prof. z ghassemlooy1 en554 photonic networks professor z ghassemlooy northumbria communications...
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1Prof. Z Ghassemlooy
EN554 Photonic Networks
Professor Z Ghassemlooy
Northumbria Communications LaboratorySchool of Informatics, Engineering and
TechnologyThe University of Northumbria
U.K.http://soe.unn.ac.uk/ocr
Lecture 1: Introduction
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Contents Reading List Lecture 1: Introduction
Transmission Media History Communication Technologies Applications System Challenges Ahead
Lecture 2: Components for Photonic Networks Lecture 3: Optical Amplifier Lecture 4: System Limitation and Non-linear effect Lecture 5: Transmission System Engineering Part 1 Lecture 6: Transmission System Engineering Part 2 Lecture 7: Photonic Networks Lecture 8: Photonic Switching Lecture 9: Wavelength Routing Networks Part 1 Lecture 10: Wavelength Routing Networks Part 2 Lecture 11: Access Network Lecture 12: Revision Tutorials and Solutions: Visit http://soe.unn.ac.uk/ocr
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Reading List
Essential Reading List– lyas, Mohammad and Mouftah, Hussien: The Handbook of Optical
Communication Networks, CRC Press, 2004, ISBN 0-84-931333-3– Ramasawami, R and Sivarajan, K.N: Optical network: A practical
perspective, Morgan Kaufmann, 2001, ISBN 1-55-860655-6– Donati, Silvano: Photodetectors: Devices, Circuits and
Applications, Prentice Hall, 2000, ISBN 0-13-020337-8
Optional Reading List– Stern, T.E. and Bala, K: Multiwavelength Optical Networks: A
layered approach, Addison Wesley, 1999, ISBN 0-20-130967-X– Sabella, R and Lugli, P:High speed optical communications,
Kluwer Academic, 1999, ISBN 0-41-280220-1
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Transmission Media
Transmission Medium, or channel, is the actual physical path that data follows from the transmitter to the receiver.
Copper cable is the oldest, cheapest, and the most common form of transmission medium to date.
Optical Fiber is being used increasingly for high-speed applications.
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Transmission by Light: why?
Growing demand for faster and more efficient communication systems
Internet traffic is tripling each year It enables the provision of Ultra-high bandwidth to
meet the growing demand Increased transmission length Improved performance etc.
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Demand for Bandwidth
BandwidthDemand
1990 2000 2010
• Raw text = 0.0017 Mb• Word document = 0.023 Mb• Word document with picture = 0.12 Mb• Radio-quality sound = 0.43 Mb• Low-grade desktop video = 2.6 Mb• CD-quality sound = 17 Mb• Good compressed (MPEG1) video = 38 Mb
Typical data bandwidth requirement
20,000 x
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Historical Developments
• 800 BC Use of fire signal by the Greeks• 400 BC Fire relay technique to increase transmission distance• 150 BC Encoded message• 1880 Invention of the photophone by Alexander Graham Bell
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Historical Developments - contd.
• 1930 Experiments with silica fibres, by Lamb (Germany)• 1950-55 The birth of clad optical fibre, Kapany et al (USA)• 1962 The semiconductor laser, by Natan, Holynal et al (USA)• 1960 Line of sight optical transmission using laser:
- Beam diameter: 5 m - Temperature change will effect the laser beam
Therefore, not a viable option
•1966- A paper by C K Kao and Hockham (UL) was a break through
- Loss < 20 dB/km - Glass fibre rather than crystal (because of high viscosity) - Strength: 14000 kg /m2.
Contd.
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Historical Developments - contd.
• 1970 Low attenuation fibre, by Apron and Keck (USA) from 1000 dB/km - to - 20 dB/km - Dopent added to the silica to in/decrease fibre refractive index.• Late 1976 Japan, Graded index multi-mode fibre - Bandwidth: 20 GHz, but only 2 GHz/km
Start of fibre deployment.
• 1976 800 nm Graded multimode fibre @ 2 Gbps/km.• 1980’s - 1300 nm Single mode fibre @ 100 Gbps/km - 1500 nm Single mode fibre @ 1000 Gbps/km
- Erbium Doped Fibre Amplifier
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Historical Developments - contd.
• 1990’s - Soliton transmission (exp.): 10 Gbps over 106 km with no error - Optical amplifiers - Wavelength division multiplexing, - Optical time division multiplexing (experimental) OTDM
• 2000 and beyond- Optical Networking - Dense WDM, @ 40 Gbps/channel, 10 channels
- Hybrid DWDM/OTDM ~ 50 THz transmission window > 1000 Channels WDM > 100 Gbps OTDM Polarisation multiplexing
- Intelligent networks
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Lightwave Evolution
Single Channel (ETDM)Multi-Channel (WDM)Single Channel (OTDM)WDM + OTDMWDM + Polarization Mux *Soliton WDM
Cap
acit
y (G
b/s
)
10,000
300
100
30
10
3
1
0.3
0.1
0.03
1000
3000
84 86 88 90
Year92 94 96 9880 82
*
00 02
*
04
SystemsResearchExperiments
Courtesy:A. Chraplyvy
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System Evolution
cisco
FiberizationDigitization
SONET rings and DWDM linear systems
Optical networkingWavelength SwitchingTOTDM
Research Systems
Commercial Systems
0.1
1
10
100
1000
10000
1985 1990 1995 2000
Year
Cap
acit
y (G
b/s
)
2004
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Existing Systems - 1.2 Tbps WDM
• Typical bit rate 40 Gbps / channel• ~ 8 THz (or 60 nm) Amplifier bandwidth• 32 channels (commercial) with 0.4 nm (50 GHz) spacing• 2400 km, no regeneration (Alcatel)
Total bandwidth = (Number of channels) x (bit-rate/channel)
DWDMDWDM
OTDMOTDM
• Typical bit rate 6.3 Gbps / channel• ~ 400 Amplifier bandwidth• 16 channels with 1 ps pulse width
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Commercial Systems
H. Kogelnik, ECOC 2004
System Year WDM chan -nels
Bit rate/ channel
Bit rate/ Fibre
Voice channels per fibre
Regen spans
FT3 1980 1 45 Mb/s 45 Mb/s 672 7 km
FTG -1.7 1987 1 1.7
Gb/s 1.7 Gb/s 24,192 50 km
FT-2000 1992 1 2.5
Gb/s 2.5 Gb/s 32,256 50 km
NGLN 1995 8 2.5
Gb/s 20 Gb/s 258,000 360 km
WaveStar TM 400G
1999 80 40
2.5 Gb/s
10 Gb/s
200 Gb/s 400 Gb/s
2,580,000 5,160,000
640 km 640 km
WaveStar TM 1.6T
2001 160 10 Gb/s 1.6 Tb/s 20,640,000 640 km
LambdaXtreme 2003 128 64
10 Gb/s 40 Gb/s
1.28 Tb/s 2.56 Tb/s
16,512,000 33,0 24,000
4000 km 1000 km
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Communications Technologies
Year Service Bandwidth distance product
1900 Open wire telegraph 500 Hz-km
1940 Coaxial cable 60 kHz-km
1950 Microwave 400 kHz-km
1976 Optical fibre 700 MHz-km
1993 Erbium doped fibre amplifier 1 GHz-km
1998 EDFA + DWDM > 20 GHz-km
2001- EDFA + DWDM > 80 GHz-km
2001- OTDM > 100 GHz-km
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Optical Technology - Advantages
• High data rate, low transmission loss and low bit error rates• High immunity from electromagnetic interference• Bi-directional signal transmission• High temperature capability, and high reliability• Avoidance of ground loop• Electrical isolation• Signal security• Small size, light weight, and stronger
448 copper pairs5500 kg/km
62 mm
21mm
648 optical fibres363 kg/km
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Applications
Optical Communication Systems High Speed Long Haul Networks (Challenges are transmission type)
Metropolitan Area Network (MAN) ? Access Network (AN)? Challenges are:
- Protocol - Multi-service capability - Cost
Electronics and Computers Broad Optoelectronic Medical Application Instrumentation
Optics
is he
re to
stay
for
a lon
g tim
e.
Optics
is he
re to
stay
for
a lon
g tim
e.
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Undersea Cables
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System Block Diagram
Photonics Institute
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Source
SourcecodingSourcecoding
ModulationModulation MultiplexingMultiplexing ModulationModulation
ExternalExternal InternalInternal
• Analogue• Digital• Analogue• Digital
• Frequency• Time• Frequency• Time
• Pulse shaping• Channel coding• Encryption• etc.
• Pulse shaping• Channel coding• Encryption• etc.
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Receiver
1st-stageamplifier1st-stageamplifier
2nd-stageamplifier2nd-stageamplifier
Pre-detectionfiltering
Pre-detectionfiltering
Sampler&
detector
Sampler&
detector
DemultiplexerDemultiplexer
• Equalizer DemodulatorDemodulator
Output signalOutput signal
DecoderDecryption
DecoderDecryption
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All Optical Network
SDHSDH
ATMATM
IPIP
SDHSDH
ATMATM
IPIP
Open Optical InterfaceOpen Optical Interface
SDHSDH ATMATM IPIP OtherOther
All Optical Networks
Challenges ahead:
• Network routing• Network routing • True IP-over-optics• True IP-over-optics• Network protection• Network protection
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Challenges Ahead
Modulation and detection and associated high speed electronics Multiplexer and demultiplexer Fibre impairments: . Loss . Chromatic dispersion . Polarization mode dispersion . Optical non-linearity . etc.
Optical amplifier . Low noise . High power . Wide bandwidth. Longer wavelength band S
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Challenges Ahead - contd.
Dedicated active and passive components Optical switches All optical regenerators Network protection Instrumentation to monitor QoS
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Chromatic Dispersion
60 Km SMF-28
4 Km SMF-28
10 Gbps
40 Gbps
t
t
• It causes pulse distortion, pulse "smearing" effects
• Higher bit-rates and shorter pulses are less robust to Chromatic Dispersion
• Limits "how fast“ and “how far” data can travel
cisco
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Dispersion Compensating Fibre
By joining fibres with CD of opposite signs (polarity) and suitable lengths an average dispersion close to zero can be obtained; the compensating fiber can be several kilometers and the reel can be inserted at any point in the link, at the receiver or at the transmitter
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Polarization Mode Dispersion (PMD)
The optical pulse tends to broaden as it travels down the fibre; this is a much weaker phenomenon than chromatic dispersion and it is of some relevance at bit rates of 10Gb/s or more
nx
nyEx
Ey
Input pulse Spreaded output pulse
cisco
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Combating PMD
Factors contributing to PMD– Bit Rate– Fiber core symmetry– Environmental factors– Bends/stress in fiber– Imperfections in fiber
Solutions for PMD– Improved fibers – Regeneration– Follow manufacturer’s recommended installation
techniques for the fiber cable
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Optical Transport Network
Global Network
Wide Area Network
Metropolitan/Regional Area Optical Network
Corporate/Enterprise Clients
Cable modemNetworks
Client/Access Networks
FTTHMobile
SDH/SONET
ATM
PSTN/IP
ISPGigabit Ethernet
Cable
FTTB
ATM
< 10000 km< 10 Tbit/s
< 100 km< 1 Tbit/s
< 20 km100M - 10 Gbit/s
Courtesy: A.M.J. Koonen