The Origins of Fiber Optic Communications

8/14/2019 The Origins of Fiber Optic Communications

1/34

The Origins of FiberThe Origins of Fiber

Optic CommunicationsOptic CommunicationsCh 1Ch 1

Fiber Optics TechniciansFiber Optics TechniciansManual, 3Manual, 3rdrd. Ed. Ed

Jim HayesJim Hayes


2/34

Early Optical CommunicationsEarly Optical Communications

The French used semaphores toThe French used semaphores to

transmit messages in the 1790stransmit messages in the 1790s

Later systems also sent opticalLater systems also sent opticalsignals through the airsignals through the air

But clouds, rain, and other atmosphericBut clouds, rain, and other atmospheric

disturbances can disrupt optical signalsdisturbances can disrupt optical signals

sent through the airsent through the air Electric signals through wires avoid thatElectric signals through wires avoid that

problemproblem Image from Wikipedia SemaphoresImage from Wikipedia Semaphores


3/34

Guiding Light With WaterGuiding Light With Water

Light in a stream ofLight in a stream of

water stays insidewater stays inside

the water and bendsthe water and bends

with itwith it

This was firstThis was first

demonstrated in thedemonstrated in the

1840s1840s Image fromImage from

glenbrook.k12.il.us/gbssciglenbrook.k12.il.us/gbssci


4/34

Refraction (Bending) of LightRefraction (Bending) of Light

Ray A comes fromRay A comes from

straight up andstraight up and

does not benddoes not bend

muchmuch Ray B comes at aRay B comes at a

shallow angle andshallow angle and

bends a lot morebends a lot more Image from seafriends.org.nzImage from seafriends.org.nz


5/34

The View From UnderwaterThe View From Underwater

Underwater, the light always shines downUnderwater, the light always shines downsteeply, even when the Sun is low in thesteeply, even when the Sun is low in the

skysky

The whole sky appears in a limited roundThe whole sky appears in a limited round

area called Snells Windowarea called Snells Window Image from seafriends.org.nzImage from seafriends.org.nz


6/34

Light Coming Out of WaterLight Coming Out of Water

Animation on link Ch 1bAnimation on link Ch 1b http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=66http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=66


7/34

Total Internal ReflectionTotal Internal Reflection

There is a critical angle atThere is a critical angle atwhich no light can bewhich no light can berefracted at all, so 100% ofrefracted at all, so 100% of

the light is reflectedthe light is reflected Light is trapped in the waterLight is trapped in the water

and cannot escape into theand cannot escape into theairair

This works with any denseThis works with any densemedium, such as plastic ormedium, such as plastic orglass, the same way it worksglass, the same way it workswith waterwith water Image fromImage from glenbrook.k12.il.usglenbrook.k12.il.us


8/34

How Light Travels in FiberHow Light Travels in Fiber

Image from ece.umd.edu/~davisImage from ece.umd.edu/~davis


9/34

Bare FiberBare Fiber

During 1920-1950,During 1920-1950,

thin, flexible rods ofthin, flexible rods of

glass or plasticglass or plastic

were used to guidewere used to guidelightlight

Such bare fibersSuch bare fibers

require air outsiderequire air outsideeach fibereach fiber Image from WikipediaImage from Wikipedia


10/34

Fiber With CladdingFiber With Cladding

Developed in 1954Developed in 1954by van Heel, Hopkinsby van Heel, Hopkins& Kapany& Kapany

Cladding is a glass orCladding is a glass or

plastic cover aroundplastic cover aroundthe corethe core

Protects the total-Protects the total-reflection surfacereflection surface

contaminationcontamination Reduces cross-talkReduces cross-talk

from fibers infrom fibers inbundlesbundles


11/34

Medical ImagingMedical Imaging

By 1960, glass-clad fibers wereBy 1960, glass-clad fibers were

available for medical instruments, toavailable for medical instruments, to

look inside the bodylook inside the body

The glass was unable to transmitThe glass was unable to transmit

light far enough for communications,light far enough for communications,

because of impuritiesbecause of impurities

Attenuation (loss of light) was 1 decibelAttenuation (loss of light) was 1 decibel

per meterper meter


12/34

DecibelsDecibels

Decibels are a logarithmic scale of powerDecibels are a logarithmic scale of power

Abbreviated dBAbbreviated dB

A loss of 10 decibels means only 10% ofA loss of 10 decibels means only 10% of

the light gets throughthe light gets through A loss of 20 dB means 1% of the light getsA loss of 20 dB means 1% of the light gets

throughthrough

Sunglasses stop 99% of light, so they cause aSunglasses stop 99% of light, so they cause aloss of 20 dBloss of 20 dB

For communications, loss must be noFor communications, loss must be no

more than 10 or 20 decibels per kilometermore than 10 or 20 decibels per kilometer


13/34

Optical Fiber in 1966Optical Fiber in 1966

Charles Kao developed a fiber thatCharles Kao developed a fiber that

could transmit 1 GHz (One billion bitscould transmit 1 GHz (One billion bits

per second)per second)

But attenuation was 1000 dB/km, soBut attenuation was 1000 dB/km, so

it could not transmit light far enoughit could not transmit light far enough

for practical communicationsfor practical communications


14/34

CorningCorning

Corning scientists developed low-Corning scientists developed low-

attenuation silica glass fibers in 1970attenuation silica glass fibers in 1970

Corning Video: At The Speed of LightCorning Video: At The Speed of Light

Link Ch 1c on my Web pageLink Ch 1c on my Web page

(samsclass.info)(samsclass.info)


15/34

Singlemode and Multimode FiberSinglemode and Multimode Fiber

Singlemode fiber has a core diameterSinglemode fiber has a core diameter

of 8 to 9 micronsof 8 to 9 microns

Multimode fiber has a core diameterMultimode fiber has a core diameter

of 50 or 62.5 micronsof 50 or 62.5 microns

Both have a cladding diameter ofBoth have a cladding diameter of

125 microns125 microns


16/34

Optical Fiber in 1977Optical Fiber in 1977

Telephone signals used infrared lightTelephone signals used infrared lightwith a wavelength of 850 nm to sendwith a wavelength of 850 nm to senddata at 6.2 Mbps and 45 Mbpsdata at 6.2 Mbps and 45 Mbps

Loss was 2 dB per kmLoss was 2 dB per km Repeaters were required every fewRepeaters were required every few

kilometerskilometers

The repeaters were electro-optical The repeaters were electro-optical converting the light to electricity andconverting the light to electricity andthen back to lightthen back to light


17/34

TAT-8TAT-8

In 1988 AT&T laid theIn 1988 AT&T laid thefirst fiber-opticfirst fiber-optictransatlantic telephonytransatlantic telephonycablecable

3,148 miles long3,148 miles long Connected NorthConnected North

America to FranceAmerica to France Repeaters every 40Repeaters every 40

milesmiles 565 Mbps bandwidth565 Mbps bandwidth Used 1300 nm lightUsed 1300 nm light Attenuation 0.4 dB/kmAttenuation 0.4 dB/km

Image from att.comImage from att.com

Info from link Ch 1eInfo from link Ch 1e www.greatachievements.orgwww.greatachievements.org/?id=3706/?id=3706
http://www.greatachievements.org/?id=3706http://www.greatachievements.org/?id=3706http://www.greatachievements.org/?id=3706http://www.greatachievements.org/?id=3706http://www.greatachievements.org/?id=3706http://www.greatachievements.org/?id=3706


18/34

Fiber AmplifierFiber Amplifier

Special fiber with Erbium atoms in it isSpecial fiber with Erbium atoms in it is

used to amplify light without changing it toused to amplify light without changing it to

an electrical signal firstan electrical signal first

Uses stimulated emission, the sameUses stimulated emission, the sameprinciple that makes lasers workprinciple that makes lasers work Image from rp-photonics.com (Link Ch 1g)Image from rp-photonics.com (Link Ch 1g)


19/34

Wavelength Division MultiplexingWavelength Division Multiplexing

(WDM)(WDM)

Several signals can be sent throughSeveral signals can be sent through

the same fiber simultaneously bythe same fiber simultaneously by

using different wavelengths (colors)using different wavelengths (colors)

of lightof light That means more bandwidthmoreThat means more bandwidthmore

data per seconddata per second


20/34

Freeway AnalogyFreeway Analogy

TAT-8 in 1980TAT-8 in 1980 565 Mbps565 Mbps

Electro-opticalElectro-opticalrepeatersrepeaters

TAT-12/13 in 1996TAT-12/13 in 1996 2.5 Gbps2.5 Gbps

Optical amplifiersOptical amplifiers

19981998

20 Gbps20 Gbps WDM with 8WDM with 8

wavelengthswavelengths Image from www2.rad.comImage from www2.rad.com

(Link Ch 1j)(Link Ch 1j)


21/34

Dense Wavelength DivisionDense Wavelength Division

Multiplexing (DWDM)Multiplexing (DWDM)

Uses up to 100 wavelengths throughUses up to 100 wavelengths through

a single fibera single fiber

Bandwidth up to 1 Tbps (1000 Gbps)Bandwidth up to 1 Tbps (1000 Gbps)


22/34

Lennie Lightwave'sLennie Lightwave's

Guide To Fiber OpticsGuide To Fiber Optics

BasicsBasicsFrom jimhayes.com/lennielwFrom jimhayes.com/lennielw


23/34

Fiber Optics HistoryFiber Optics History

Fiber optics began about 30 yearsFiber optics began about 30 years

ago in the R&D labs (Corning, Bellago in the R&D labs (Corning, Bell

Labs, ITT UK, etc.)Labs, ITT UK, etc.)

First installed in Chicago in 1976First installed in Chicago in 1976

By the early 1980s, fiber networksBy the early 1980s, fiber networks

connected the major cities on eachconnected the major cities on each

coast.coast.


24/34

The 1980sThe 1980s

By the mid-80s, fiber was replacingBy the mid-80s, fiber was replacingall the telco copper, microwave andall the telco copper, microwave andsatellite linkssatellite links

In the 90s, CATV started using fiberIn the 90s, CATV started using fiberto enhance the reliability of theirto enhance the reliability of theirnetworksnetworks

CATV companies also discovered theyCATV companies also discovered theycould offer phone and Internet servicecould offer phone and Internet serviceon that same fiber and greatly enlargedon that same fiber and greatly enlargedtheir marketstheir markets


25/34

Computers and LANsComputers and LANs

Started using fiber about the sameStarted using fiber about the sametime as the telcostime as the telcos

Industrial links were among the firstIndustrial links were among the first

as the noise immunity of fiber and itsas the noise immunity of fiber and itsdistance capability make it ideal fordistance capability make it ideal forthe factory floorthe factory floor

Mainframe storage networks cameMainframe storage networks camenext, the predecessors of today'snext, the predecessors of today'sfiber SANs (storage area networks.)fiber SANs (storage area networks.)


26/34

Other ApplicationsOther Applications

Aircraft, ship and automobile dataAircraft, ship and automobile data

busesbuses

CCTV for securityCCTV for security

Links for consumer digital stereoLinks for consumer digital stereo

Today fiber optics is either theToday fiber optics is either the

dominant medium or a logical choicedominant medium or a logical choicefor every communication systemfor every communication system


27/34

Which Fiber Optics?Which Fiber Optics?

"Outside Plant" fiber optics are used"Outside Plant" fiber optics are used

in telephone networks or CATVin telephone networks or CATV

"Premises" fiber optics are usedin"Premises" fiber optics are usedin

buildings and campusesbuildings and campuses

Just like "wire" which can mean lotsJust like "wire" which can mean lots

of different things - power, security,of different things - power, security,

HVAC, CCTV, LAN or telephone -HVAC, CCTV, LAN or telephone -

fiber optics is not all the same.fiber optics is not all the same.


28/34

Installing Fiber OpticsInstalling Fiber Optics

Fiber is harder to install than 100 MbpsFiber is harder to install than 100 Mbpscopper Ethernet cablecopper Ethernet cable

But fiber is MUCH faster, so theBut fiber is MUCH faster, so theinfrastructure wont need to be upgradedinfrastructure wont need to be upgradedso soonso soon And gigabit Ethernet is harder to installAnd gigabit Ethernet is harder to install

LAN copper cable is delicate. It only has aLAN copper cable is delicate. It only has a

25 pound pulling tension limit and kinks25 pound pulling tension limit and kinkswill ruin the high speed performancewill ruin the high speed performance Fiber has more strength and greater toleranceFiber has more strength and greater tolerance

to abuse than copper wireto abuse than copper wire


29/34

Safety First!Safety First!

The light in the fiber can burn yourThe light in the fiber can burn your

retinaretina

NEVER look into a fiber unless youNEVER look into a fiber unless you

know no light is present - use aknow no light is present - use a

power meter to check itpower meter to check it

The infrared light is invisibleThe infrared light is invisible


30/34

Fiber ShardsFiber Shards

When you cleave fiber, there areWhen you cleave fiber, there are

small scraps of glass produced.small scraps of glass produced.

These scraps are very dangerous!These scraps are very dangerous!

The cleaved ends are extremelyThe cleaved ends are extremely

sharp and can easily penetrate yoursharp and can easily penetrate your

skinskin

They are even worse in your eyes,They are even worse in your eyes,

mouth, etc.mouth, etc.


31/34

Safety RulesSafety Rules

Wear glasses or safety glassesWear glasses or safety glasses Dispose of all scraps properly:Dispose of all scraps properly:

Put scraps on black tapePut scraps on black tape

Use a properly marked trashcanUse a properly marked trashcan Work on a black pad which makesWork on a black pad which makes

the slivers of glass easier to spotthe slivers of glass easier to spot

Do not drop scraps on the floorDo not drop scraps on the floor Do not eat or drink anywhere nearDo not eat or drink anywhere near

the work areathe work area


32/34

Chemical SafetyChemical Safety

Fiber optic splicing and terminationFiber optic splicing and termination

use various chemical adhesives anduse various chemical adhesives and

cleanerscleaners

Follow the instructions for useFollow the instructions for use

carefullycarefully

Isopropyl alcohol, used as a cleaner,Isopropyl alcohol, used as a cleaner,

is flammableis flammable


33/34

Zero Tolerance for DirtZero Tolerance for Dirt

Airborne particles are about the sizeAirborne particles are about the size

of the core of Single Mode fiberof the core of Single Mode fiber

They absorb lots of light and mayThey absorb lots of light and may

scratch connectors if not removedscratch connectors if not removed

Dirt on connectors is the biggest causeDirt on connectors is the biggest cause

of scratches on polished connectors andof scratches on polished connectors and

high loss measurementshigh loss measurements


34/34

Hygiene RulesHygiene Rules

Work in a clean area avoid dustWork in a clean area avoid dust

Keep dust caps on all connectorsKeep dust caps on all connectors

Use lint free pads and isopropylUse lint free pads and isopropylalcohol to clean connectorsalcohol to clean connectors

The Origins of Fiber Optic Communications

Documents

Transcript of The Origins of Fiber Optic Communications