This document summarizes optical communication systems using fiber optic technology. It discusses the history of fiber optics from discoveries in the 1960s to modern applications. Key components of optical communication systems are described, including lasers, fibers, receivers and amplifiers. Different types of optical fibers like single mode and multi-mode are explained. Future trends in fiber optics include terabit networks and advances in component miniaturization. Fiber optic technology provides advantages like low cost, reliability and small size for applications in telecommunications, medicine, military and more.

1. OPTICAL
COMMUNICATION
SYSTEM
BY
A.AARTHI ,
B.SC (PHYSICS)

2. The field of fiber optics communications has
exploded over the past two decades.
 Fiber is an integral part of modern-day
communication .
Optical fiber is used by many telecommunications
companies to transmit telephone signals, Internet
communication, and cable television signals.
This section will provide explanations for some of
the terms associated with the field of fiber optic
engineering for telecommunications in laser.
INTRODUCTION

3. Charles K. Kao, working with George Hock ham,
made a discovery in 1966 leads to a breakthrough in
fiber optics.
 He calculated how to transmit light over long
distances via optical glass fibers, decided that, with a
fiber of purest glass, it would be possible to transmit
light signals over a distance of 100 km, compared with
only 20 m for the fiber available in the 1960s.
 In 1966 French physicist Alfred Kastler won the
Nobel Prize in physics for his method of stimulating
atoms to higher energy states. The technique, known
as optical pumping.
HISTORY

4. Fiber-optic communication is a method of
transmitting information from one place to another
by sending pulses of light through an optical fiber.
The light forms an electromagnetic carrier
wave that is modulated to carry information.
Fiber is preferred over electrical cabling when
high bandwidth, long distance, or immunity to
electromagnetic interference is required
 Another important development is that of systems
which link many different stations with a
sophisticated fiber- optic network.
OPTICAL COMMUNICATION

5. OPTICAL FIBER

6. Optical fibers are made in such a way that
optical signals undergo total internal reflection at
the boundary between the core and the cladding,
owing to the difference in the refractive indices
of the two media.
 This principle of total internal reflection is
used to trap optical signals within the core.
TRAPPING LIGHT IN A CORE
FIBER INTERNAL REFLECTION

7. Laser light is used for optical fiber
communications for the simple reason that it is a
single wavelength light source. Sunlight or the light
emitted by a light bulb is a mixture of many
different wavelengths of light.
 Because the light waves of such light are all out
of phase with one another, they do not produce a
very powerful beam.
Laser beams, however, have a single wavelength,
and so their waves are all in phase, producing very
powerful light
LASER IS THE BEST SOURCE

8. LASER BEAMS

9. Where higher level of performance is required.
Lasers have a very narrow spectral bandwidth as a
result of that fact they produce coherent light.
Laser diodes are often directly modulated.
The light output is directional and this enables a
much higher level of efficiency in the transfer of the
light into the fiber optic cable
USE OF LASER IN FIBER
OPTIC COMMUNICATION

10. Optical fiber communication systems rely on a number
of key components:
optical transmitters, based mostly on semiconductor
lasers, fiber lasers, and optical modulators.
optical receivers, mostly based on photodiodes.
optical fibers with optimized properties concerning
losses, guiding properties, dispersion,
and nonlinearities
semiconductor and fiber amplifiers for maintaining
sufficient signal powers over long lengths of fibers, or
as preamplifiers before signal detection.
KEY COMPONENTS

11. TELECOM WINDOWS
Optical fiber communications typically operate in
a wavelength region corresponding to one of the
following “telecom windows”:
 The first window at 800–900 nm was originally used .
 The first telecom window suitable only for short –
distance transmission.
The second telecom window utilizes wavelengths
around 1.3 μm.This window was originally used for
long-haul transmission.
The second and third telecom windows were originally
separated by a pronounced loss peak around 1.4 μm, but
they can effectively be joined with advanced fibers.

12. TELECOM WINDOWS

13. Optical fibers can be divided broadly into two types :
Single Mode
Multi Mode
SINGLE MODE
 single-mode fiber, has a thin core with a diameter
of about 10 μm ( 1 μm = one millionth of a meter ),
and allows light pulses to propagate in only one
mode.
Most optical fiber in use today is single-mode fiber
that enables high speed, high capacity transmission.

14. Multimode fiber, has a thick core of about 50 μm in
diameter, and permits the propagation of multiple
light pulses of differing angles of reflection.
In multimode fiber the distance at which signals can
propagate differs according to the angle of reflection,
resulting in disparities in the arrival time of signals.
MULTIMODE FIBER
MULTIMODE FIBER

15. Optical fibers have cores with diameters ranging
from 10 to 50 μm.
Optical signals are fed into the cores of these fibers
using devices known as LD (laser diode) modules.
 Laser light generated by a high-output laser diode is
passed through the lenses of the LD module to be fed
into the fiber core.
Two types of lens-an elliptical collimating lens and a
rod-shaped line generation lens-are used to focus the
laser beam and direct it towards the optical fiber core.
SENDING LIGHT BY OPTICAL
FIBER

16. SENDING LIGHT IN CORE

17. Erbium-doped fiber amplifiers (EDFAs) remain one
of the great achievements in the fiber laser technology.
The confinement of rays within the core of the fiber
preserves the intensity of the pump indefinitely along
the fiber.
The main efforts to expand the applications of the
EDFA are to include some factors, where there has been
an emphasis on the system development system
implementation.
ADVANCES IN OPTICAL FIBER
LASER

18.  Particularly, stimulating of laser amplifiers can be
achieved by distant pumping of the EDFA at around
1.47 pm.
 Fiber lasers can be constructed by semiconductors
and used as telecommunication sources owning many
advantages such as compatibility with optical fibers,
their narrow bandwidth, as well as high power output
EDFA

19. FOC is expected to continue into the future, with the
development of new and more advanced communication
technology.
Multi – Terabit Optical Networks
Intelligent Optical Transmission Network
Laser Neural Network Nodes
High – Altitude Platforms
Advancement in Network Configuration of Optical
Submarine Systems
Improvements in Glass Fiber Design and
Component Miniaturization
FUTURE TRENDS IN FIBER
OPTICS COMMUNICATION

20.  There has been a great impact made by the optical
fiber in many fields .
 This is due to inherent advantages of the optical
fibers such as low cost, small size, and ruggedness
OPTICAL FIBER TECHNOLOGY

21. APPLICATION OF FOC

22. Medical applications
Military applications
Entertainment applications
Optical Fiber Sensors
 Communications applications
At airport for communication across the runways.
Free space optical communication.
Space probes are being designed to use optical rather
than radio communication.
Laser communication has also been demonstrated on
aircraft and altitude platforms.
APPLICATIONS

23. Low cost.
Low Maintenance.
 Increased efficiency.
Reliability - Average life span of 100,000 hours.
50% smaller spot size which requires less power to
achieve the same result.
 Exceptional beam quality that is round and
concentric. No aligning of mirrors or beam path.
ADVANTAGES

24. Fiber optic is faster but delicate.
 Needs to be handled carefully during installation
and maintenance
Fragility
Difficult to Install
Attenuation & Dispersion
Cost Is Higher Than Copper Cable
DISADVANTAGES

25.  The fiber optics communications industry is an ever
evolving one, the growth experienced by the industry
has been enormous this past decade.
 There is still much work to be done to support the
need for faster data rates, advanced switching techniques
and more intelligent network architectures that can
automatically change dynamically in response to traffic
patterns and at the same time be cost efficient.
 The trend is expected to continue in the future as
breakthroughs already attained in the laboratory will be
extended to practical deployment thereby leading to a
new generation in fiber optics communications.
CONCLUSION

26. THANK
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