Prof. Z Ghassemlooy1 EN554 Photonic Networks Professor Z Ghassemlooy Northumbria Communications Laboratory School of Informatics, Engineering and Technology.

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


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


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


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.


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.


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


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


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.



• 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



• 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


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


System Evolution

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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


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


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


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


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


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

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Undersea Cables


System Block Diagram

Photonics Institute


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.


Receiver

1st-stageamplifier1st-stageamplifier

2nd-stageamplifier2nd-stageamplifier

Pre-detectionfiltering

Pre-detectionfiltering

Sampler&

detector

Sampler&

detector

DemultiplexerDemultiplexer

• Equalizer DemodulatorDemodulator

Output signalOutput signal

DecoderDecryption

DecoderDecryption


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


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


Challenges Ahead - contd.

Dedicated active and passive components Optical switches All optical regenerators Network protection Instrumentation to monitor QoS


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

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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


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

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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


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

Prof. Z Ghassemlooy1 EN554 Photonic Networks Professor Z Ghassemlooy Northumbria Communications Laboratory School of Informatics, Engineering and Technology.

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