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1917 |
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Theory of stimulated emission
Albert Einstein proposes the theory of stimulated emission—that is, if an atom in a high-energy state is stimulated by a photon of the right wavelength, another photon of the same wavelength and direction of travel will be created. Stimulated emission will form the basis for research into harnessing photons to amplify the energy of light.
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1954 |
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"Maser" developed
Charles Townes, James Gordon, and Herbert Zeiger at Columbia University develop a "maser" (for microwave amplification by stimulated emission of radiation), in which excited molecules of ammonia gas amplify and generate radio waves. The work caps 3 years of effort since Townes's idea in 1951 to take advantage of high-frequency molecular oscillation to generate short-wavelength radio waves.
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1958 |
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Concept of a laser introduced
Townes and physicist Arthur Schawlow publish a paper showing that masers could be made to operate in optical and infrared regions. The paper explains the concept of a laser (light amplification by stimulated emission of radiation)—that light reflected back and forth in an energized medium generates amplified light.
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1960 |
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Operable laser invented
Theodore Maiman, a physicist and electrical engineer at Hughes Research Laboratories, invents an operable laser using a synthetic pink ruby crystal as the medium. Encased in a "flash tube" and book ended by mirrors, the laser successfully produces a pulse of light. Prior to Maiman’s working model, Columbia University doctoral student Gordon Gould also designs a laser, but his patent application is initially denied. Gould finally wins patent recognition nearly 30 years later.
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1960 |
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Continuously operating helium-neon gas laser invented
Bell Laboratories researcher and former Townes student Ali Javan and his colleagues William Bennett, Jr., and Donald Herriott invent a continuously operating helium-neon gas laser. The continuous beam of laser light is extracted by placing parallel mirrors on both ends of an apparatus delivering an electrical current through the helium and neon gases. On December 13, Javan experiments by holding the first telephone conversation ever delivered by a laser beam.
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1961 |
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Glass fiber demonstration
Industry researchers Elias Snitzer and Will Hicks demonstrate a laser beam directed through a thin glass fiber. The fiber’s core is small enough that the light follows a single path, but most scientists still consider fibers unsuitable for communications because of the high loss of light across long distances.
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1961 |
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First medical use of the ruby laser
In the first medical use of the ruby laser, Charles Campbell of the Institute of Ophthalmology at Columbia- Presbyterian Medical Center and Charles Koester of the American Optical Corporation use a prototype ruby laser photocoagulator to destroy a human patient’s retinal tumor.
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1962 |
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Gallium arsenide laser developed
Three groups—at General Electric, IBM, and MIT’s Lincoln Laboratory—simultaneously develop a gallium arsenide laser that converts electrical energy directly into infrared light and that much later is used in CD and DVD players as well as computer laser printers.
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1963 |
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Heterostructures
Physicist Herbert Kroemer proposes the idea of heterostructures, combinations of more than one semiconductor built in layers that reduce energy requirements for lasers and help them work more efficiently. These heterostructures will later be used in cell phones and other electronic devices.
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1966 |
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Landmark paper on optical fiber
Charles Kao and George Hockham of Standard Telecommunications Laboratories in England publish a landmark paper demonstrating that optical fiber can transmit laser signals with much reduced loss if the glass strands are pure enough. Researchers immediately focus on ways to purify glass.
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1970 |
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Optical fibers that meet purity standards
Corning Glass Works scientists Donald Keck, Peter Schultz, and Robert Maurer report the creation of optical fibers that meet the standards set by Kao and Hockham. The purest glass ever made, it is composed of fused silica from the vapor phase and exhibits light loss of less than 20 decibels per kilometer (1 percent of the light remains after traveling 1 kilometer). By 1972 the team creates glass with a loss of 4 decibels per kilometer. Also in 1970, Morton Panish and Izuo Hayashi of Bell Laboratories, along with a group at the Ioffe Physical Institute in Leningrad, demonstrate a semiconductor laser that operates continuously at room temperature. Both breakthroughs will pave the way toward commercialization of fiber optics.
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1973 |
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Chemical vapor deposition process
John MacChesney and Paul O’Connor at Bell Laboratories develop a modified chemical vapor deposition process that heats chemical vapors and oxygen to form ultratransparent glass that can be mass-produced into low-loss optical fiber. The process still remains the standard for fiber-optic cable manufacturing.
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1975 |
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First commercial semiconductor laser
Engineers at Laser Diode Labs develop the first commercial semiconductor laser to operate continuously at room temperatures. The continuous-wave operation allows the transmission of telephone conversations.
Standard Telephones and Cables in the United Kingdom installs the first fiber-optic link for interoffice communications after a lightning strike damages equipment and knocks out radio transmission used by the police department in Dorset.
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1977 |
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Telephone companies fiber optic trials
Telephone companies begin trials with fiber-optic links carrying live telephone traffic. GTE opens a line between Long Beach and Artesia, California, whose transmitter uses a light-emitting diode. Bell Labs establishes a similar link for the phone system of downtown Chicago, 1.5 miles of underground fiber that connects two switching stations.
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1980 |
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Fiber-optic cable links major cities
AT&T announces that it will install fiber-optic cable linking major cities between Boston and Washington, D.C. The cable is designed to carry three different wavelengths through graded-index fiber—technology that carries video signals later that year from the Olympic Games in Lake Placid, New York. Two years later MCI announces a similar project using single-mode fiber carrying 400 bits per second.
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1987 |
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"Doped" fiber amplifiers
David Payne at England’s University of Southampton introduces fiber amplifiers that are "doped" with the element erbium. These new optical amplifiers are able to boost light signals without first having to convert them into electrical signals and then back into light.
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1988 |
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First transatlantic fiber-optic cable
The first transatlantic fiber-optic cable is installed, using glass fibers so transparent that repeaters (to regenerate and recondition the signal) are needed only about 40 miles apart. The shark-proof TAT-8 is dedicated by science fiction writer Isaac Asimov, who praises "this maiden voyage across the sea on a beam of light." Linking North America and France, the 3,148-mile cable is capable of handling 40,000 telephone calls simultaneously using 1.3-micrometer wavelength lasers and single-mode fiber. The total cost of $361 million is less than $10,000 per circuit; the first transatlantic copper cable in 1956 costs $1 million per circuit to plan and install.
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1991 |
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Optical Amplifiers
Emmanuel Desurvire of Bell Laboratories, along with David Payne and P. J. Mears of the University of Southampton, demonstrate optical amplifiers that are built into the fiber-optic cable itself. The all-optic system can carry 100 times more information than cable with electronic amplifiers.
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1996 |
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All-optic fiber cable that uses optical amplifiers is laid across the Pacific Ocean
TPC-5, an all-optic fiber cable that is the first to use optical amplifiers, is laid in a loop across the Pacific Ocean. It is installed from San Luis Obispo, California, to Guam, Hawaii, and Miyazaki, Japan, and back to the Oregon coast and is capable of handling 320,000 simultaneous telephone calls.
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1997 |
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Fiber Optic Link Around the Globe
The Fiber Optic Link Around the Globe (FLAG) becomes the longest single-cable network in the world and provides infrastructure for the next generation of Internet applications. The 17,500-mile cable begins in England and runs through the Strait of Gibraltar to Palermo, Sicily, before crossing the Mediterranean to Egypt. It then goes overland to the FLAG operations center in Dubai, United Arab Emirates, before crossing the Indian Ocean, Bay of Bengal, and Andaman Sea; through Thailand; and across the South China Sea to Hong Kong and Japan.
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