66%美國人指不值獲獎
奧巴馬表示，有些情況使用戰爭是「必要」、「公義的」，例如自衞、援助被入侵的國家、人道理由，包括有政府屠殺人民或某地方爆發不可收拾的內戰。但他說︰「無論理由多充分，戰爭始終是人類悲劇。」他還提及戰爭以外的手段，強調外交和制裁的重要性，例如對付有核問題的伊朗 和北韓 ，或對付殘害人民的蘇丹 、剛果、緬甸。
Sand from centuries past;
Send future voices fast.
A Nobel Lecture
organized by the Royal Swedish Academy of Sciences
and
The Prize Committee in Physics
delivered by
Mrs Gwen MW Kao
on behalf of
Prof Charles K Kao
Nobel Laureate in Physics 2009
8 December 2009
Aula Magna
Stockholm University
1. Introduction
It is sad that my husband, Professor Charles Kao, is unable to give this lecture to you
himself. As the person closest to him, I stand before you to honour him and to speak for him. He is very very proud of his achievements for which the Nobel Foundation honours him. As are we all!
In the 43 years since his seminal paper of 1966 that gave birth to the ubiquitous glass fiber cables of today, the world of telephony has changed vastly. It is due to Professor Kao’s persistence in the face of skepticism that this revolution has occurred.
In the 1970s the pre-production stage moved to ITT Corp Roanoke VA, USA. Whilst Charles worked there, he received two letters. One contained a threatening message accusing him of
releasing an evil genie from its bottle; the other, from a farmer in China, asked for a means to allow him to pass a message to his distant wife to bring his lunch. Both letter writers saw a future that has since become past history.
In the 1960s, our children were small. Charles often came home later than normal – dinner
was waiting as were the children. I got very annoyed when this happened day after day. His words,maybe not exactly remembered, were –
‘Please don’t be so mad. It is very exciting what we are doing; it will shake the world one day!’
I was sarcastic, ‘Really, so you will get the Nobel Prize, won’t you!
He was right – it has revolutionized telecommunications.
2. The early days
In 1960, Charles joined Standard Telecommunications Laboratories Ltd. (STL), a subsidiary of ITT Corp in the UK, after having worked as a graduate engineer at Standard Telephones and Cables in Woolwich for some time. Much of the work at STL was devoted to improving the capabilities of the existing communication infrastructure with a focus on the use of millimeter wave transmission systems.
Millimeter waves at 35 to 70 GHz could have a much higher transmission capacity. But the
waters were uncharted and the challenges enormous, since radio waves at such frequencies could not be beamed over long distances due to beam divergence and atmospheric absorption. The waves
had to be guided by a waveguide. And in the 1950’s, R&D work on low loss circular
waveguides –HE-11 mode – was started. A trial system was deployed in the 1960s. Huge sums were invested, and more were planned, to move this system into the pre-production stage. Public expectation for new telecommunication services such as the video phone had heightened.
Charles joined the long-haul waveguide group led by Dr Karbowiak at STL. He was excited
to see an actual circular waveguide. He was assigned to look for new transmission methods for microwave and optical transmission. He used both ray optics and wave theory to gain a better understanding of waveguide problems – then a novel idea. Later, his boss encouraged him to pursue a doctorate while working at STL. So Charles registered at University College London and completed the dissertation ‘Quasi-Optical Waveguides’ in two years.
The invention of the laser in 1959 gave the telecom community a great dose of optimism
that optical communication could be just around the corner. The coherent light was to be the new information carrier with capacity a hundred thousand times higher than point-to-point microwaves –based on the simple comparison of frequencies: 300 terahertz for light versus 3 gigahertz for microwaves.
The race between circular microwave waveguides and optical communication was on, with
the odds heavily in favour of the former. In 1960, optical lasers were in their infancy, demonstrated at only a few research laboratories, and performing much below the needed specs. Optical systems seemed a non-starter.
But Charles still thought the laser had potential. He said to himself: ‘How can we
dismiss the laser so readily? Optical communication is too good to be left on the theoretical shelf.’
He asked himself the obvious questions:
1. Is the ruby laser a suitable source for optical communication?
2. What material has sufficiently high transparency at such wavelengths?
At that time only two groups in the world were starting to look at the transmission aspect of
optical communication, while several other groups were working on solid state and semiconductor lasers. Lasers emit coherent radiation at optical frequencies, but using such radiation for communication appeared to be very difficult, if not impossible. For optical communication to fulfill its promises, many serious problems remained to be solved.
3. The key discovery
In 1963 Charles was already involved in free space propagation experiments: the rapid
progress of semiconductor and laser technology had opened up a broader scope to explore optical communication realistically. With a helium-neon laser beam directed to a spot some distance away, the STL team quickly discovered that distant laser light flickered. The beam danced around several beam diameters because of atmospheric fluctuations.
The team also tried to repeat experiments done by other research laboratories around the
world. For example, they set up con-focal lens experiments similar to those at Bell Labs: a series of convex lenses were lined up at intervals equal to the focal length. But even at the dead of night when the air was still and even with refocusing every 100 meters, the beam refused to stay within the lens aperture.
Bell Labs experiments using gas lenses were abandoned due to the difficulty of providing
satisfactory insulation while maintaining the profiles of the gas lenses. These experiments were struggles in desperation, to control light travelling over long distances.
At STL the thinking shifted towards dielectric waveguides. Dielectric means a non-conductor of electricity; a dielectric waveguide is a waveguide consisting of a dielectric
cylinder surrounded by air. Dr Karbowiak suggested Charles and three others to work on his idea of a thin film waveguide.
But thin film waveguides failed: the confinement was not strong enough and light would escape as it negotiates a bend.
When Dr Karbowiak decided to emigrate to Australia, Charles took over as the project
leader and he then recommended that the team should investigate the loss mechanism of dielectric materials for optical fibers.
A small group worked on methods for measuring material loss of low-loss transparent
materials. George Hockham joined him to work on the characteristics of dielectric waveguides.
With his interest in waveguide theory, he focused on the tolerance requirements for an optical fiber waveguide; in particular, the dimensional tolerance and joint losses. They proceeded to systematically study the physical and waveguide requirements on glass fibers.
In addition, Charles was also pushing his colleagues in the laser group to work towards a
semiconductor laser in the near infrared, with emission characteristics matching the diameter of a single-mode fiber. Single mode fiber is optical fiber that is designed for the transmission of a single ray or mode of light as a carrier. The laser had to be made durable, and to work at room temperatures without liquid nitrogen cooling. So there were many obstacles. But in the early 1960s,
esoteric research was tolerated so long as it was not too costly.
Over the next two years, the team worked towards the goals. They were all novices in the
physics and chemistry of materials and in tackling new electromagnetic wave problems. But they made very credible progress in considered steps. They searched the literature, talked to experts, and
collected material samples from various glass and polymer companies. They also worked on the
theories, and developed measurement techniques to carry out a host of experiments. They
developed an instrument to measure the spectral loss of very low-loss material, as well as one for scaled simulation experiments to measure fiber loss due to mechanical imperfections.
Charles zeroed in on glass as a possible transparent material. Glass is made from silica –
sand from centuries past that is plentiful and cheap.
The optical loss of transparent material is due to three mechanisms: (a) intrinsic absorption, (b)extrinsic absorption, and (c) Rayleigh scattering. The intrinsic loss is caused by the infrared absorption of the material structure itself, which determines the wavelength of the transparency
regions. The extrinsic loss is due to impurity ions left in the material and the Rayleigh loss is due to the scattering of photons by the structural non-uniformity of the material. For most practical applications such as windows, the transparency of glass was entirely adequate, and no one had
studied absorption down to such levels. After talking with many people, Charles eventually formed the following conclusions.
1. Impurities, particularly transition elements such as iron, copper, and manganese, have to be reduced to parts per million or even parts per billion. However, can impurity
concentrations be reduced to such low levels?
2. High temperature glasses are frozen rapidly and therefore are more homogeneous, leading to a lower scattering loss.
The ongoing microwave simulation experiments were also completed. The characteristics of
the dielectric waveguide were fully defined in terms of its modes, its dimensional tolerance both for end-to-end mismatch and for its diameter fluctuation along the fiber lengths. Both the theory and the simulated experiments supported the approach.
They wrote the paper entitled, ‘Dielectric-Fibre Surface Waveguides for Optical Frequencies’ and submitted it to the Proceedings of Institute of Electrical Engineers. After the usual review and revision, it appeared in July 1966 – the date now regarded as the birthday of optical
fiber communication.
4. The paper
The paper started with a brief discussion of the mode properties in a fiber of circular cross section.
The paper then quickly zeroed in on the material aspects, which were recognized to be the major stumbling block. At the time, the most transparent glass had a loss of 200 dB/km, which would limit transmission to about a few meters – this is very obvious to anyone who has ever peered through a thick piece of glass. Nothing can be seen.
But the paper pointed out that the intrinsic loss due to scattering could be as low as 1 dB/km,which would have allowed propagation over practical distances. The culprit is the impurities:
mainly ferrous and ferric ions at these wavelengths. Quoting from the paper: ‘It is foreseeable that glasses with a bulk loss of about 20 dB/km at around 0.6 micron will be obtained, as the iron-impurity concentration may be reduced to 1 part per million’. In layman terms, if one has a sufficiently ‘clean’ type of glass, one should be able to see through a slab as thick as several
hundred meters. That key insight opened up the field of optical communications.
The paper considered many other issues:
‧ The loss can be reduced if the mode is chosen so that most of the energy is actually
outside the fiber.
‧ The fiber should be surrounded by a cladding of lower index (which became the standard technology).
‧ The loss of energy due to bends in the fiber is negligible for bends larger than 1 mm.
‧ The losses due to non-uniform cross sections were estimated.
‧ The properties of a single-mode fiber (now a key technology especially for long distance and high data rate transmission) were analyzed. It was explained how dispersion limits bandwidth; an example was worked out for a 10 km route – a very bold scenario in 1966.
It may be appropriate to quote from the Conclusion of this paper:
The realization of a successful fiber waveguide depends, at present, on the availability of suitable low-loss dielectric material. The crucial material problem appears to be one which is difficult but not
impossible to solve. Certainly, the required loss figure of around 20 dB/km is much higher than the lower limit of loss figure imposed by fundamental mechanisms.
Basically all of the predictions pointed accurately to the paths of developments, and we now have 1/100 of the loss and 10,000 times the bandwidth then forecast – the evolutionary proposal in the 1966 paper was in hindsight too conservative.
5. Convincing the world
The substance of the paper was presented by Dr Kao at an IEE meeting in February 1966.
Most of the world did not take notice – except for the British Post Office (BPO) and the UK
Ministry of Defense, who immediately launched major research programs. By the end of 1966,
three groups in the UK were studying the various issues involved: Kao himself at STL; Roberts at BPO; Gambling at Southampton in collaboration with Williams at the Ministry of Defense Laboratory.
In the next few years, Dr Kao traveled the globe to push his idea: to Japan, where enduring friendships were made dating from those early days; to research labs in Germany, in the Netherlands and elsewhere to spread his news. He said that until more and more jumped on the bandwagon, the use of glass fibers would not take off. He had tremendous conviction in the face of widespread skepticism. The global telephony industry is huge, too large to be changed by a single
person or even a single country, but he was persistent and his enthusiasm was contagious, and slowly he converted others to be believers.
The experts at first proclaimed that the materials were the most severe of the intrinsic
insurmountable problems. Gambling wrote that British Telecom had been ‘somewhat scathing’
about the proposal earlier, and Bell Labs, who could easily have led the field, simply failed to take notice until the proven technology was pointed out to them. Dr Kao visited many glass
manufacturers to persuade them to produce the clear glass required. He got a response from
Corning, where Maurer led the first group that later produced the glass rods and developed the
techniques to make the glass fibers to the required specifications.
Meanwhile, Dr Kao continued to pour energy into proving the feasibility of glass fibers as
the medium for long-haul optical transmission. They faced a number of formidable challenges. The first was the measurement techniques for low-loss samples that were obtainable only in lengths of around 20 cm. The problem of assuring surface perfection was also ormidable. Another problem is end surface reflection loss, caused by the polishing process. They faced a measurement impasse that
demanded the detection of a loss difference between two samples of less than 0.1%, when the total
loss of the entire 20 cm sample is only 0.1%. An inexact measurement would be meaningless.
In 1968 and 1969, Dr Kao and his colleagues Davies, Jones and Wright at STL published a
series of papers on the attenuation measurements of glass that addressed the above problems. At that time, the measuring instruments called spectrophotometers had a rather limited sensitivity – in the
range of 43 dB/km. The measurement was very difficult: even a minute contamination could have caused a loss comparable to the attenuation itself, while surface effects could easily be ten times worse. Dr Kao and the team assembled a homemade single-beam spectrophotometer that achieved a
sensitivity of 21.7 dB/km. Later improvements with a double-beam spectrophotometer yielded a
sensitivity down to 4.3 dB/km.
The reflection effect was measured with a homemade ellipsometer. To make it, they used fused quartz samples made by plasma deposition, in which the high temperature evaporated the impurity ions. With the sensitive instrument, the attenuation of a number of glass samples was measured and,
eureka, the Infrasil sample from Schott Glass showed an attenuation as low as 5 dB/km at a window around 0.85 micron – at last proving that the removal of impurity would lower the absorption loss to useful levels.
This was really exciting because the low-loss region is right at the gallium-arsenide
laser emission band. The measurements clearly pointed the way to optical communication –
compact gallium-arsenide semiconductor lasers as the source, low-cost cladded glass fibers
as the transmission medium, and silicon or germanium semiconductors for detection. The
dream no longer seemed remote. These measurements apparently turned the sentiments of the research community around. The race to develop the first low-loss glass fiber waveguide was on.
In 1967, at Corning, Maurer’s chemist colleague Schultz helped to purify the glass.
In 1968, his colleagues Keck and Zimar helped to draw the fibers. By 1970, Corning had
produced a fiber waveguide with a loss of 17 dB/km at 0.633 micron using a
titanium-diffused core with silica cladding, using the Outside Vapor Deposition (OVD)
method. Two years later, they reduced the loss to 4 dB/km for a multimode fiber by
replacing the titanium-doped core with a germanium-doped core.
Bell Labs finally got on the bandwagon in 1969 and created a programme in optical
fiber research after having been skeptical for years. Their work on hollow light pipes was
finally stopped in 1972. Their millimeter wave research programme was wound down and
eventually abandoned in 1975.
It was during this time of constant flying out to other places that this cartoon joke hit home:‘Children, the man you see at the breakfast table today is your father!’
We saw him for a few days and off he went again. Sometimes he flew off for the day for
meetings at ITT Corp headquarters in New York. I would forget he had not left to go to the office and would phone his secretary to remind Charles to pick up milk or something on his way home.
His secretary was very amused:
‘Mrs Kao, don’t you know your husband is in New York today!’
6. Impact on the world
Since the deployment of the first-generation, 45-megabit-per-second fiber-optic
communication system in 1976, the transmission capacity in a single fiber has rapidly increased a million fold to tens of terabits per second. Data can be carried over millions of km of fibers without going through repeaters, thanks to the invention of the optical fiber amplifier and wavelength
division multiplexing. So that is how the industry grew and grew.
The world has been totally transformed because of optical fiber communication. The
telephone system has been overhauled and international long distance calls have become easily affordable.
Brand new mega-industries in fiber optics including cable manufacturing and equipment,
optical devices, network system and equipment have been created.
Hundreds of millions of kilometers of glass fiber cables have been laid, in the ground and in the ocean, creating an intricate web of connectivity that is the foundation of the world-wide web.
The Internet is now more pervasive than the telephone used to be. We browse, we skype, we
blog, we go onto you-tube, we shop, we socialize on-line. The information revolution that started in the 1990s could not have happened without optical fibers.
Over the last few years fibers are being laid all the way to our homes. All-optical networks
that are environmentally green are contemplated. The revolution in optical fiber communication has not ended – it might still just be at the beginning.
7. Conclusion
The world-wide communication network based on optical fibers has truly shrunk the world
and brought human beings closer together. I hardly need to cite technical figures to drive this point home. The news of the Nobel Prize reached us in the middle of the night at 3 am in California, through a telephone call from Stockholm (then in their morning) no doubt carried on optical fibers; congratulations came literally minutes later from friends in Asia (for whom it was evening), again
through messages carried on optical fibers. Too much information is not always a good thing: we had to take the phone off the hook that night in order to get some sleep!
Optical communication is by now not just a technical advance, but has also caused major
changes in society. The next generation will learn and grow up differently; people will relate to one another in different ways. Manufacturing of all the bits and pieces of a single product can now take place over a dozen locations around the world, providing huge opportunities for people especially in
developing countries. The wide accessibility of information has obviously led to more equality and wider participation in public affairs.
Many words, indeed many books have been written about the information society, and I do
not wish to add to them here – except to say that it is beyond the dreams of the first serious concept of optical communication in 1966, when even 1 GHz was only a hope.
In conclusion, Charles and I want to thank the Professors at The Chinese University of Hong
Kong, namely: Professor Young, Professor Wong, Professor Cheung and Professor Chen for their
support in compiling this lecture for us. Charles would like to thank ITT Corp where he developed his career for 30 years and all those who climbed on to the bandwagon with him in the early days, as without the legions of believers the industry would not have evolved as it did.
Charles Kao planted the seed; Bob Maurer watered it and John MacChesney grew its roots.
Send future voices fast.
A Nobel Lecture
organized by the Royal Swedish Academy of Sciences
and
The Prize Committee in Physics
delivered by
Mrs Gwen MW Kao
on behalf of
Prof Charles K Kao
Nobel Laureate in Physics 2009
8 December 2009
Aula Magna
Stockholm University
1. Introduction
It is sad that my husband, Professor Charles Kao, is unable to give this lecture to you
himself. As the person closest to him, I stand before you to honour him and to speak for him. He is very very proud of his achievements for which the Nobel Foundation honours him. As are we all!
In the 43 years since his seminal paper of 1966 that gave birth to the ubiquitous glass fiber cables of today, the world of telephony has changed vastly. It is due to Professor Kao’s persistence in the face of skepticism that this revolution has occurred.
In the 1970s the pre-production stage moved to ITT Corp Roanoke VA, USA. Whilst Charles worked there, he received two letters. One contained a threatening message accusing him of
releasing an evil genie from its bottle; the other, from a farmer in China, asked for a means to allow him to pass a message to his distant wife to bring his lunch. Both letter writers saw a future that has since become past history.
In the 1960s, our children were small. Charles often came home later than normal – dinner
was waiting as were the children. I got very annoyed when this happened day after day. His words,maybe not exactly remembered, were –
‘Please don’t be so mad. It is very exciting what we are doing; it will shake the world one day!’
I was sarcastic, ‘Really, so you will get the Nobel Prize, won’t you!
He was right – it has revolutionized telecommunications.
2. The early days
In 1960, Charles joined Standard Telecommunications Laboratories Ltd. (STL), a subsidiary of ITT Corp in the UK, after having worked as a graduate engineer at Standard Telephones and Cables in Woolwich for some time. Much of the work at STL was devoted to improving the capabilities of the existing communication infrastructure with a focus on the use of millimeter wave transmission systems.
Millimeter waves at 35 to 70 GHz could have a much higher transmission capacity. But the
waters were uncharted and the challenges enormous, since radio waves at such frequencies could not be beamed over long distances due to beam divergence and atmospheric absorption. The waves
had to be guided by a waveguide. And in the 1950’s, R&D work on low loss circular
waveguides –HE-11 mode – was started. A trial system was deployed in the 1960s. Huge sums were invested, and more were planned, to move this system into the pre-production stage. Public expectation for new telecommunication services such as the video phone had heightened.
Charles joined the long-haul waveguide group led by Dr Karbowiak at STL. He was excited
to see an actual circular waveguide. He was assigned to look for new transmission methods for microwave and optical transmission. He used both ray optics and wave theory to gain a better understanding of waveguide problems – then a novel idea. Later, his boss encouraged him to pursue a doctorate while working at STL. So Charles registered at University College London and completed the dissertation ‘Quasi-Optical Waveguides’ in two years.
The invention of the laser in 1959 gave the telecom community a great dose of optimism
that optical communication could be just around the corner. The coherent light was to be the new information carrier with capacity a hundred thousand times higher than point-to-point microwaves –based on the simple comparison of frequencies: 300 terahertz for light versus 3 gigahertz for microwaves.
The race between circular microwave waveguides and optical communication was on, with
the odds heavily in favour of the former. In 1960, optical lasers were in their infancy, demonstrated at only a few research laboratories, and performing much below the needed specs. Optical systems seemed a non-starter.
But Charles still thought the laser had potential. He said to himself: ‘How can we
dismiss the laser so readily? Optical communication is too good to be left on the theoretical shelf.’
He asked himself the obvious questions:
1. Is the ruby laser a suitable source for optical communication?
2. What material has sufficiently high transparency at such wavelengths?
At that time only two groups in the world were starting to look at the transmission aspect of
optical communication, while several other groups were working on solid state and semiconductor lasers. Lasers emit coherent radiation at optical frequencies, but using such radiation for communication appeared to be very difficult, if not impossible. For optical communication to fulfill its promises, many serious problems remained to be solved.
3. The key discovery
In 1963 Charles was already involved in free space propagation experiments: the rapid
progress of semiconductor and laser technology had opened up a broader scope to explore optical communication realistically. With a helium-neon laser beam directed to a spot some distance away, the STL team quickly discovered that distant laser light flickered. The beam danced around several beam diameters because of atmospheric fluctuations.
The team also tried to repeat experiments done by other research laboratories around the
world. For example, they set up con-focal lens experiments similar to those at Bell Labs: a series of convex lenses were lined up at intervals equal to the focal length. But even at the dead of night when the air was still and even with refocusing every 100 meters, the beam refused to stay within the lens aperture.
Bell Labs experiments using gas lenses were abandoned due to the difficulty of providing
satisfactory insulation while maintaining the profiles of the gas lenses. These experiments were struggles in desperation, to control light travelling over long distances.
At STL the thinking shifted towards dielectric waveguides. Dielectric means a non-conductor of electricity; a dielectric waveguide is a waveguide consisting of a dielectric
cylinder surrounded by air. Dr Karbowiak suggested Charles and three others to work on his idea of a thin film waveguide.
But thin film waveguides failed: the confinement was not strong enough and light would escape as it negotiates a bend.
When Dr Karbowiak decided to emigrate to Australia, Charles took over as the project
leader and he then recommended that the team should investigate the loss mechanism of dielectric materials for optical fibers.
A small group worked on methods for measuring material loss of low-loss transparent
materials. George Hockham joined him to work on the characteristics of dielectric waveguides.
With his interest in waveguide theory, he focused on the tolerance requirements for an optical fiber waveguide; in particular, the dimensional tolerance and joint losses. They proceeded to systematically study the physical and waveguide requirements on glass fibers.
In addition, Charles was also pushing his colleagues in the laser group to work towards a
semiconductor laser in the near infrared, with emission characteristics matching the diameter of a single-mode fiber. Single mode fiber is optical fiber that is designed for the transmission of a single ray or mode of light as a carrier. The laser had to be made durable, and to work at room temperatures without liquid nitrogen cooling. So there were many obstacles. But in the early 1960s,
esoteric research was tolerated so long as it was not too costly.
Over the next two years, the team worked towards the goals. They were all novices in the
physics and chemistry of materials and in tackling new electromagnetic wave problems. But they made very credible progress in considered steps. They searched the literature, talked to experts, and
collected material samples from various glass and polymer companies. They also worked on the
theories, and developed measurement techniques to carry out a host of experiments. They
developed an instrument to measure the spectral loss of very low-loss material, as well as one for scaled simulation experiments to measure fiber loss due to mechanical imperfections.
Charles zeroed in on glass as a possible transparent material. Glass is made from silica –
sand from centuries past that is plentiful and cheap.
The optical loss of transparent material is due to three mechanisms: (a) intrinsic absorption, (b)extrinsic absorption, and (c) Rayleigh scattering. The intrinsic loss is caused by the infrared absorption of the material structure itself, which determines the wavelength of the transparency
regions. The extrinsic loss is due to impurity ions left in the material and the Rayleigh loss is due to the scattering of photons by the structural non-uniformity of the material. For most practical applications such as windows, the transparency of glass was entirely adequate, and no one had
studied absorption down to such levels. After talking with many people, Charles eventually formed the following conclusions.
1. Impurities, particularly transition elements such as iron, copper, and manganese, have to be reduced to parts per million or even parts per billion. However, can impurity
concentrations be reduced to such low levels?
2. High temperature glasses are frozen rapidly and therefore are more homogeneous, leading to a lower scattering loss.
The ongoing microwave simulation experiments were also completed. The characteristics of
the dielectric waveguide were fully defined in terms of its modes, its dimensional tolerance both for end-to-end mismatch and for its diameter fluctuation along the fiber lengths. Both the theory and the simulated experiments supported the approach.
They wrote the paper entitled, ‘Dielectric-Fibre Surface Waveguides for Optical Frequencies’ and submitted it to the Proceedings of Institute of Electrical Engineers. After the usual review and revision, it appeared in July 1966 – the date now regarded as the birthday of optical
fiber communication.
4. The paper
The paper started with a brief discussion of the mode properties in a fiber of circular cross section.
The paper then quickly zeroed in on the material aspects, which were recognized to be the major stumbling block. At the time, the most transparent glass had a loss of 200 dB/km, which would limit transmission to about a few meters – this is very obvious to anyone who has ever peered through a thick piece of glass. Nothing can be seen.
But the paper pointed out that the intrinsic loss due to scattering could be as low as 1 dB/km,which would have allowed propagation over practical distances. The culprit is the impurities:
mainly ferrous and ferric ions at these wavelengths. Quoting from the paper: ‘It is foreseeable that glasses with a bulk loss of about 20 dB/km at around 0.6 micron will be obtained, as the iron-impurity concentration may be reduced to 1 part per million’. In layman terms, if one has a sufficiently ‘clean’ type of glass, one should be able to see through a slab as thick as several
hundred meters. That key insight opened up the field of optical communications.
The paper considered many other issues:
‧ The loss can be reduced if the mode is chosen so that most of the energy is actually
outside the fiber.
‧ The fiber should be surrounded by a cladding of lower index (which became the standard technology).
‧ The loss of energy due to bends in the fiber is negligible for bends larger than 1 mm.
‧ The losses due to non-uniform cross sections were estimated.
‧ The properties of a single-mode fiber (now a key technology especially for long distance and high data rate transmission) were analyzed. It was explained how dispersion limits bandwidth; an example was worked out for a 10 km route – a very bold scenario in 1966.
It may be appropriate to quote from the Conclusion of this paper:
The realization of a successful fiber waveguide depends, at present, on the availability of suitable low-loss dielectric material. The crucial material problem appears to be one which is difficult but not
impossible to solve. Certainly, the required loss figure of around 20 dB/km is much higher than the lower limit of loss figure imposed by fundamental mechanisms.
Basically all of the predictions pointed accurately to the paths of developments, and we now have 1/100 of the loss and 10,000 times the bandwidth then forecast – the evolutionary proposal in the 1966 paper was in hindsight too conservative.
5. Convincing the world
The substance of the paper was presented by Dr Kao at an IEE meeting in February 1966.
Most of the world did not take notice – except for the British Post Office (BPO) and the UK
Ministry of Defense, who immediately launched major research programs. By the end of 1966,
three groups in the UK were studying the various issues involved: Kao himself at STL; Roberts at BPO; Gambling at Southampton in collaboration with Williams at the Ministry of Defense Laboratory.
In the next few years, Dr Kao traveled the globe to push his idea: to Japan, where enduring friendships were made dating from those early days; to research labs in Germany, in the Netherlands and elsewhere to spread his news. He said that until more and more jumped on the bandwagon, the use of glass fibers would not take off. He had tremendous conviction in the face of widespread skepticism. The global telephony industry is huge, too large to be changed by a single
person or even a single country, but he was persistent and his enthusiasm was contagious, and slowly he converted others to be believers.
The experts at first proclaimed that the materials were the most severe of the intrinsic
insurmountable problems. Gambling wrote that British Telecom had been ‘somewhat scathing’
about the proposal earlier, and Bell Labs, who could easily have led the field, simply failed to take notice until the proven technology was pointed out to them. Dr Kao visited many glass
manufacturers to persuade them to produce the clear glass required. He got a response from
Corning, where Maurer led the first group that later produced the glass rods and developed the
techniques to make the glass fibers to the required specifications.
Meanwhile, Dr Kao continued to pour energy into proving the feasibility of glass fibers as
the medium for long-haul optical transmission. They faced a number of formidable challenges. The first was the measurement techniques for low-loss samples that were obtainable only in lengths of around 20 cm. The problem of assuring surface perfection was also ormidable. Another problem is end surface reflection loss, caused by the polishing process. They faced a measurement impasse that
demanded the detection of a loss difference between two samples of less than 0.1%, when the total
loss of the entire 20 cm sample is only 0.1%. An inexact measurement would be meaningless.
In 1968 and 1969, Dr Kao and his colleagues Davies, Jones and Wright at STL published a
series of papers on the attenuation measurements of glass that addressed the above problems. At that time, the measuring instruments called spectrophotometers had a rather limited sensitivity – in the
range of 43 dB/km. The measurement was very difficult: even a minute contamination could have caused a loss comparable to the attenuation itself, while surface effects could easily be ten times worse. Dr Kao and the team assembled a homemade single-beam spectrophotometer that achieved a
sensitivity of 21.7 dB/km. Later improvements with a double-beam spectrophotometer yielded a
sensitivity down to 4.3 dB/km.
The reflection effect was measured with a homemade ellipsometer. To make it, they used fused quartz samples made by plasma deposition, in which the high temperature evaporated the impurity ions. With the sensitive instrument, the attenuation of a number of glass samples was measured and,
eureka, the Infrasil sample from Schott Glass showed an attenuation as low as 5 dB/km at a window around 0.85 micron – at last proving that the removal of impurity would lower the absorption loss to useful levels.
This was really exciting because the low-loss region is right at the gallium-arsenide
laser emission band. The measurements clearly pointed the way to optical communication –
compact gallium-arsenide semiconductor lasers as the source, low-cost cladded glass fibers
as the transmission medium, and silicon or germanium semiconductors for detection. The
dream no longer seemed remote. These measurements apparently turned the sentiments of the research community around. The race to develop the first low-loss glass fiber waveguide was on.
In 1967, at Corning, Maurer’s chemist colleague Schultz helped to purify the glass.
In 1968, his colleagues Keck and Zimar helped to draw the fibers. By 1970, Corning had
produced a fiber waveguide with a loss of 17 dB/km at 0.633 micron using a
titanium-diffused core with silica cladding, using the Outside Vapor Deposition (OVD)
method. Two years later, they reduced the loss to 4 dB/km for a multimode fiber by
replacing the titanium-doped core with a germanium-doped core.
Bell Labs finally got on the bandwagon in 1969 and created a programme in optical
fiber research after having been skeptical for years. Their work on hollow light pipes was
finally stopped in 1972. Their millimeter wave research programme was wound down and
eventually abandoned in 1975.
It was during this time of constant flying out to other places that this cartoon joke hit home:‘Children, the man you see at the breakfast table today is your father!’
We saw him for a few days and off he went again. Sometimes he flew off for the day for
meetings at ITT Corp headquarters in New York. I would forget he had not left to go to the office and would phone his secretary to remind Charles to pick up milk or something on his way home.
His secretary was very amused:
‘Mrs Kao, don’t you know your husband is in New York today!’
6. Impact on the world
Since the deployment of the first-generation, 45-megabit-per-second fiber-optic
communication system in 1976, the transmission capacity in a single fiber has rapidly increased a million fold to tens of terabits per second. Data can be carried over millions of km of fibers without going through repeaters, thanks to the invention of the optical fiber amplifier and wavelength
division multiplexing. So that is how the industry grew and grew.
The world has been totally transformed because of optical fiber communication. The
telephone system has been overhauled and international long distance calls have become easily affordable.
Brand new mega-industries in fiber optics including cable manufacturing and equipment,
optical devices, network system and equipment have been created.
Hundreds of millions of kilometers of glass fiber cables have been laid, in the ground and in the ocean, creating an intricate web of connectivity that is the foundation of the world-wide web.
The Internet is now more pervasive than the telephone used to be. We browse, we skype, we
blog, we go onto you-tube, we shop, we socialize on-line. The information revolution that started in the 1990s could not have happened without optical fibers.
Over the last few years fibers are being laid all the way to our homes. All-optical networks
that are environmentally green are contemplated. The revolution in optical fiber communication has not ended – it might still just be at the beginning.
7. Conclusion
The world-wide communication network based on optical fibers has truly shrunk the world
and brought human beings closer together. I hardly need to cite technical figures to drive this point home. The news of the Nobel Prize reached us in the middle of the night at 3 am in California, through a telephone call from Stockholm (then in their morning) no doubt carried on optical fibers; congratulations came literally minutes later from friends in Asia (for whom it was evening), again
through messages carried on optical fibers. Too much information is not always a good thing: we had to take the phone off the hook that night in order to get some sleep!
Optical communication is by now not just a technical advance, but has also caused major
changes in society. The next generation will learn and grow up differently; people will relate to one another in different ways. Manufacturing of all the bits and pieces of a single product can now take place over a dozen locations around the world, providing huge opportunities for people especially in
developing countries. The wide accessibility of information has obviously led to more equality and wider participation in public affairs.
Many words, indeed many books have been written about the information society, and I do
not wish to add to them here – except to say that it is beyond the dreams of the first serious concept of optical communication in 1966, when even 1 GHz was only a hope.
In conclusion, Charles and I want to thank the Professors at The Chinese University of Hong
Kong, namely: Professor Young, Professor Wong, Professor Cheung and Professor Chen for their
support in compiling this lecture for us. Charles would like to thank ITT Corp where he developed his career for 30 years and all those who climbed on to the bandwagon with him in the early days, as without the legions of believers the industry would not have evolved as it did.
Charles Kao planted the seed; Bob Maurer watered it and John MacChesney grew its roots.
【明報專訊】亨利 的「上帝之手」令法國 出線世盃決賽周，亦為法國帶來龐大經濟效益。有專家指出，出線世盃能為法國這種規模的國家，帶來約128億港元的經濟效益。英國 考文垂大學的運動商業策略教授查德威克（Simon Chadwick）說：「這將在直接受惠的行業中引起漣漪作用，像是體育博彩及雜誌出版……漣漪作用甚至將遠至電器零售及生產，因為人們在大賽時傾向買更多電視。這是心理因素——運動上的成功令人們感到更樂觀及更易買東西」。
愛爾蘭 經濟損失13億
相比下，亨利的「上帝之手」則重挫了愛爾蘭經濟。愛爾蘭的衰退本已是歐洲最嚴重，分析師魯姆斯（Owen James）說，今次無緣出線，「若根據家庭開支數字及其他因素，我估計愛爾蘭經濟將損失1億鎊（約12.8億港元）。」巴克萊銀行的波茨（Henk Potts）則說：「零售業和酒吧娛樂事業收入將受挫。在國家隊作賽前，超市一些產品的銷量總會上升，博彩商亦會預期，若愛爾蘭入圍，將有更多（賭博）活動」。
亨利上帝之手惡搞照片則在網上熱傳。不少愛爾蘭及外國球迷都不滿他出術而紛紛為他改相。Facebook上就成立了群組，要求「將法國踢出明年南非世界盃 」。
每日郵報
【明報專訊】甲型H1N1流感（新型流感）在內地的疫情不斷升級，但官方公布的死亡數字迄今僅53人，內地著名傳染病專家鍾南山質疑內地個別地區隱瞞死亡數字，明言「根本不信」國家官方公布死亡個案數據。國家衛生部 昨晚回應稱，嚴禁各地瞞報、謊報及緩報新型流感疫情及死亡病例。
香港大學 微生物學教授管軼同意鍾南山的看法。他指出，香港有700萬人，迄今也有40人因染新型流感死亡，按人口比例推算，7000萬人口的地方約有400人死，7億人口地方約有4000人死，中國有13億人口，即使內地感染新型流感的死亡率低於香港10倍，至少也總有數百人染病死亡，但內地官方公布只得53人染上新流病死亡，人數低得不合理。
「不檢測不報告 後果嚴重」
踏入10月中開始，內地新型流感患者人數激增。鍾南山日前接受廣州傳媒訪問時表示，北方已進入甲流第二波，南方的第二波高峰預計明年1至2月份殺到。鍾南山多次提及內地個別地區為表示當地防控工作做得好，隱瞞不報甲流死亡病例，他說，「最反感重症甲流患者死亡後，既不檢測也不報告的做法，這絕對招來更嚴重的後果」，他直言﹕「現在全國報告的甲流死亡病例數，我根本不信！」
他強調，瞞報可能會令外界未能及時察覺病毒有否變異，導致更嚴重的後果。鍾南山引述中國工程院有關專家預測，在流感高峰期，內地會有一至兩成人口，即約1.3億至2.6億人染疫，當中800萬到1700萬患者需要住院。
世衛﹕內地公布「最小數字」
世界衛生組織 （WHO）駐中國首席代表Michael O'Leary日前對美聯社表示，中國新型流感染病個案顯著增長，當局公布的只是「最小的數字」﹕「死亡人數往往超出我們所知的。」
衛生部﹕派員全國檢查防控
國家衛生部表示，會嚴格執行新型流感疫情報告制度，近日衛生部已派出9個工作組往全國12個省檢查當地防控工作，各地若有瞞報、漏報、緩報新型流感死亡或感染病例，有關人員會被追究責任。
2003年SARS 疫情大爆發時，內地曾瞞報情况，後來因退休軍醫蔣彥勇向上級報告，並向內地傳媒反映不果，率先向外國傳媒揭露中國疫情之嚴重，當局才承認瞞報，免去衛生部長張文康和北京 市長孟學農之職。
長居粵 港心臟病 漢染疫亡
另外，本港衛生防護中心 接獲廣東省衛生廳通報，指一名56歲香港市民本月初在廣州感染新型流感，在當地治療10多天，於周日（15日）不治死亡。該男子長期患心臟病，居住廣州已數年，最近並無返港紀錄，其同住太太未被傳染。
《货币战争》作者谈中美汇率之争
宋鸿兵：我看到三组关键字，贸易、汇率、财富的问题。我是这么理解这三组关键字的概念，贸易战背后打的实际是汇率之争，而汇率之争最后涉及到的是整个国家财富重新 分配的问题。汇率问题不单纯是市场决定的普通的市场的元素，它更主要体现在它是一种制度安排，和国家与国家之间的财富分配达成的一种默契和妥协。从这个角度来讲，每当 美国指责中国是最大汇率国的时候，其实我们应该看到，美国所发行的美元才是真正的最大的操纵的力量。由于美国所发行的美元是世界上最大的结算货币和筹备货币，它在发行 的过程中不受任何人的监管，没有任何国际组织能够制约它，最大债权国美国也不能制约它。
水均益：它一高兴就多印票子，缩水，你手里拿着它的美元还贬值。
宋鸿兵：对，甚至连美国国会都说，在金融海啸治理过程中，6.8万亿担保怎么花的，国会都无缘去查它的账，在这种情况下，它所印的海量印刷钞票导致了全世界各个国家货 币体系的紊乱，大家只是被迫做自己的相适应的调整。这个时候它却反而说其他国家包括中国是汇率操纵国，我觉得最大的汇率操纵国应该是美国自己。
【明報專訊】有「網絡奧斯卡 」之稱的韋比獎（Webby Awards），周三評選出10年來互聯網十大最重要時刻，網上自由百科全書維基的推出、iPhone登場，以及社交網站Facebook及Twitter發揮巨大威力，均告榜上有名。
韋比獎由紐約 國際數碼藝術與科學學院主辦，至今已舉辦了13年，每年都會評選出一系列獎項。韋比獎總監戴維斯說﹕「互聯網之所以成為這10年間一大重要現象，是因為它不僅改變我們的日常生活，還改變了商業、通訊、政治和流行文化等領域。」以下為韋比獎選出的互聯網十大重要時刻﹕
￭美國 分類廣告網Craigslist
服務擴至三藩市 以外（2000年）
當年Craigslist免費分類廣告網站的服務範圍，擴至美國其他9個城市，大大衝擊傳統報章分類廣告形式。迄今Craigslist在全球50多國家逾500個城市開展業務。
￭Google推出AdWords廣告平台（2000年）
用戶只要鍵入相關產品的關鍵字，搜尋網頁便會展示相關廣告，令廣告商可更準確地找到潛在顧客，掀起網上廣告革命。
￭維基百科 （2001年）
由全球網民參與編輯的它，至今已上載超過1400萬篇文章，共有271種不同語言。
■檔案分享網站Napster關閉（2001年）
90年代末，Napster曾以提供盜版音樂下載而為人熟悉，在各大唱片公司打壓下，Napster於2001年關閉。它的關閉，催生了蘋果iTunes及其他合法音樂服務網站的出現。
■Google首次公開招股（2004年）
Google公開招股後，業務益趨多元化，除核心搜尋業務，還推出Gmail、Google地圖、Android手機作業系統等。
￭網上視頻變革（2006年）
隨著YouTube 等短片網站出現，增加了大量由用戶自製的短片內容。
￭Facebook用戶增加及Twitter興起（2006年）
Facebook當年宣布，任何13歲以上的網民都可成為用戶，令其用戶數目大增。Twitter隨後亦開展服務。
￭iPhone登場（2007年）
iPhone在2007年7月29日正式推出，一周內其銷量達50萬部，掀起全球手機革命。
■互聯網在美國大選發揮重要作用（2008年）
網上論壇和社交網站成了總統候選人跟美國網民交流的重要地方。
￭伊朗 大選民眾廣泛使用Twitter抗爭（2009年）
Twitter用戶在網上號召民眾示威，又發布當局鎮壓民眾消息。
法新社/有線 新聞網絡
西方醫學界有一個長期疑問，究竟安慰劑效果是否存在? 即不具醫學作用的用品，例如維他命，能否在病人不知情的安排下，產生心理作用，變成具體療效。
美國學者丹艾瑞里做了兩個極具參考的實驗，答案差不多是肯定存在安慰劑效果。
實驗很簡單，利用一些維生素，提供給病人，然後再讓病人接受電擊，說吃過藥後，可以減輕痛楚。
結果一如所料，有九成二病人，在服藥10分鐘之內，認為有效減輕痛楚。
但最有趣的部份，是他們有第二組實驗，這一組病人，得悉藥丸的價錢，只及原來藥品的五分之二，結果又有沒有差異呢?
有。一如所料，認為這些維生素有效有人大幅減少，只有一半。
丹艾瑞里的結論就是，人們往往依賴一些非理性的直覺作判斷，但這些判斷，又往往反過來變成事實。而進一步的研究又發現，醫生對一種治療方案是否熱心，很大程度能影響實際療效。
丹艾瑞里認為，這方面的研究，至今遠遠不足，要繼續努力，但基本原則，不應該是無休止的做實驗。
