When I first came to the USA in the late 1960s, making a transatlantic phone call to my family in England was fraught with difficulty. Calls had to be "booked" through an operator and, if and when a connection was established, I had to shout to be heard above the static noise level. Today, I can direct-dial my brother in London and be connected in a fraction of a second with a crystal-clear line on which we can literally hear a pin drop. That`s all due to the magic of fiberoptic cable that has turned the world into a global village not just for voice transmissions but also for data and video.
In his latest book, City of Light (Oxford University Press, New York, 1999), science writer Jeff Hecht expertly tells the story of the painstaking discovery, rapid development, and remarkable applications of optical fibers. Hecht, a veteran contributing editor to Laser Focus World, has covered fiberoptic technology for more than 20 years. His book, the latest addition to Oxford`s splendid Sloan Technology Series, traces the story of fiberoptics from a Victorian parlor trick to the foundation of today`s global communications network. I strongly recommend City of Light for your own bookshelf and for anyone with an interest in communications.
Fountains of light
Hecht`s fascinating history literally begins in the dark with the tale of a Swiss engineer by the name of Daniel Colladon who, in 1841, first demonstrated light guiding with a jet of water. Colladon`s experiments were followed by a series of giant illuminated fountains at the International Health Exhibition in London in 1884. Glass fibers existed at the time and may have dated back to the Egyptians in 1600 BC, says Hecht. However, it wasn`t until 1965 that Charles Kao and George Hockham, two research scientists working at Britain`s Standard Telecommunications Laboratories, were able to make a clad optical fiber and demonstrate potentially practical communications through the fiber.
Kao, who was too impatient to wait for the formal publication of his and Hockham`s work, gave a talk on January 27, 1966, at the London headquarters of the Institution of Electrical Engineers. The talk made little impression on the world outside. Hecht reports that a British engineering magazine devoted a small part of one page to Kao`s talk. "A small American newsletter named Laser Focus also took note," says Hecht. I could not even begin to estimate the many hundreds of pages that Laser Focus World has devoted to fiberoptics since Kao`s momentous 1966 talk. However another six years were to pass before Donald Keck and his colleagues at the Corning Glass Works` Sullivan Research Center in western New York State developed the low-loss fiber that was to make fiberoptic communications economically feasible.
As Hecht makes very clear in his book, suitable light sources and detectors are necessary for an optical fiber communications link. By a remarkable coincidence, the early 1970s also saw some significant breakthroughs in semiconductor laser technology. Scientists at Russia`s Ioffe Physico-Technical Institute in Leningrad and at Bell Laboratories in New Jersey were engaged in a race to develop a CW heterojunction laser. Bell Labs claimed victory, although later evidence suggests that the Russians beat the Americans to the punch. Interestingly, notes Hecht, Rudy Kompfner, than head of transmission research at Bell Labs, told Laser Focus that he did not "expect the new diode lasers to be used in practical communications for many years, probably well into the 1980s." In fact, the first commercial fibers were installed in 1977!
Today, fiberoptic networks are ubiquitous for both long- and short-haul transmissions, and the capacity of fiber is expanding by leaps and bounds making communications faster and cheaper than ever before. The only barrier to be surmounted is the "last mile" from the street to the office desk or the home telephone. The world is wired by skinny glass fibers into a true "City of Light." The key to the last mile is most likely to be passive optical networks, says Hecht, which contain few transmitters and are cheap to manufacture and install. Optical switches are going to bring further benefits, predicts Hecht, as integration continues with the rapid development of optical integrated circuits. And you can be sure that Laser Focus World will continue to "take note of" fiberoptics.