Fiber optics use thin strands of glass to transmit light signals for communication. They have a core that carries the light and a cladding that reflects the light down the core. There are two types of fibers - single-mode for infrared laser light and multi-mode for infrared LED light. Light travels through total internal reflection down the core due to the cladding not absorbing any light. Fiber optic systems have transmitters that encode light signals, fibers that conduct them, and receivers that decode the signals. Fiber optics offer advantages like lower costs, higher bandwidth, lighter weight, and flexibility compared to copper cables.

1. How Fiber Optics Work
s1200008 Kazuya Watanabe
December 9, 2012

2. What are Fiber Optics?
Fiber optics are long, thin strands of very pure glass.
it has the following parts :
Core : Thin glass center of the fiber where the light travels
Cladding : Outer optical material surrounding the core that
reflects the light back into the core
Buffer coating : Plastic coating that protects the fiber from
damage and moisture
Optical fibers types
1. Single-mode fibers : it have small cores and transmit infrared
laser light
2. Multi-mode fibers : it have larger cores and transmit infrared
light from light-emitting diodes

3. How transmit light
Total internal reflection : The light in a fiber-optic cable travels
through the core by constantly bouncing from the cladding
Because the cladding does not absorb any light from the core, the
light wave can travel great distances.
But, some of the light signal degrades within the fiber, mostly due
to impurities in the glass.

4. A Fiber-Optic Relay System
Constitution of fiber-optic relay systems
1. Transmitter : Produces and encodes the light signals
It receives and directs the optical device to turn the light ”on”
and ”off” in the correct sequence, thereby generating a light
signal.
2. Optical fiber : Conducts the light signals over a distance
3. Optical regenerator : May be necessary to boost the light
signal
4. Optical receiver : Receives and decodes the light signals
It takes the incoming digital light signals, decodes them and
sends the electrical signal to the other user’s computer.

5. Advantages of Fiber Optics
Less expensive : Several miles of optical cable can be made
cheaper than equivalent lengths of copper wire
Higher carrying capacity : Because optical fibers are thinner
than copper wires, more fibers can be bundled into a
given-diameter cable than copper wires
Light signals : The loss of signal in optical fiber is less than in
copper wire
Low power
Lightweight : An optical cable weighs less than a comparable
copper wire cable. Fiber-optic cables take up less space in the
ground.

6. Features of Fiber Optics
Thinner : Optical fibers can be drawn to smaller diameters
than copper wire
Light signals : Unlike electrical signals in copper wires, light
signals from one fiber do not interfere with those of other
fibers in the same cable
Digital signals : Optical fibers are ideally suited for carrying
digital information
Non-flammable : No electricity is passed through optical
fibers, there is no fire hazard
Flexible : Fiber optics are so flexible and can transmit and
receive light