Two Revolutionary Optical Technologies: "for groundbreaking achievements concerning the transmission of light in fibers for optical communication" + "for the invention of an imaging semiconductor circuit – the CCD sensor"
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Question for online poll on the sidelines of this year`s Physics Nobel announcements was asked is this: “Did you know that this question comes to you via glass fibre?” The mere words reflecting the kind of revolutionary character the invention Charles K. Kao gifted to this world ! He initiated search for and the development of the low-loss optical fiber presently used in optical fiber communication systems. On the other hand ‘The Sailer Man’ George E. Smith who submitted thesis of three pages to University of Chicago says that ideas of the charged couple devices actually came from his head when he was deleivering one lecture on invention. He even don`t remember exactly how many patents he held with his colleague Willard S. Boyle at Bell Labs in 60s , 70s, 80s. Willard S. Boyle and George E. Smith invented the charge-coupled device (CCD) presently used in many digital cameras and in advanced medical and scientific instrumentation.These three who are recipient of this year`s Physics Nobel are the people who are responsible for shaping modern information technology to present stage. Kao’s discoveries have paved the way for optical fiber technology, which today is used for almost all telephony and data communication. Boyle and Smith have invented a digital image sensor – CCD, or charge-coupled device – which today has become an electronic eye in almost all areas of photography.
Underlying the historical feature of the Kao`s work Nobel Foundation says, “When the Nobel Prize in Physics is announced in Stockholm, a large part of the world receives the message almost instantly. At almost the speed of light, the highest of speeds, the message is spread around the world. Text, images, speech and video are shuffled around in optical fibers and through space, and are received instantly in small and convenient devices. It is something that many people have already come to take for granted. The optical fiber has been a prerequisite for this extremely rapid development in the field of communications, a development that Charles Kao predicted over 40 years ago.”
Kao worked for Standard Telecommunication Laboratories Harlow, United Kingdom and Chinese University of Hong Kong. Charles K. Kao was a young engineer at STL working on optical communication. Kao was born in 1933 in Shanghai, China, educated in Hong-Kong and graduated in Electrical Engineering in 1957 at University of London and got a PhD at the University of London in 1965. With the help of colleague Hockham whose work on the analysis of the effect of waveguide imperfections lead them to a thesis defended in 1969. They investigated in detail the fundamental properties of optical fibers with respect to optical communication.
Just around that time, Willard Boyle and George Smith radically altered the conditions for the field of photography, because film is no longer needed in cameras where the images can be captured electronically with an image sensor. The electronic eye, the CCD, became the first truly successful technology for the digital transfer of images. It opened the door to a daily stream of images, which is filling up the optical fiber cables. Only optical fiber is capable of transferring such large quantities of data that electronic image sensor technology yields.
100 years ago, G. Marconi and K.F. Braun were awarded the Nobel prize “in recognition of their contributions to the development of wireless telegraphy”. 50 years ago, electronic and radio communications were in rapid expansion. The first transatlantic cable was installed in 1956 and satellites would soon allow even better coverage. The first communication satellite was launched in 1958. Research in telecommunication concentrated mainly in shorter radio waves, in the millimeter range, with the aim to reach higher transmission speeds. These waves could not travel as easily in air as longer waves, and the research focused on designing practical waveguides. The invention of the laser in the early 1960s (Nobel Prize in 1964 to C.H. Townes, N.G. Basov and A.M. Prokhorov) gave a new boost to the research in optical communication. 1 Previous use of optical fibres was limited to medical use for industrial manufacturing of instruments for gastroscopy and other medical uses.
Global communication, and in particular internet and long-distance telephony, is now based primarily on optical fiber technology. The main advantage of optical waves compared to radio waves is the high frequencies that allow high data transmission rate. Nowadays, several terabits per second can be transmitted in a single fiber which represents an increase by a factor of one million to what could be achieved fifty years ago with radio signal transmission. The number of optical fiber cables being installed all over the world is increasing rapidly. Fiber optics has also been important for a huge number of other applications, in medicine, laser technology and sensors.
Different schemes for color photography were also explored during the 19th century. G. Lippman was awarded the 1908 Nobel Prize in Physics for his color photographic process based on interference effects. W.H.F. Talbot invented in 1841, thus initiating modern photography, light sensitive papers containing silver salts for first obtaining a negative image and thereafter, through contact copying with another light sensitive paper, a positive image. He described also the steps necessary to develop the latent images formed in the papers. Several developments followed regarding the substrate used for the light sensitive layers. The idea to use emulsions (silver salts in gelatin) to create negatives was conceived around 1870 and the replacement of glass plates with a celluloid film around 1880. The roll of film was invented 1887 by a priest, H. Goodwin, and explored by G. Eastman. In 1888 the Eastman Kodak box camera for roll film appeared on the market. Different schemes for color photography were also explored during the 19th century. G. Lippman was awarded the 1908 Nobel Prize in Physics for his color photographic process based on interference effects.
Willard S. Boyle and George E. Smith were both at Bell Laboratories, New Jersey when they conceived the CCD device. The CCD is a metal-oxide semiconductor (MOS) device that can be used as a detector to record images in electronic form, and thus it offers a modern alternative to the photographic film. A CCD can record a scene by accumulating light induced charges over its semiconductor surface, and by transporting them to be read out at the edge of the light sensitive area. The invention utilized the properties of the then new MOS (Metal Oxide Semiconductor) technology to create an integrated and simple device to record and read out a scene. The read-out is similar to a fashion often referred to as a “bucket brigade” as it shifts arrays of information by successive site shift.
The hour long discussion between Boyle and Smith in 1969 led to an enormous development of practical and scientific instrumentation based on CCDs: digital cameras, medical devices and high performance scientific instrumentation, not least for astronomy and astrophysics. There are several important medical applications for CCD cameras, e.g. for the study of tissues and cells as imaging devices in microscopes or for the recording of cells and tissue. Digital photography has also revolutionized almost all image based medical diagnostic tools. A large application is found in endoscopy for inspections inside the body and for guidance during micro- or ‘key hole’- surgery. There are many types of endoscopes, e.g. based on single optical fibers, optical fiber bundles or in the form of capsules possible to swallow with built in light source, CCD sensors and wireless signal transmission.
Solid-state image sensors and digital cameras have changed the role of images in our society, since they give electronic signals, digits, which can easily be transmitted and treated. In science, the possibility of transferring and processing images digitally is a real revolution. Digital image processing is now a global commodity which enables, for instance, the best international expertise to be involved in crucial diagnostic and even surgical situations, through remote control and feedback through digital cameras. Furthermore the evaluation of large amounts of data (e.g. created in mapping the universe) can be spread to many groups and even to volunteers from the general public; and no doubt this dissemination will take place of course due to the grace of Optical Fibres invented by Dr. Kao.
1 THE ROYAL SWEDISH ACADEMY OF SCIENCES, Scientific Background on the Nobel Prize in Physics 2009, TWO REVOLUT IONARY OPTICAL TECHNOLOGIES, 6 October 2009
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