3. Introduction
A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable,
but containing one or more optical fibers that are used to carry light. The optical fiber elements are
typically individually coated with plastic layers and contained in a protective tube suitable for the
environment where the cable is used. Different types of cable are used for different applications, for
example, long distance telecommunication, or providing a high-speed data connection between
5. Optical fiberCable
A bundle of optical fibres consists of thousands of individual
fiber wires as thin as human hair ,
Measuring 0.004mm in diameter is known as optical fiber
cable. .
6. Guidingmechanismin optical fiber
The light which enters from one end of the fiber strikes on the interface
of core and cladding at greater angle of incidence.The light beam under
goes total internal reflection and it passes along the length of the
fiber.Light travels along optical fibres.
7. Total internal reflection in optical fiber
The optical fibre obeys the laws of reflection and refraction of
light waves
A light ay travelling in a medium of refractive index nl incident
on another medium of lower refractive index n2 at the
boundary
.This light ray is reflected back in to first medium or refracted
through second medium.
The reflection or refraction of the light at the interface depends
on the difference in the speed of light in two materials having
9. • It is designed to have small refractive index difference
between the and cladding .
• The single mode fiber must be used along with laser
diodes .
• It can support only one mode of propagation
10. Multimode fiber
If more than one mode is transmtted through an optical
fiber , then the optical fiber is known as multimode fiber .
The large core radii of multimode fiber makes it easier to
launch light in to the fiber .
It can support a number of modes.
11. Single mode fiber
In single mode fiber, only one mode can propagate through the fiber
.
It has smaller core dia and the difference between the refractive
index of core and cladding is very small.
Fabrication is difficult and costly .
Multi mode fiber
Multi mode fiber allows a large number of paths or modes for the
light rays travelling through it .
.It has larger core dia and refractive index difference is larger than
the single mode fiber .
12. Optical fibers are used in military applications such
as aircrafts,ships,tanks etc. Fibers are used in
public utility organization like railways, TV
transmission etc.
Optical Fibers are used in LAN systems of offices,
industrial, plants and colleges etc.
Optical Fibers are used in telecommunication such
as voice telephones, video phones telegraph.
Optical Filters can be used under sea
