Hypolito José KalinowskiHypolito José Kalinowski

National Institute of Photonics Science and Technology for Optical Communications –

UTFPR Branch

The 2009 Nobel Prize for Fibre The 2009 Nobel Prize for Fibre Optics and its OriginsOptics and its Origins

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One fibre to bring them all and in the brightness bind them

J.R.R. Tolkien, The Lord of the Rings

– adapted by the author

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FOTONICOMFOTONICOM

Brazilian Research Council (CNPq) funded institute for Photonics & Optical Communications

Head Institute: State University of Campinas (UNICAMP)

10 Research Groups~ 40 faculty~ 120 students & pos-doc

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OutlineOutline

• Electromagnetic Aspects

• Materials Aspects

• Putting all together

• B.K. (Before Kao)

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2009 Nobel Prize in Physics2009 Nobel Prize in PhysicsCharles Kuen KaoCharles Kuen Kao

The 2009 Nobel Prize in Physics honors three scientists, who have had important roles in shaping moder information technology, with one half to Charles Kuen Kao and with Willard Sterling Boyle and George Elwood Smith sharing the other half. Kao’s discoveries have paved the way for optical fiber technology, which today is used for almost all telephony and data communication. ...

K. C. Kao, G. A. Hockham (1966), "Dielectric-fibre surface waveguides for optical frequencies", Proc. IEE 113 (7): 1151–1158

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Once upon a time... (?)Once upon a time... (?)

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James Clerk MaxwellJames Clerk Maxwell

The Royal Society of Edinburgh, George Street, 07 Oct 2009

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Electromagnetism before 1864Electromagnetism before 1864

JBt

BE

B

E

0

0

0

Gauss Law

Non-existing magnetic monopoles

Faraday’s Law

Ampere’s Law

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Electromagnetism before 1864Electromagnetism before 1864

Taking the divergence

That’s OK. Repeating Correct for J constant,

but ... Electrodinamics, charge

conservation For all space!!! ???

constant

0

00

0

0

t

JBt

Bt

BE

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Maxwell EquationsMaxwell Equations

t

DJH

t

BE

B

D

0

Army’s Institute of Engineering Library (Rio de Janeiro)http://trailblazing.royalsociety.org/

J.C. Maxwell, “On physical lines of force”, Phil. Mag., 161ff, 1861

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Light as an Electromagnetic WaveLight as an Electromagnetic Wave

Transversal oscilations in the same E.M. Medium.

Velocity of propagation

Original agreement ~ 1,4%

00

1

cJ.C. Maxwell, “On physical lines of force”, Phil. Mag., 161ff, 1861Part III: The Theory of Molecular Vortices applied to Static Electricity

J.C. Maxwell, “A Dynamical Theory of the Electromagnetic Field ”, Phil. Trans. Royal Soc., 155, 459ff, 1865 (8 Dec 1864)

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Helmholtz EquationHelmholtz EquationPropagationPropagation

0),(][),(

),(),,,(

1

00222

)(

00

2

2

02

2

002

yxEyxE

eyxEtzyxE

c

t

P

t

EEE

tzi

Used by Maxwell, “A Dynamical...”, op. cit.

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Eletromagnetism after MaxwellEletromagnetism after Maxwell

Free Space Eletromagnetism

Linear, isotropic, dispersionless medium, free of charges or currents

Elementary solutions based on propagating harmonic waves (superposition).

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Free Space Electromagnetic Free Space Electromagnetic PropagationPropagation

Electromagnetic wavesWireless telegraphyRadioTelevisionCommunication satellitesMicrowave linksWireless & mobile communications

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Eletromagnetism after MaxwellEletromagnetism after Maxwell

Eletromagnetism in material mediaPolarization (P) and Magnetization (M)

Non linear, anisotropic, dispersive media Solutions based in harmonic propagating waves

(superposition wave packets)

HHMHB

EEPED

m

e

00

00

)1()(

)1(

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Dielectric WaveguidesDielectric Waveguides

Limits and discretization of solutions– Fundamentally derived from boundary conditions for

the electromagnetic fields– Guided modes– Leaky modes

Characteristic equation for modal solutions– Determines modal field patterns & associated

parameters– Dispersion relation

Interest for optics: frequency region where only one mode can propagate – singlemode waveguide

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Near infrared

Frequency

Wavelength1.6

229

1.0 0.8 µm0.6 0.41.8 1.4

UV

(vacuum) 1.2

THz193 461

0.2

353

Longhaul Telecom

Regional Telecom

Local Area Networks850 nm

1550 nm

1310 nmCD 780 nm

HeNe Lasers633 nm

Optical SpectrumOptical Spectrum

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Optical WaveguideOptical Waveguide

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Fibre Optics (after Kao)Fibre Optics (after Kao)

Made from Silica (SiO2).

Silica is the most abundant material on Earth’s surface.

Reduction of impurities and fabrication imperfections.

Silica obtained from Quartz powder, because it has less impurities than common sand.

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Once upon a time... ( again !?)Once upon a time... ( again !?)

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Glass and its BenefitsGlass and its Benefits(Accidental ?) Discovery about 2500 BCEgypt (pots), Syria (blown glass), Assiria (first

‘manual’ ~650BC)Spread with Fenitian, Roman, VenetianVenice became the principal source of glass in

13th century– Pots, bottles, tubes, flat glass, mirrors, ...

Glass changed society at the end of the Medioevo, Renaissance and beggining of Modern age

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A World of GlassA World of GlassA. Macfarlane & G. Martin, Science A. Macfarlane & G. Martin, Science 305 (5689)305 (5689), 1407, 2004, 1407, 2004

Glass in Science– Widespread applications

in all Science areas– Instruments– Fundamenal experiments

Glass in dayly use– Windows (light,

cleaning)– Commerce (exhibit,

storage, transport)– Greenhouses

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There are many other useful applications of glass that altered everyday life from the 15th century onward. Among them were storm-proof lanterns, enclosed coaches, watch-glasses, lighthouses, and street lighting. The sextant required glass, and the precision chronometer invented by Harrison in 1714, which provided a solution to calculating longitude at sea, would not have been possible without glass. Thus, glass directly contributed to navigation and travel. Then, there was the contribution of glass bottles, which increasingly revolutionized the distribution and storage of drinks, foods, and medicines. Indeed, glass bottles created a revolution in drinking habits by allowing wine and beer to be more easily stored and transported. First through drinking vessels and windows, then through lanterns, lighthouses, and greenhouses, and finally through cameras, television, and many other glass artifacts, our modern world has emerged from a sea of glass.

The different applications of glass are all interconnected--windows improved working conditions, spectacles lengthened working life, stained glass added to the fascination and mystery of light and, hence, a desire to study optics. The rich set of interconnections of this largely invisible substance have made glass both fascinating and powerful, a molten liquid that has shaped our world.

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Glass FibresGlass FibresMade by Egiptians ~1600 A.C

– Fibre decorated potery dated ~1375 ACExternal fiber decorated glass cups, VeniceReamur (1700´s): glass fibres

– Fibres as this as spider´s web threads would be flexible and could be tecelagem

XIX Century: glass fibres and cloths for decorative purposes

C.V. Boys (1887): ‘elastic’ fibre ~2,5μm– Glass quartz (silica) [as resistants as steel wires]– Scientific apparatus at end of 19th century and begining of

20th (torsion balance, balistic galvanometers, e.g.)

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Light GuidingLight Guiding

Total internal refractionLight beams guided in

water jetsPopular shows during

second half of 19th century– J. Tyndall

D. Collandon “On the reflectivity of a ray of light inside a parabolic liquid stream” Comptes Rendus 15, 800-802, 1842.

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Dissemination ?Dissemination ?

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Fibre ImagingFibre Imaging

Light transmission in fibres– Illumination (Odontology,

Medicine) Lucite rods

– Imaging (Endoscopy) Fibre bundles

Image transmission– Television

Fibre bundles

High losses on surfaces and bends

H. Lamm, Zeitsch. Instrumentenkunden, 579, 1930

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Fibre Optics – 1950’s-1960’sFibre Optics – 1950’s-1960’s

Losses in bundles due to fibre contactNeeded to avoid surface lossesMetallic deposition on surface

– Still high losses99% reflector, 100 reflections 36,6% lost > 1000 reflections per meter of fibre

Cladding with lower refractive index material– Total internal reflection inside fibre– Dielectric materials

Honey, margarine, cooking (olive ?) oil Plastic fibres cladded with bee’s wax Plastic cladded glass fibres A.C.S. Van Heel, Die Ingenieur 24(12), 1953

Nature 173, 39, 1954

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Fibre ImagingFibre Imaging

H. Hopkins & N.S. Kapany– Gastric endoscope– Fibre bundles (1000+), l =75 cm

B. Hirschowitz & L. Curtiss– Drawing of high refractive index glass fibres– Glass cladded fibres (Curtiss)

8 km/hr, “low” atenuation, external jacket40.000 fibre bundles

H. Hopkins & N.S. Kapany, Nature 173, 39-41, 1954

L.E.Curtiss, Glass fibers optical devices, US Patent 3589793, dep. 1957, conc. 1971.B. Hirschowitz, Gastroenterology 35, 50-53, 1958

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Curtiss’ ProcessCurtiss’ Process Curtiss introduced the

preforma concept– Concentric rods of high/low

refractive index Basically it is the process

currently used– Several methods to obtain the

preforma– Fundamental for

microstructured fibres Endoscopes disseminated

during ’60 of century XX– Gastroenterology– Industrial use (inspection)

High n Low n

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Fibre Optics before KaoFibre Optics before Kao

Luminous Fountains Glass fibres for industrial use (thermal insulation, e.g.) Glass or plastic illuminators Optical card readers Cryptography (bundle scrambling) Gastroenteroscopes Endoscopes & surgery illuminators Image intensifiers faceplates

Basically limited to short lenghts (~ m) due to high glass losses and bend losses during normal use

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Lasers (1958-1966)Lasers (1958-1966)

Optical frequencies carrier– Increase in channel number (FDM)

High fluence– Long distance links, free space direct links

Heterostructure semiconductor laser– CW operation at room temperature– Low electrical power– Small devices

Proposition (& testing) of confined beams (mirros, lenses) in burried pipes, direct links– High sensitivity to temperature and environmental conditions

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Fibre Optics for CommunicationsFibre Optics for Communications

Study of factors contributing to loss– Atenuation due to

impurities, chemical structure, light scattering and geometrical imperfections in the glass

Possible use in optical links < 20 dB/km– ~ 1GHz

K. C. Kao, G. A. Hockham (1966), "Dielectric-fibre surface waveguides for optical frequencies", Proc. IEE 113 (7): 1151–1158

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Kao & Hockham Kao & Hockham

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• Literature review• Analysis of properties, several materials

• Methodology• Theory• Experiments• Model comparison

• Results & Discussion• Proposition & Conclusions

LP01

LP11

LP21

LP12

TE02, TM02

HE12 + EH11

EH + HE

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Conclusions – Kao & HockhamConclusions – Kao & Hockham

– Practical optical guide, o

– Flexíble, mec. tol. ~10%– ncore - nclad ~1%– Singlemode HE11

– Information capacity > 1 GHz

– Probable advantage in cost (coaxial, radio)

– Dielectric with low loss– Required loss < 20dB/km

(fundamental involved limits much lower)

Fibras da época ~1000 dB/km (melhoria de 1098 !!)

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Fibres just afterFibres just after

Small laboratory demos– Video transmission with bundle of 70, 20m long,

fibras (1 dB/m) (1967)

Search for low loss glasses– Several visits to Bell, American Optics, Corning,

Bausch & Lomb, ... (Kao)

Graded index fibres (Japan)

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Ultra pure Glass Fibre OpticsUltra pure Glass Fibre Optics

Loss measurements in optical glasses ( l ~ 30 cm)– Differential spectrometry ( l = 20 cm)

Fused silica losses – (< 1ppm impurities)– < 5 dB/km

M.W. Jones & K.C. Kao (1969), “Spectrophotometric studies of ultra low loss optical glasses 2:double beam method", J. Sci. Instrum.: 331-335

K.C. Kao & T.W. Davies (1968), “Spectrophotometric studies of ultra low loss optical glasses 1:single beam method", J. Sci. Instrum.: 331-335

Possible to purify optical glasses to obtain required loss !

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6 years conquist6 years conquist

Glass purifying Double crucilble process (already used in past)

– Dyot (sugar molasses optimization) Flame photolysis (Corning)

– Fibre SiO2/SiO2:Ti– Scattering loss ~ 7 dB/km– “Lowest value of total loss among all used waveguide was

approximately 20 dB/km”– British Post Office measurements confirmed 15 dB/km (@633nm)

Fibres SiO2/SiO2:Ge (Corning)– 4 dB/km loss (Junho, 1972)– Spectral measurements forecast < 2dB/km ~800+ nm

D.B. Keck, R.D. Maurer & P.C. Schultz, “On the ultimate limit of attenuation in glass optical waveguides”, Appl. Phys. Letters 22(7), 307-309, 1973

F.P. Kapron, D.B. Keck & R.D. Maurer, “Radiation losses in glass optical waveguides”, Appl. Phys. Letters 17, 423-425, 1970

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Contemporaneous HistoryContemporaneous History

IEE Centenary– Colour digital TV transmission through fibre optics

Initial optical communication systems– Graded index fibres ~840nm (AT&T)

Return to singlemode fibres– Zero dispersion @ 1300nm– Lower losses– Minimum loss @ 1550 nm– Dry fibres– 30-50 km span link between repeaters– Submarine systems (TAT 1 – 1988)

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EvolutionEvolution

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Submarine optical cablesSubmarine optical cables

420,000 km of fiber deployed on 100 undersea optical fiber systems

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What we would lostWhat we would lost

Frequent high quality long distance callsMobile telephonyHigh quality TV & distributed services Internet, WebYouTube !

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Bandwidth ?Bandwidth ?

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Power Consumption ?Power Consumption ?

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The Future ?The Future ?“If optical fibers and semiconductor

lasers were proposed today, we would use (POTS) services on cooper pairs

forever.” Tyinge Ly, 2002

“I cannot think of anything that can replace fiber optics.

In the next 1000 years, I cannot think of a better system.

But don’t believe what I say, because I didn’t believe what experts said

either.” Charles K. Kao, interview to the Radio

Television Hong Kong, 2009

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Grazie per la vostra attenzione !

C.K. Kao Nobel Lecture