pc481 fiber optics - wilfrid laurier university course note1.pdfwdm (wavelength division...

PC481 Fiber OpticsPC481 Fiber Optics

Fall 2010Fall 2010Instructor: Dapeng ZhouInstructor: Dapeng Zhou

Lecture 1Lecture 1

Introduction to PC481

Chapter 1:Overview of Optical Fiber Communications

Introduction to PC481Introduction to PC481Course Description:Types of optical fibers. Basic theory: characteristics, numerical aperture, losses, dispersion, modes. Passive fiber devices: couplers, connectors, splices. Light sources: LED, solid and semiconductor lasers. Modulators. Detectors. Systems design. The major emphasis is on fundamentals and on individual devices which make up the system rather than on detailed design of optical communication networks.

Contents:1. Overview of optical fiber communications (Chapter 1)2. Optical fibers: structures, waveguiding, fabrication and optical cable

(Chapter 2)3. Signal degradation in optical fibers (Chapter 3)4. Optical sourses: Laser diodes and LEDs (Chapter 4)5. Power launching and coupling (Chapter 5)6. Photodetectors (Chapter 6)7. Photonic transmission systems (Chapter 7) 8. Wavelength-division multiplexing (Chapter 8)

InstructorsInstructors

Lecture instructor:Dapeng Zhou, Science Building, Room N2079(519)884-0710, ext. [email protected] hour: Fridays 13:00 pm-15:00 pm

Lab instructor:Hasan Shodiev, Science Building, Room N2086(519)884-0710, ext. [email protected]

Text BookText Book

Optical fiber communications, by Gerd Keiser, 4th edition, McGraw Hill, 2011. (The 3rd edition is no long in print; it is OK if you already have it.)

EvaluationEvaluation

Assignment: 20%Lab: 25% (At least 12.5% to pass)Midterm: 20% (End of October 2010)Final exam: 35%

Chapter 1Chapter 1Overview of Optical Fiber CommunicationsOverview of Optical Fiber Communications

OpticsOpticsOptics is an old subject involving the generation, propagation & detection of light.Optical theory development:Ray optics: short wavelength

↓

Wave optics: scalar approximation ↓

Electromagnetic optics: complete classical treatment ↓

Quantum optics: explanation of all optical phenomena

Quantum Optics

Electromagnetic OpticsWaveOptics

Ray Optics

Chapter 1 Overview of Optical Fiber CommunicationsChapter 1 Overview of Optical Fiber Communications

PhotonicsPhotonicsOptoelectronics: refers to devices & systems that are essentially electronics but involve lights, such as LED, liquid crystal displays & array photodetectors.Quantum Electronics: is used in connection with devices & systems that rely on the interaction of light with matter, such as lasers & nonlinear optical devices.Quantum Optics: Studies quantum & coherence properties of light.Lightwave Technology: describes systems & devices that are used in optical communication & signal processing.Photonics: in analogy with electronics, involves the control of photons in free space and matter.


The Scope of Photonics:The Scope of Photonics:1- Generation of Light (coherent & incoherent)

2- Transmission of Light (through free space, fibers, imaging systems, waveguides, … ) 3- Processing of Light Signals (modulation, switching,

amplification, frequency conversion, …)

4- Detection of Light (coherent & incoherent)



At sending end: Data are transferred over the communication channel by superimposing the information onto an EM wave ( known as Carrier)

At the destination, the information is removed from the carrier wave and processed as desired


Basic components of optical fiber linkBasic components of optical fiber linkOptical fibersStep/Graded-index; single-mode/multimodeSources for optical transmittersSemiconductor/fiber lasers; LEDsDetectors for optical receiversPin photodetector/Avalanche photdiodesSignal processing equipmentsModulators; multiplexer/demultiplexer; couplersOptical amplifiersErbium-doped fiber amplifier (EDFA)


Elements of an optical fiber transmission link

MilestonesMilestonesThree major developments are responsible for rejuvenation of optics & its application in modern technology:

1- Invention of Laser2- Fabrication of low-loss optical Fiber3- Development of Semiconductor

Optical Device



Evolution of fiberEvolution of fiber--optic systemsoptic systems

1950s:Imaging applications in medicine & non-destructive testing, lighting1960s:Research on lowering the fiber loss for telecom. applications.1970s:Development of low loss fibers, semiconductor light sources & photodetectors1980s:single mode fibers (OC-3 to OC-48) over repeater spacings of 40 km.1990s:Optical amplifiers (e.g. EDFA), WDM (wavelength division multiplexing) toward dense-WDM.

UnitUnitDecibels (dB) – ratios or relative unitsIn designing and implementing an optical fiber link, it is convenient to reference the signal level either to some absolutevalue or to a noise level.

Power ratio in dB =

and are optical powers in mW

2

1

10 log PP

1P 2P


UnitUnit


The dBm – absolute valueDecibel power level referred to 1 mW

Power level = 110log1

PmW

ExamplesExamples


3dB loss

200 µW in dBm unit

2

1

3 10 log( )PdBP

− =

3/102

1

10 0.5PP

−= ≈

6

3

( ) 200 1010log[ ] 10log[ ] 7.01 1 10P W WP dBmmW W

−

−

×= = = −

×


Basic fiber optic system modelBasic fiber optic system model

System performanceSystem performance

Bit Error Rate (BER)Probability of error per bitReceiver SensitivityMinimum number of photons per bit necessary to guarantee that the BER is smaller than a prescribed rateDesign StrategyAttenuation/dispersion-limited performance


WDM: wavelength-division multiplexingWDM technology: The technology of combining a number of wavelegnth onto the same fiber is known as WDM


TX1

TX2

TXn

MUX

RX1

RX2

RXn

DeMUXOA

OAOA

SMF

components for today’s typicaloptical fiber communication

TX: optical transmitter e.g. laser, modulator etc…RX: optical receiver e.g. photodiode etc…OA: optical amplifier e.g. EDFA, SOA etc…SMF: single mode fiberMUX: optical wavelength multiplexerDeMUX: optical wavelength demultiplexer

Conceptual WDM systems

Optical NetworksOptical NetworksPoint-to-point links VS Complex networks

Basic Topologies: Logical manner in which nodes are linked together

Standards (SONET/SDH) : Specify formats for optical signals so they can be shared between networks



Early application of fiber optic communicationEarly application of fiber optic communicationDigital link consisting of time-division-multiplexing (TDM) of 64 kbps voice channels (early 1980).

The fundamental building block is a 1.544 Mb/s transmission rate known as a T1 rate. At any level, a signal at the designated input rate is multiplexed with other input signals at the same rate.

Digital transmission hierarchy used in the North American telephone network


SONET & SDH StandardsSONET & SDH StandardsSONET (Synchronous Optical NETwork) is the network standard used in north America & SDH (Synchronous Digital Hierarchy) is used in other parts of the world. These define a synchronous frame structure for sending multiplexed digital traffic over fiber optic trunk lines.

The basic building block of SONET is called STS-1 (Synchronous Transport Signal) with 51.84 Mbps data rate. Higher-rate SONET signals are obtained by byte-interleaving N STS-1 frames, which are scramble & converted to an Optical Carrier Level N (OC-N) signal.

The basic building block of SDH is called STM-1 (Synchronous Transport Module) with 155.52 Mbps data rate. Higher-rate SDH signals are achieved by synchronously multiplexing N different STM-1 to form STM-N signal.


STM-649953.28STS-192OC-192

STM-324976.64STS-96OC-96

STM-162488.32STS-48OC-48

STM-81244.16STS-24OC-24

STM-4622.08STS-12OC-12

STM-1155.52STS-3OC-3

-51.84STS-1OC-1

SDH equivalentLine rate (Mb/s)Electrical levelSONET level

SONET & SDH transmission ratesSONET & SDH transmission rates

SONET multiplex hierarchySONET multiplex hierarchy

STS: Synchronous transport signalSPE: Synchronous payload envelopeVT: Virtual tributary


DWDM employmentDWDM employment


pc481 fiber optics - wilfrid laurier university course note1.pdfwdm (wavelength division...

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