The 2009 Nobel Prize for Fibre Optics and its Origins

1. Hypolito José Kalinowski National Institute of Photonics Science and Technology for Optical Communications – UTFPR Branch The 2009 Nobel Prize for Fibre Optics and its Origins

2. 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

3. 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 FOTONICOM

4. Electromagnetic Aspects Materials Aspects Putting all together B.K. (Before Kao) Outline

5. 2009 Nobel Prize in PhysicsCharles 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. IEE113 (7): 1151–1158

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

7. James Clerk Maxwell The Royal Society of Edinburgh, George Street, 07 Oct 2009

8. Electromagnetism before 1864 • Gauss Law • Non-existing magnetic monopoles • Faraday’s Law • Ampere’s Law

9. Electromagnetism before 1864 • Taking the divergence • That’s OK. • Repeating • Correct for J constant, but ... • Electrodinamics, charge conservation • For all space!!! ???

10. Maxwell Equations 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

11. Light as an Electromagnetic Wave • Transversal oscilations in the same E.M. Medium. • Velocity of propagation • Original agreement ~ 1,4% J.C. Maxwell, “On physical lines of force”, Phil. Mag., 161ff, 1861 Part 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)

12. Helmholtz EquationPropagation Used by Maxwell, “A Dynamical...”, op. cit.

13. Free Space Eletromagnetism Linear, isotropic, dispersionless medium, free of charges or currents Elementary solutions based on propagating harmonic waves (superposition). Eletromagnetism after Maxwell

14. Electromagnetic waves Wireless telegraphy Radio Television Communication satellites Microwave links Wireless & mobile communications Free Space Electromagnetic Propagation

15. Eletromagnetism after Maxwell • Eletromagnetism in material media • Polarization (P) and Magnetization (M) • Non linear, anisotropic, dispersive media • Solutions based in harmonic propagating waves (superposition  wave packets)

16. 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 Dielectric Waveguides

17. Optical Spectrum 193 229 353 461 THz Frequency Near infrared UV Wavelength (vacuum) 1.0 0.6 1.8 1.6 1.4 1.2 0.8 0.4 0.2 µm HeNe Lasers 633 nm Longhaul Telecom Regional Telecom Local Area Networks 1550 nm CD 780 nm 1310 nm 850 nm

18. Optical Waveguide

19. 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. Fibre Optics (after Kao)

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

21. (Accidental ?) Discovery about 2500 BC Egypt (pots), Syria (blown glass), Assiria (first ‘manual’ ~650BC) Spread with Fenitian, Roman, Venetian Venice 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 Glass and its Benefits

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

23. 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.

24. Made by Egiptians ~1600 A.C Fibre decorated potery dated ~1375 AC External fiber decorated glass cups, Venice Reamur (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.) Glass Fibres

25. Light Guiding • Total internal refraction • Light beams guided in water jets • Popular 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.

26. Dissemination ?

27. Fibre 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

28. Losses in bundles due to fibre contact Needed to avoid surface losses Metallic deposition on surface Still high losses 99% 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 Fibre Optics – 1950’s-1960’s A.C.S. Van Heel, Die Ingenieur 24(12), 1953 Nature 173, 39, 1954

30. 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 jacket 40.000 fibre bundles Fibre Imaging 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

31. Curtiss’ 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) Low n High n

32. 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 Fibre Optics before Kao Basically limited to short lenghts (~ m) due to high glass losses and bend losses during normal use

33. 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 Lasers (1958-1966)

34. Fibre 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 • a < 20 dB/km • ~ 1GHz K. C. Kao, G. A. Hockham (1966), "Dielectric-fibre surface waveguides for optical frequencies", Proc. IEE113 (7): 1151–1158

35. Kao & Hockham

36. LP01 LP21 LP11 TE02, TM02 • Literature review • Analysis of properties, several materials • Methodology • Theory • Experiments • Model comparison • Results & Discussion • Proposition & Conclusions LP12 HE12 + EH11 EH + HE

37. Conclusions – Kao & Hockham • Practical optical guide, F ~100 lo • 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 !!)

38. 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) Fibres just after

39. Loss measurements in optical glasses ( l ~ 30 cm) Differential spectrometry ( Dl = 20 cm) Fused silica losses (< 1ppm impurities) < 5 dB/km Ultra pure Glass Fibre Optics K.C. Kao & T.W. Davies (1968), “Spectrophotometric studies of ultra low loss optical glasses 1:single beam method", J. Sci. Instrum.: 331-335 M.W. Jones & K.C. Kao (1969), “Spectrophotometric studies of ultra low loss optical glasses 2:double beam method", J. Sci. Instrum.: 331-335  Possible to purify optical glasses to obtain required loss !

40. 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 6 years conquist F.P. Kapron, D.B. Keck & R.D. Maurer, “Radiation losses in glass optical waveguides”, Appl. Phys. Letters 17, 423-425, 1970 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

41. 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) Contemporaneous History

42. Evolution

43. Submarine optical cables 420,000 km of fiber deployed on 100 undersea optical fiber systems

44. Frequent high quality long distance calls Mobile telephony High quality TV & distributed services Internet, Web YouTube ! What we would lost

45. Bandwidth ?

46. Power Consumption ?

47. 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

48. C.K. Kao Nobel Lecture Grazie per la vostra attenzione !