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Chapter 1
INTRODUCTION OF FIBER OPTICCOMMUNICATION SYSTEMS
Fiber-Optic Communications Systems, Third Edition.
Govind P. Agrawal
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Chapter Objectives
Understand and discuss Historical Perspective: Need for Fiber
Optic Communications, Evolution of Lightwave Systems.
Describe Basic Concepts: Analog and Digital Signals, Channel
Multiplexing, Modulation Formats.
Describe Optical Communication Systems
Describe Lightwave System Components: Optical Fibers, Optical
Transmitters, Optical Receivers
Apply the basic knowledge of Optiwave Simulation Software to
determine the quality parameters of Fiber Optic Communication
Systems
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Lecture 1
Introduction to
Fiber Optic Communication Systems(1)
Understand and discuss Historical Perspective: Need for Fiber
Optic Communications, Evolution of Lightwave Systems.
Describe Basic Concepts: Analog and Digital Signals,
Channel Multiplexing, Modulation Formats.
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What is the name of this communication system?
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What is the name of this communication system?
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What is the name of this communication system?
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What is the name of this communication system?
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The Modern Communication Systems:
Microwave Communication System (Including
Mobilphone System)
Satellite Communication System
Fiber Optic Communication System
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HISTORICAL PERSPECTIVE
Up to the end of the 18th century, human used mirrors, fire
beacons, smoke signals, signaling lamps, flags, and other
semaphore devices to convey a single piece of information,
The idea was extended further, following a suggestion of
Claude Chappe in 1792, to transmit mechanically codedmessages over long distances (~100 km) by the use of
intermediate relay stations.
The first such optical telegraph was put in service between
Paris and Lille (~ 200 km apart) in July 1794. By 1830, the
network had expanded throughout Europe.
The effective bit rate of such systems: B < 1 b/s
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INTRODUCTION
HISTORICAL PERSPECTIVE
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HISTORICAL PERSPECTIVE
Need for Fiber-Optic Communications
1830s - electrical communications -Morse code (B~10b/s).
Used of intermediate relay stations allowed communication
over long distances (~1000 km)
1866 - transatlantic telegraph cable
1876 - The invention of the telephone
1940 - coaxial-cable system, 3-MHz system, transmitting 300
voice channels
1948 - First microwave system, frequency of 4 GHz (B~100Mb/s)
1975 - Coaxial system (B~274 Mb/s) repeater spacing (~1 km)
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+ To carry telephone, internet, multimedia and various broadband data
applications.
+ 18,800 kilometres long; total capacity of 1.28 Tbit/s.
+ Dense wavelength Division Multiplexing DWDM
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Need for Fiber-Optic Communications
HISTORICAL PERSPECTIVE
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HISTORICAL PERSPECTIVE
Need for Fiber-Optic Communications
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USABLE SPECTRUM OF SILICA FIBER
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2000s
Water
spike
Attenuation versus Wavelength
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Need for Fiber-Optic Communications
1970, fiber losses < 20 dB/km in the wavelength region near 1 m.
GaAs LD were demonstrated. The simultaneous availability of
compact optical sources and a low-loss optical fibers led to a
worldwide effort for developing FOCS.
The progress has indeed been rapid as evident from an increase in the
bit rate by a factor of100,000 over a period of less than 25 years.
Transmission distances have also increased from 10 to 10,000 km over
the same time period. As a result, the bit ratedistance product of modern lightwave systems
can exceed by a factor of107compared with the first-generation
lightwave systems.
HISTORICAL PERSPECTIVE
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Evolution of Lightwave Systems
HISTORICAL PERSPECTIVE
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Evolution of Lightwave Systems
The fourth generation used optical amplification for increasing
the repeater spacing and of wavelength-division multiplexing
(WDM) for enhancing the bit rate before and after 1992; bit rate
of 10Tb/s by 2001.
The fifth generation was concerned with extending the
wavelength range over which a DWDM system can operate
simultaneously (S/C/L band). The Raman amplification
technique can be used for signals in all three wavelength bands.
HISTORICAL PERSPECTIVE
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BASIC CONCEPTS
Analog an Digital Signals
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Analog an Digital Signals
BASIC CONCEPTS
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Channel Multiplexing
BASIC CONCEPTS
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Modulation Formats
BASIC CONCEPTS
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BASIC CONCEPTS
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Modulation Formats
In the case of analog modulation: AM, FM and PMThe same modulation techniques: ASK, FSK and PSK
depending on whether the amplitude, frequency, or phase of
the carrier wave is shifted between the two levels of a binary
digital signal
The simplest technique consists of simply changing the signal
power between two levels, one of which is set to zero: onoff
keying (OOK) (ASK) to reflect the onoff nature of the
resulting optical signal. Most digital lightwave systems employ
OOK in combination with PCM.
BASIC CONCEPTS
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Lecture 2
Introduction toFiber Optic Communication Systems(2)
Describe Optical Communication Systems
Describe Lightwave System Components: Optical
Fibers, Optical Transmitters, Optical Receivers
Apply the basic knowledge of Optiwave Simulation
Software to determine the quality parameters of Fiber
Optic Communication Systems
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OPTICAL COMMUNICATION SYSTEMS
Optical communication systems use high carrier frequencies (
200THz). Microwave systems use smaller carrier frequency (20 GHz).
An increase in the information capacity of optical communication
systems by a factor of up to 10,000 is expected simply because of
such high carrier frequencies used for lightwave systems.
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Typical Fiber Optic communication systems
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Some of typical equipments in FOCS
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LIGHTWAVE SYSTEM COMPONENTS
Optical Fibers as a Communication Channel
o Most lightwave systems use optical fibers as the
communication channel because silica fibers can transmit
light with losses as small as 0.2 dB/km. Optical power
reduces to only 1% after 100 km
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Fundamental limits of silica fibers
C-band: supports early EDFA
C+L-band: support for EDFAs of today
Raman amplifiers can be used over all bands - new
(medium loss) bands are now applicable (as S & U
bands)
New fibers can reduce loss at E & S bands (however,
EDFA does not work here & Raman gain small)
O-band Original 1260-1360
E-band Extended 1360-1460
S-band Short 1460-1530
C-band Conventional 1530-1565
L-band Long 1565-1625
U-band Ultra-long 1625-1675
Band Description Wavelength (nm)
Inter- and Intra-modal dispersion
Attenuation (Loss)
Non-linear effects
Four-wave mixing (FWM)
Stimulated Raman & Brillouin
scattering (SRS,SBS)
Cross-phase & self-phase modulation (SPM,XPM
Polarization fluctuations
0.8 1.0 1.2 1.4 1.6 1.8
Wavelength (mm)
Water spike
Rayleigh scattering
Infrared absorption
Loss(dB/km)
100
50
10
1
0.5
0.1
5
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ADVANTAGES OF OPTICAL COMMUNICATIONS
1. Enormous Bandwidths. 2. Low transmission loss .
3. Immunity to cross talk
4. Electrical Isolation
5. Small size and weight 6. Signal security
7. Flexibility
8. Low cost and availability
9. ReliabilityThe lightwave technology, together with microelectronics, is
believed to be a major factor in the information age.
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ADVANTAGES OF OPTICAL COMMUNICATIONS
5. Small size and weight
ADVANTAGES OF OPTICAL COMMUNICATIONS
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ADVANTAGES OF OPTICAL COMMUNICATIONS
5. Small size and weight
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Introduction on Optiwave Simulation Software
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Project Structure
OptiSystem Graphical User Interface
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OptiSystem Graphical User Interface
Placing Components in the Main Layout
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Placing Components in the Main Layout
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Lab 1 - Determining critical parameters of Fiber
Optic Communication system
Setting the working parameters for FOCS
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Setting the working parameters for FOCS
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Laser Spectrum
Spectrum at the Laser output and at the PhotoDiode input
Optical powers at the Modulator output
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Optical powers at the Modulator output
and at the Photodiode input
The quality parameters: BER Q of FOCS
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The quality parameters: BER, Q of FOCS