable TV.
• CCTV.
• Optical fiber sensors.