optical interconnect and sensing detection and transmission · optical fiber an optical fiber is a...

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Optical Interconnect and Optical Interconnect and SensingSensing

Dr. How T. LinDr. How T. LinEndicott Interconnect Endicott Interconnect

TechnologiesTechnologies

TopicsTopics

•• Light FundamentalsLight Fundamentals•• Common Optical Components for Light Emission and Common Optical Components for Light Emission and

Detection and TransmissionDetection and Transmission•• Optical Interconnect PrincipleOptical Interconnect Principle•• Optical InterconnectsOptical Interconnects

•• Fiber OpticsFiber Optics•• Optical WaveguidesOptical Waveguides

•• Optical Sensing with FBG (Fiber Bragg Grating Sensing)Optical Sensing with FBG (Fiber Bragg Grating Sensing)•• PrinciplePrinciple•• ApplicationsApplications

Disadvantages of Electrical Disadvantages of Electrical Interconnects/SensorsInterconnects/Sensors

•• Physical Problems (at high frequencies/high Physical Problems (at high frequencies/high noise environments)noise environments)

CrossCross--talktalkSignal DistortionSignal DistortionElectromagnetic InterferenceElectromagnetic InterferenceReflectionsReflectionsHigh Power ConsumptionHigh Power ConsumptionHigh Latency (RC Delay)High Latency (RC Delay)Limited BandwidthLimited Bandwidth

Why Optics ?Why Optics ?•• Advantages:Advantages:

Capable to provide high bandwidthsCapable to provide high bandwidthsFree from electrical shortFree from electrical short--circuitscircuitsLowLow--loss transmission at high frequenciesloss transmission at high frequenciesImmune to electromagnetic interferenceImmune to electromagnetic interferenceEssentially no crosstalk between adjacent signalsEssentially no crosstalk between adjacent signalsNo impedance matching requiredNo impedance matching required

•• Successful longSuccessful long--haul telecommunication system based haul telecommunication system based on fiber opticson fiber optics

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Using Lightwave to Transmit Using Lightwave to Transmit InformationInformation

Simplified phasor representation of EM wave

E(t) cos(ωt+θ)

Amplitude frequency phase

Device a method to detect change in any one of the three variables listed above……….we have a data transmitter!

Optical Interconnect FundamentalsOptical Interconnect Fundamentals

λ1 λ1

Basic Optical Interconnect

Transmitter Transmission Medium Receiver

Transmitter: LED or Laser

Transmission Medium: Fiber optics (MM/SM), Polymer Waveguide or Free Space

Receiver: Photo Diode or Transistor

EM Spectrum EM Spectrum EM Spectrum (Visible)EM Spectrum (Visible)

UV…..……………..Visible…………………IR

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What is Light?What is Light?RaysWavesParticles

AbsorptionEmission

Interference RefractionReflection

Bandgap

Conduction band

Valence band

n0

n1

n0

A little Quantum TheoryA little Quantum Theory•• Definition:Definition:

•• Optical powerOptical power watt (W) watt (W) -- a rate of energy of one a rate of energy of one joule (J) per second.joule (J) per second.

•• Optical power is a function of both the number of Optical power is a function of both the number of photons and the wavelength. Each photon carries photons and the wavelength. Each photon carries an energy that is described by Planckan energy that is described by Planck’’s equation: s equation: Q = Q = hchc //λλwhere where Q= photon energy in JQ= photon energy in J

h = Planckh = Planck’’s constant (6.623 x 10s constant (6.623 x 10--3434 Js)Js)c = speed of light (2.998 X x 10c = speed of light (2.998 X x 108 8 m/sm/s))λλ = wavelength in meters= wavelength in meters

Basic Optical PrinciplesBasic Optical Principles

•• Optical FilterOptical Filter ::•• Absorption by filter glass varies Absorption by filter glass varies

with with λλ and thickness (d) of and thickness (d) of substratesubstrate

•• At each interface, part of the At each interface, part of the incident light will be reflected incident light will be reflected and the rest will pass throughand the rest will pass through..

•• Interface LossesInterface Losses ::•• FresnelFresnel’’s Law s Law

rrλλ = reflection loss (normal = reflection loss (normal incidence)incidence)

nnλλ = = nn’’/n/n

rrλλ = = nnλλ --1/ 1/ nnλλ +1+1

Transmission through an optical filter

Interface Losses


•• RefractionRefraction ::SnellSnell’’s Law s Law ––

n sin(n sin(θθ) = n) = n’’ sin(sin(θθ’’))Index of refraction: Index of refraction: n = 1.0 for airn = 1.0 for air

n = 1.5 for glassn = 1.5 for glass

Transmission through an optical filter

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•• DiffractionDiffraction::•• Lightwave bends when pass by small apertureLightwave bends when pass by small aperture

θ = λ/θ = λ/DDwherewhere θ θ is the diffraction angleis the diffraction angle

λλ is the wavelengthis the wavelengthD is the aperture widthD is the aperture width

D


•• InterferenceInterference::•• Wave nature of light causes interference patterns:Wave nature of light causes interference patterns:

Interference filter for wavelength selection Interference filter for wavelength selection --


•• CollimationCollimation::•• Place point source at focal point of lens or parabolic mirror Place point source at focal point of lens or parabolic mirror

can produce collimated light (parallel light beam)can produce collimated light (parallel light beam)

Collimation with lens and parabolic mirror

Slit

•• Wavelength Selection:Wavelength Selection:•• Prisms:Prisms:

•• with high n, select with high n, select λλ with with narrow slitnarrow slit

•• Gratings:Gratings:•• disperse light into disperse light into

spectrum with ruled linesspectrum with ruled lineswhere m is an integer where m is an integer (order)(order)


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•• LasersLasers•• GasGas•• LiquidLiquid•• Solid StateSolid State•• Semiconductor (diodes)Semiconductor (diodes)

•• Light Emitting Diodes (LED)Light Emitting Diodes (LED)

Light SourcesLight Sources•• Lasers Lasers

((LLight ight AAmplification by mplification by SStimulated timulated EEmission of mission of RRadiation)adiation)•• GasGas•• Solid StateSolid State•• LiquidLiquid•• Semiconductor (diode)Semiconductor (diode)Characteristics: Characteristics: •• CoherenceCoherence -- Photons have fixed phase relationship.Photons have fixed phase relationship.•• Relative narrow spectraRelative narrow spectra•• Low divergence after collimation.Low divergence after collimation.•• Difficult to modulate (gas, liquid).Difficult to modulate (gas, liquid).•• High cost.High cost.

•• LEDLED((LLight ight EEmitting mitting DDiodes)iodes)Characteristics:Characteristics:•• Incoherence Incoherence --Photons with random phasePhotons with random phase•• Relative broad spectra.Relative broad spectra.•• Low cost.Low cost.•• Easy modulation.Easy modulation.•• Small sizeSmall size

Light Sources Light Sources

Light Sources : Semiconductor LasersLight Sources : Semiconductor Lasers

active

n-DBR

p-DBR

VCSEL

Light Sources : Light Sources : LEDsLEDs

Edge emitting LED

Surface emitting LED

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Light DetectionLight Detection•• Two broad classes of optical detectors:Two broad classes of optical detectors:

•• Photon detectors Photon detectors –– interactions of quanta of light energy with electrons in interactions of quanta of light energy with electrons in the detector material and generating free electrons (wavelength the detector material and generating free electrons (wavelength dependent).dependent).

•• Thermal detectors Thermal detectors -- respond to the heat energy delivered by the light respond to the heat energy delivered by the light (wavelength independent).(wavelength independent).

Light DetectionLight Detection•• Photon detectors:Photon detectors:

•• PhotoemissivePhotoemissive. These detectors use the photoelectric effect, in . These detectors use the photoelectric effect, in which incident photons free electrons from the surface of the which incident photons free electrons from the surface of the detector material. These devices include vacuum photodiodes, detector material. These devices include vacuum photodiodes, CCD camera, bipolar phototubes, and photomultiplier tubes.CCD camera, bipolar phototubes, and photomultiplier tubes.

•• Photoconductive. The electrical conductivity of the material Photoconductive. The electrical conductivity of the material changes as a function of the intensity of the incident light. changes as a function of the intensity of the incident light. Photoconductive detectors are semiconductor materials. They Photoconductive detectors are semiconductor materials. They have an external electrical bias voltage.have an external electrical bias voltage.

•• Photovoltaic. These detectors contain a Photovoltaic. These detectors contain a pp--nn semiconductor semiconductor junction and are often called photodiodes. A voltage is self junction and are often called photodiodes. A voltage is self generated as radiant energy strikes the device. The photovoltaicgenerated as radiant energy strikes the device. The photovoltaicdetector may operate without external bias voltage. A good detector may operate without external bias voltage. A good example is the solar cell used on spacecraft and satellites to example is the solar cell used on spacecraft and satellites to convert the sunconvert the sun’’s light into useful electrical power.s light into useful electrical power.

Photoconductive and photovoltaic detectors are commonly used in Photoconductive and photovoltaic detectors are commonly used in circuits in which circuits in which there is a load resistance in series with the detector. The outpthere is a load resistance in series with the detector. The output is read as a ut is read as a change in the voltage drop across the resistorchange in the voltage drop across the resistor..

Light Detection : Detector characteristicsLight Detection : Detector characteristics•Responsivity - Defined as the detector output per unit of input power.

The units of responsivity are either amperes/watt (alternatively milliamperes/milliwatt or microamperes/microwatt.

•Quantum efficiency – Defined as the effectiveness of the incident radiant energy for producing electrical current in a circuit. It may be related to the responsivity by the equation:

Q = 100 x Rd x hv = 100 x Rd (1.2395/λ ).

•Noise equivalent power (NEP) - Defined as the radiant power that produces a signal voltage (current) equal to the noise voltage (current) of the detector.

NEP = IAVN / VS(∆ f)1/2where I is the irradiance incident on the detector of area A, VN is the root mean square noise voltage within the measurement bandwidth ∆ f, and VS is the root mean square signal voltage.

Light DetectionLight Detection

•• Materials Materials ––•• Silicon (Si)Silicon (Si)

•• Least expensiveLeast expensive

•• Germanium (Germanium (GeGe))•• ““ClassicClassic”” detectordetector

•• Indium gallium Indium gallium arsenide (InGaAs)arsenide (InGaAs)

•• Highest speedHighest speed

Res

pons

ivity

(A/W

)

Wavelength nm500 1000 1500

Silicon

Germanium

InGaAs

Quantum Efficiency = 1

0.1

0.5

1.0

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Optical Fiber

Professor Charles Kao who has been recognized as the inventor of fiber optics is receiving an IEE prize from Professor John Midwinter (1998 at IEE Savoy Place, London, UK; courtesy of IEE)

Optical Fiber An optical fiber is a flexible filament of very clear glass and is capable of carrying information in the form of light. This filament of glass is a little thicker than a human hair.

Dielectric Waveguides and Optical FibersStep Index Fiber

Optical fiber structure

• The difference in refractive index between the core and cladding is < 0.5%.• The refractive index of the core is higher than that of the cladding, so that

light in the core strikes the interface with the cladding at a bouncing angle and is trapped in the core by total internal reflection.

The cladding is the layer completely surrounding the core.

The core, or the axial part of the optical fiber, is the light transmission area of the fiber.

• A mode is a defined path in which light travels.

• A light signal can propagate through the core of the optical fiber on a single path (single-mode fiber) or on many paths (multimode fiber). The mode in which light travels depends on geometry, the index profile of the fiber, and the wavelength of the light.

• Single-mode fiber has the advantage of high information-carrying capacity, low attenuation and low fiber cost, but multimode fiber has the advantage of low connection and electronics cost that may lead to lower system cost.

Dielectric Waveguides and Optical Fibers

• Multimode vs. Single-mode

Step Index Fiber• Schematic diagram of Step Index Fiber

n

y

n2 n1

Cladding

Core z

y

rφ

Fiber axis

Normalized index difference

1

21

nnn −

=∆

Typically∆

8

n1

n2

21

3

nO

n1

21

3

n

n2

OO' O''

n2

Multimode Step Index Fiber Ray paths are different so thatrays arrive at different times.

Graded Index Fiber

Ray paths are different but so are the velocities along the paths so that all the rays arrive at the same time.

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The Graded Index (GRIN) Optical Fiber

n decreases step by step from one layer to next upper layer; very thin layers.

n decrease in continuous gives a ray path changing continuously.

TIR

A ray in thinly stratified medium becomes refracted as it passes from one layer to the next upper layer with lower nand eventually its angle satisfies TIR.

In a medium where n decreases continuously the path of the ray bends continuously.

The Graded Index (GRIN) Optical Fiber

TIR

Light Absorption and Scattering• Attenuation

• The reduction in signal strength is measured as attenuation.

• Attenuation measurements are made in decibels (dB). The decibel is a logarithmic unit that indicates the ratio of output power to input power.

• Each optical fiber has a characteristic attenuation that is normally measured in decibels per kilometer (dB/km).

• Optical fibers are distinctive in that they allow high-speed transmission with low attenuation.

kz

E Medium

( fib b di )

Attenuation = Absorption Scattering+ Extrinsic factor +

Light Absorption and Scattering• Absorption

• Lattice absorption through a crystal

z

A solid with ions

Light direction

k

Ex

• The field in the wave oscillates the ions which consequently generate "mechanical“ waves in the crystal; energy is thereby transferred from the wave to lattice vibrations.

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Scattered waves

Incident wave Through wave

A dielectric particle smaller than wavelength

• Rayleigh scattering involves the polarization of a small dielectric particle or a region that is much smaller than the light wavelength.

• The field forces dipole oscillations in the particle (by polarizing it) which leads to the emission of EM waves in "many" directions so that a portion of the light energy is directed away from the incident beam.

• Rayleigh scattering

Displacing electron with respect to positive nuclei.

Oscillating charge = Alternating current

Radiates EM waves

Light Absorption and Scattering Attenuation in Optical Fibers

• Optical Fiber Attenuation vs. wavelength

Fiber LossFiber Loss

Attenuation in Optical Fibers

• Attenuation vs. wavelength

Stretching of Si-O bonds in ionic polarization induced by EM wave, which is around 9 µm.

Stretching of Si-O bonds in ionic polarization induced by EM wave, which is around 9 µm. Presence of hydroxyl ions (water) as

an impurity.Stretching vibration of OH- bonds at 2.7 µm. Its overtones at 1.0 & 1.4 µm.

combinationof Si-O & 1.4 µm

• Micro-bending loss

Attenuation in Optical Fibers

• Sharp bends change the local waveguide geometry that can lead to waves escaping.• The zigzagging ray suddenly finds itself with an incident angle θ’ that gives rise to either a

transmitted wave, or to greater cladding penetration; the field reaches the outside medium and some light energy is lost.

Escaping wave

θ θ

θ′ < θ

θθ > θc θ′

Microbending

R

Cladding

Core

Field distribution

• Small changes in the refractive index of the fiber due to induced strains when it is bent during its use, e.g., when it is cabled and laid.

• Induced strains change n1 and n2, and hence affect the mode field diameter, that is field penetration into the cladding.

• Macrobending loss crosses over into microbending loss when the radius of curvature becomes less than a few centimeters.

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Fiber Fabrication

• Fiber Materials Glasses and Plastics• It must be possible to make long, thin flexible fibers from the materials.• The material must be transparent at a particular optical wavelength in order

for the fiber to guide light efficiently.• Physically compatible materials that have slightly different refractive

indices for the core and cladding must be available• Silica Glass Fibers

• Glass do not have well defined melting point. The glass become to soften at high temperature (>1000°C), it became viscous liquid.

• SiO2:GeO2 core; SiO2 claddingSiO2:P2O5 core; SiO2 claddingSiO2 core; SiO2:B2O3 claddingSiO2:GeO2/B2O3 core; SiO2:B2O3 cladding

Dopant addition (mol %)

Ref

ract

ive

inde

x

1.46

1.48

1.44 5 10 15 20

GeO2

P2O5

B2O3

SiO2 @ 850 nm

Fiber materials

• Halide Glass Fibers

• Active Glass Fibers

• Chalgenide Glass Fibers

• Plastic Optical Fibers: POF• Short distance (∼100 m), very flexible, relaxation of connector tolerance, low cost• polymethylmethacrylate (PMMA) or perifluorinated polymer (PFP)

• High non-linearity optical properties for all optical switch or fiber lasers• Chalcogen elements are doped: S, Se, Te…

• Amplification, Attenuation, Phase retardation• Rare earth elements are doped (0.005-0.05 mole%): atomic no. 57-71, Er, Pr…

• Extremely low transmission losses at mid-IR (@0.2∼8 µm) 0.01∼0.001 dB/km)• ZrF4, BaF2, LaF3, AlF3, NaF• Fabricating long lengths of fibers is difficult.

• Outside Vapor-Phase Oxidization

• Vapor-Phase Axial Deposition

• Modified Chemical Vapor Deposition• Plasma-Activated Chemical Vapor Deposition

• Double-Crucible Method

• Fiber Fabrication

Fiber Fabrication• Schematic illustration of a fiber drawing tower.

Fiber Drawing

Preform feed

Furnace 2000°C

Thicknessmonitoring gauge

Take-up drum

Polymer coater

Ultraviolet light or furnacefor curing

Capstan

Pref

orm

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Vapors: SiCl4+ GeCl4+ O2

Rotate mandrel

(a)

Deposited sootBurner

Fuel: H2

Target rod

Deposited Ge doped SiO2

(b)

Furnace

Porous sootpreform with hole

Clear solidglass preform

Drying gases

(c)

Furnace

Drawn fiber

Preform

Reaction of gases in the burner flame produces glass soot that deposits on to the outside surface of the mandrel.

The mandrel is removed and the hollow porous soot preform is consolidated; the soot particles are sintered, fused, together to form a clear glass rod.

The consolidated glass rod is used as a preform in fiber drawing.

Outside Vapor Deposition (OVD)

• Schematic illustration of OVD and the preform preparation for fiber drawing

SiCl4 (gas) + O2 (gas) SiO2 (solid) + 2Cl2 (gas)GeCl4 (gas) + O2 (gas) GeO2 (solid) + 2Cl2 (gas)

Outside Vapor Deposition (OVD)

The soot rod fed into the consolidation furnace for sintering.

Glass preform fed into the fiber drawing furnace

Optical CablesOptical Cables

•• Single mode and MultimodeSingle mode and Multimode•• Single fiber and Fiber arraysSingle fiber and Fiber arrays•• Polished facePolished face•• Strain reliefStrain relief•• Parameters: Insertion Loss, Attenuation, Parameters: Insertion Loss, Attenuation,

min bend radius, Face anglemin bend radius, Face angle•• ExpensiveExpensive

Single FiberSingle Fiber

SC - MultimodeST - MultimodeDuplex LC

FC – Single mode MU – Single Mode E2000 Multimode

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Fiber ArraysFiber Arrays

MTP test from Mipox

Multilayer ArraysMultilayer Arrays

XMP from Xanoptix

Polymer Optical WaveguidesPolymer Optical Waveguides

•• Requirements:Requirements:•• Compatible with standard PWB TechnologiesCompatible with standard PWB Technologies•• High performance (low optical loss)High performance (low optical loss)•• Robust (>230 degrees C, >10 sec.)Robust (>230 degrees C, >10 sec.)•• Dense (

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•• Processing StepsProcessing Steps

Polymer Optical WaveguidesPolymer Optical Waveguides Polymer Optical WaveguidesPolymer Optical WaveguidesSamples

http://matlib.kjst.ac.kr/~optoelec/research/waveguide/p-waveguide.html

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Optical Backplanes Speed Data Optical Backplanes Speed Data

In DaimlerChrysler's optical backplane, the beam from a laser diode passes through one set of lenses and reflects off a micromirror before reaching a polymer waveguide, then does the converse before arriving at a photodiode and changing back into an electrical signal. A prototype operates at 1 Gb/s.

FreeFree--Space Interconnects Pack in Space Interconnects Pack in Data Channels Data Channels

An experimental module from the University of California, San Diego, just 2 cm high, connects stacks of CMOS chips. Each stack is topped with an optics chip [below center] consisting of 256 lasers (VCSELs) and photodiodes. Light from the VCSELs makes a vertical exit from one stack [below, left] and a vertical entry into the other. In between it is redirected via a diffraction grating, lenses, an alignment mirror [center], and another grating. Each of the device's 256 channels operates at 1 Gb/s.

Optical SensingOptical SensingTypical sensing system configuration using photons

Light source

Optical detector

Optional optical detector

Ambient (light): noise source

Ambient (light): noise source

Electronics

Subject of interest

sign

al +

noi

se Operating medium

Photon Sensing System IssuesPhoton Sensing System Issues

• Selection of Light Sources• Selection Light Detectors• Minimizing effect of background noise

resulting from ambient light sources• System Performance

• Resolution• Speed• Accuracy

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Fiber Optics For Measurement ApplicationsFiber Optics For Measurement ApplicationsTemperature Measurement Example:Technology - Light absorption/transmission properties of gallium

arsenide (GaAs)

Fiber

Semiconductor Crystal

Dielectric Mirror

Teflon

Technology - Fluoresence-decay of phosphor.

Temp. λabs

λabs = f(T)

Fiber Optic Temperature Probe

Fiber Mirror

Jacket

Timedecay = f(temp.) Fiber Optic Temperature Probe

Phosphor

Light

Light

Fiber Optics For Measurement ApplicationsFiber Optics For Measurement Applications

Fiber Optic Chemical Sensors (FOCS):

Fiber Dielectric

Mirror

TeflonChemical

Cladding removed substituted by suitable chemical

Light

Escape light

Amount of light loss is proportional to the amount of chemical present

FBG (Fiber Bragg Grating)FBG (Fiber Bragg Grating) _FBG (Fiber Bragg Grating)FBG (Fiber Bragg Grating)

λλ

λI

I I

Λ= Grating Period

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Operation Principle of FBG SensorOperation Principle of FBG Sensor

λn+∆λλ1,λ2, ..., λn, ..., λx

λn+∆λ

λnλ1,λ2, ..., λn, ..., λx

λ1,λ2, ......, λx

λn

When the fiber optic sensor is initially mounted to astructure, it's in resonance with laser wavelength ln.

Mounting block thatattaches fiber optic

sensor to the structure

Structure starts to pull mounting blocks apart ,which stretches the fiber optic sensor. Theresonance of fiber optic sensor is now shifted.

Reflection Without Strain

Reflection Without Strain

FBG SensingFBG Sensing

FBG Sensor Temperature Response

30 40 50 60 701550.7

1550.8

1550.9

1551

1551.1

1551.2

1551.3

Temperature,oC

Wav

elen

gth,

nm

Athermal, max shift: 21.6 pm (2.7 GHz) from 24oc to 70oC

Conventional, 10.4 pm/oC (1.3 GHz/oC)

Standard FBG Sensor Temperature Response

Athermal FBG Sensor Temperature Response

Utilization of FBG Characteristics for measurementUtilization of FBG Characteristics for measurement

Accelerometer

Accelerometer

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Other FBG SensorsOther FBG Sensors FBG For Structure Health MonitoringFBG For Structure Health Monitoring

FBG Railway SensingFBG Railway Sensing

Wav

elen

gth

(nm

)

Time (0.01 sec)

Typical Structure Health Monitoring Typical Structure Health Monitoring SystemSystemBroadband coupler λ1 λ2 λ3Broadband

Sourceλ1λ2 λ3……

Tunable Filter

Optical Subsystem

Reflected Light

λ2λ3… λ3… …

FBGsλ3 λ2λ1

Detection

Broadband coupler λ1 λ2 λ3Tunable

Source

λ1λ2 λ3……

Tunable Filter

Optical Subsystem

Reflected Light

λ2λ3… λ3… …

FBGsλ3 λ2λ1

Detection

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Broadband coupler

SLED or Laser

λ1 λ2 λ3Low Contrast Fabry-Perot

Filter

λ1λ2 λ3……

WavelengthLocker

Light Source Trigger Module

Timing Generator

Interrogation Unit (High Speed Signal Conditioning,

Sampling and ADC)

Microcontroller

Ethernet Interface

PC

Optical Subsystem

Electrical Subsystem

Pulsed Broadband

light

Reflected Light

FBG-LTDM Structure Monitoring System

λ2λ3… λ3… …

FBGs

ExternalInternal

λ3 λ2λ1 λ1λ2 λ3……

FBG-LTDM Structure Monitoring System Timing Example

Time (ns)

λ1

λ2

λ3

λ1 λ2 λ3

FBGs

λ1λ2 λ3…… λ2λ3… λ3… …

10 meters 10 meters 10 meters

Light Pulse

1st. Reflected Wavelength

2nd. Reflected Wavelength

3rd. Reflected Wavelength

50 100 150 200 250 150 200

Tp

Tfr

Tsw

TslLight Pulse

λ1λ2 λ3…… λ1λ2 λ3……Light Pulse

ConclusionsConclusions

•• Interconnect problem significant in ultra high Interconnect problem significant in ultra high speed data communicationspeed data communication

•• Performance of Electrical lnterconnects will limit Performance of Electrical lnterconnects will limit high performance system throughputhigh performance system throughput

•• OIs will provide significant performance boost OIs will provide significant performance boost but not completely replace but not completely replace EIsEIs

•• Optical Sensing will be deployed in new areas Optical Sensing will be deployed in new areas that were not feasible with electrical sensors that were not feasible with electrical sensors

WWavelength avelength DDivision ivision MMultiplexingultiplexingWDM enables transmission of multiple communication channels

through a single fiber using various colors of light

Detector

MUX =Multiplexer

DEMUX =Demultiplexer

EDFA =Erbium Doped Amplifier

λn

λ1

λn

λ1

λ2

λ1

λ2

λ1

Coarse WDM (CWDM): Transmission of a few widely spaced channels

Dense WDM (DWDM): Transmission of many closely spaced channels

MUX DEMUXEDFA Optical Fiber (Single fiber, multiple wavelengths)

Add/Drop Channel

Tunable Laser

Source or DFB Laser

Tunable Filter

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ReferencesReferences• International Technology Roadmap for Semiconductors (ITRS), 2001• R. Havemann and J.A Hutchby, “High-Performance Interconnects: An

integration Overview”, Proc. Of IEEE, Vol.89, May 2001 • D.A.B Miller, “Physical reasons for optical interconnections”, Int. Journal of

Optoelectronics 11, 1997, pp.155-168.• MEL-ARI: Optoelectronic interconnects for Integrated Circuits –

Achievements 1996-2000• Linking with light - IEEE Spectrum

http://www.spectrum.ieee.org/WEBONLY/publicfeature/aug02/opti.html• Optically Interconnected Computing Group

http://www.phy.hw.ac.uk/~phykjs/OIC/index.html• Optoelectronics-VLSI system integration Technological challenges

www.phy.hw.ac.uk/~phykjs/OIC/Projects/ SPOEC/MSEB2000/MSEB2000.pdf

optical interconnect and sensing detection and transmission · optical fiber an optical fiber is a...

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