Fiber optic technology uses glass or plastic fibers to transmit data using light signals. It has increased transmission capabilities allowing more information to be sent faster and over longer distances. Optical fibers are thin glass strands that carry light through the principle of total internal reflection. This occurs when light travels from a higher to lower refractive index material at an angle greater than the critical angle, causing it to reflect off the interface rather than refracting out of the fiber. Fiber optic technology has many advantages over traditional copper cables including higher bandwidth, less signal degradation over long distances, lighter weight, and immunity to electromagnetic interference.

2. Fiber
Optic
Technology

3. Contents:
Introduction
History
Construction
Principle
Working
Classifications
Application
Advantages
Disadvantages

4. Introduction:
We hear about fiber-optic cables whenever people
talk about the telephone system, the cable TV system
or the Internet.
We are increasing ability to transmit more
information, more quickly and over longer distances.
An optical fiber (or fiber) is a glass or plastic fiber
that carries light along its length . Fiber Optics is
overlap of applied science and engineering.

5. What are Fiber Optics?
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.

6. History:
1880: Alexander G. Bell
transmit sound waves over beam of light
1930: TV image through uncoated fiber cables
Few years later image through a single glass fiber
1951: Flexible fiberscope: Medical applications
1956: The term “fiber optics” used for the first time
1960: Laser invented
1967: New Communications medium: cladded fiber
1970s & 1980s : High quality sources and detectors
1990: Deployment of SONET systems

7. Construction:
Optical Fiber consists of 3 regions
1.Core – thin glass center of the
fiber where light travels.
2.Cladding – outer optical
material surrounding the core
3.Buffer Coating – plastic
coating that protects
the fiber.

8. Principle:
The principle behind the transmission of the light waves in
an Optical Fiber is “Total Internal Reflection”
The angle of refraction at the interface between two media is
governed by Snell’s law:
2211 sinsin θnθn 

9. Angle of incidence < critical angle
Angle of incidence = critical angle Angle of incidence > critical angle
Refraction, Critical angle , Total internal reflection

10. Working:
When light traveling in a dense medium hits a boundary
at a steep angle (larger than the "critical angle “for the
boundary), the light will be completely reflected. This
phenomenon is called total internal reflection.
Total internal reflection occurs when light enters from
higher refractive index to lower refractive index
material,
i. e from glass to air total internal reflection is possible
but it is not possible in air to glass.

11. In Figure
we see that where the angle 01 is greater than
the critical value the ray is refracted into the
cladding and will ultimately be lost outside the
fiber. This is loss.

12. In Figure
we see that for rays where angle01 is less than a
Critical value then the ray will propagate along
the fiber and will be “bound” within the fiber.

13. n2 cladding
n2 cladding
n1 core
Acceptance
Cone
-If the angle too large  light will be lost in cladding
- If the angle is small enough  the light reflects into
core and propagates
qC
Acceptance Cone

14. n2 cladding
n2 cladding
n1 core
Acceptance
Cone
Acceptance angle, qc, is the maximum angle in which
external light rays may strike the air/Fiber interface
and still propagate down the Fiber with <10 dB loss.
Note: n1 belongs to core and n2 refers to cladding)
2
2
2
1
1
sin nnC  
q
qC
Acceptance Angle

15. Transmission of signal:
The light in a fiber-optic
cable travels through the core
by constantly bouncing from
the cladding and the principle
called total internal
reflection.
Hence the cladding does not
absorb any light from the
core.

16. Types of Optical Fibers:
Material
used
Mode of
transmission
Refractive
index profile
Glass
Fiber
Plastic
Fiber
Single
mode
Multi
mode
Step
Index
Graded
Index

17. Classification based on “Material Used”

18. Classification based on “Modes of Transmission”

19. Classification based on “Refractive Index profile”

20. Application:
Fiber Optic Communication

21. Process of Fiber Optic Communication

22. Advantages:
Less signal degradation
Less Expensive
Lite weight
Digital Signals
Non-Flammable
Higher carrying Capacity
Thinner
Low Power
Use Light Signals

24. Disadvantages
Higher initial cost in installation
Interfacing cost
Strength
Lower tensile strength
Remote electric power
More expensive to repair/maintain
Tools: Specialized and sophisticated