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Trapping the Light Fantastic
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14916 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
10 / 1988 |
2,948 Words |
| Author
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Diane Johnson
Daine Johnson is a free-lance science writer residing in
Boulder, Colarado |
Optoelectronics is a catchall term that refers to a whole spectrum of ingenious ways of integrating the dazzling speed of light with the proven reliability of electronic components. In essence, optoelectronics, sometimes called photonic technology, is based on substituting the quantum unit of light energy, photons, for electrons as information carriers. On the horizon are super high-speed computers, light-based systems designed to handle special industrial tasks, and fantastic developments on the boundaries of artificial intelligence, like a photonic dream machine.
What's Already In Place And What Waits In The Wings
Some of the building blocks of photonic technology already exist. Optical fibers, optical storage discs, special high-powered lasers, and holographic systems are readily available commercially. But their full potential for advancing optoelectronics has yet to be realized.
Take fiber optics, for example. Hair-thin optical fibers, carrying messages encoded in light, are good over the short and the long haul. They are currently whisking telephone messages around the world and linking high-speed computers into special-use networks.
For residential end-users in the United States, however, fiber optics now carry their phone signals only to a central switching station that is, on the average, 18,000 feet away from their homes. Then the optical message is converted to an electronic message that is carried to the house on small twisted pairs of copper wires. To bring optical messages all the way to the residential user would require the tremendous expense of replacing the branching electronic network of wires and switches.
Despite the small diameter of optical fibers, they can carry far more information than larger copper wires, and at a much higher speed. The well-known speed of light, 186,000 miles per second, applies to photons traversing empty space, whereas light passing through a glass fiber is slowed to about two-thirds that speed. In theory, electrons can move at the speed of light, too. But in practice, the resistance in metal wires slows electrons down to approximately a tenth of that speed.
Just one of today's fine glass optical fibers can carry as many telephone conversations as 625 bulky copper wires--and with greater clarity. Transmitting an optical signal generally takes less energy, too. Not only are
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