optical fiber ppt presentation for the total basic concepts of optical fiber ....by A.Mallikarjuna reddy

2.  INTRODUCTION
 WHAT ARE OPTICAL FIBERS
 STRUCTURE OF OPTICAL FIBER
 WORKING PRINCIPLE OF OPTICAL FIBER
 CLASSIFICATION OF OPTICAL FIBER
 OPTICAL FIBER IN COMMUNICATION
 APPLYCATIONS OF OPTICAL FIBER
 CONCLUSION

3.  Fiber optics deals with the transformation of
information by light through fibers.
 Fiber is made up of glass , plastic or other
transparent materials.
 Light beam acting as a carrier wave is capable
of carrying more information then radio and
microwave.
 In 1870 , John dyndall observed that the
propagation of light through optical fiber.
 A single fiber can carry 140 mega byte of
information up to 220 km in one second.

5.  CORE : Central tube of very thin size made up
of optically transparent dielectric medium and
carries the light transmitter to receiver . The
core diameter can very about 5 um to 100um.
 CLADDING : Outer optical material
surrounding the core refractive index lower
than the core. It helps to keep the light within
the core throughout the phenomena of total
internal reflection.
 PLASTIC COVERING (OR) PROTECTIVE
SKIN : Plastic coating that protects the fiber
made of silicon or rubber.

6.  TOTAL INTERNAL REFLECTION
 When a ray of light travels from a denser
medium to a rarer medium such that the angle
of incidence is greater then the critical angle ,
the ray reflects back into the same medium this
phenomena is known as “ total internal
reflection”.
 In the optical fiber the rays undergo repeated
total number of reflections until it emerges out
of the other end of the fiber , even if the fiber is
bent.

8.  On the basis of number of modes of
propagation the optical fiber are classified into
two types :
 (I) Single mode fiber (SMF)
 (II) Multi mode fiber (MMF)

9.  In the single mode fiber only one mode is
propagated that type of fiber is called “ single
mode fiber”
 In the single mode optical fiber the core as a
diameter of 8-12 um and cladding as a diameter
of 125um.

10.  In the multimode fiber, fiber carriers many
hundreds of modes that type of fiber is called
as the “ multimode optical fiber”
 In the multimode fiber the core as a diameter
50 – 200 um and cladding as a diameter of 125 –
400nm.
 In the multimode fiber the light can travel in
many different paths through the core of the
fiber and can enter & live the fiber at various
angles.

12. Based on the refractive index
 Based on the variation of refractive index of
core of optical fiber . The fiber are classified
into two types .
 (I) Step index optical fiber
 (II) Graded index optical fiber

13.  In the step index optical fiber , the refractive index
of the core remains constant throughout the core
and decrease the step n1 to n2 at the cladding
interface.
 Thus , it is known as “step - index optical fiber”
 The transformation of information is in the form of
pulse (or) signals.
 Depending upon their refractive index profiles
step index fiber are characterized of two types they
are
 (I) Step index single mode fiber
 (II) Step index multimode fiber

14.  A step index single mode fiber , a single light
ray form the signal enters into the fiber and
transverses a single path and forms the output
signal.

15.  In step index multimode fiber , due to large of
core , greater no.of rays from the input singles
enters into the core and takes multi paths.
 Within the fiber axis suffers more reflections
through the fiber and takes more time to
transverse the optical fiber less no.of reflections
and with in a short time.
 It transverses the optical fiber , and the o/p end
we receive the ray(2) first and later we get ray(1).
 Due to path differences between the two light rays,
they superimpose to form the output signal.

16.  The signals are overlapped .
 In this we get signal distortion known as “inter
model dispersion”.
 It is difficult to retrieve the information carried
by the distorted output signal.

17.  In a graded index optical fiber, the core
refractive index varies continuously , that
means the refractive index of the core decreases
from the fiber axis to the classing interface in a
“parabolic” manner.

18.  The fundamental digital fiber communication
system is shown in figure.

19.  In the life of fiber is longer than copper wire
 Handling and installation costs of optical fiber
is very nominal
 It is unaffected with electromagnetic
interference.
 There is no necessity of additional equipment
for protecting against grounding and voltage
problems .

20.  Highly skilled staff would be required for
maintenance.
 Precise and costly instruments would be
required
 Costly under utilized.
 Jointing of fiber and splicing is also time
consuming.

21.  Optical fiber have wider range of applications
in almost all fields , some are been specified
below
 In telecommunication field
 In space applications
 Broadband applications
 computer applications industrial applications
 Mining applications
 In medical applications
 In military applications etc..