PRACTICAL SYSTEMS TAKE SHAPE

It proved possible to get around these demands, at least to some degree, by sidestepping the use of lasers. A simpler type of device was the light-emitting diode, or LED, which resembles the red and green indicator lights in a cassette player or VCR. LEDs proved adequate for transmitting limited numbers of telephone calls over modest distances, but they lacked the efficiency and capacity needed for long-distance and transoceanic service.

Again, it was necessary to draw on work from the research laboratory. At about the same time that Panish and Hayashi were doing their breakthrough work on multilayered crystals, two colleagues at Bell Laboratories, J. R. Arthur and A. Y. Cho, were coming up with a different crystal-growth method--called molecular-beam epitaxy, or MBE. "Epitaxy" is the growth of crystals of one mineral on the face of crystals of another mineral, and MBE was so precise that it could put down a layer of semiconductor material with a thickness measured in atoms. By confining electrons and their emitted light, this extremely thin layer proved highly efficient at generating laser action while using less electric current. Even better, the new MBE devices achieved the desired 1,000,000-hour lifetimes.

Drawing on the basic understanding of crystal growth developed a decade or so earlier by scientists at Bristol University and Bell Laboratories, research into different methods of production and different semiconductor compounds continued through the 1970s and into the 1980s. By 1975, laser technology was sufficiently well developed to permit operational trials in major cities. From origins in the theoretical quantum physics of Albert Einstein, fiber-optic communication was now focused on the practical concerns of production, installation, and repair. Engineers were particularly concerned about repair--splicing broken optical fibers would be a challenge akin to cutting a hair from your head and then putting it back into place.

The first test came at AT&T in Atlanta in 1976. Work crews installed two fiber-optic cables--each 2,100 feet long and containing 144 fibers--by pulling them through standard underground ducts, which required the cables to negotiate sharp bends. To everyone's immense relief, installation did not break any of the fibers, nor did the tight bends degrade their performance. Commercial service began the next year in Chicago, where a fiber-optic system carried voice, data, and video signals over 1.5 miles of underground cable that connected two switching offices of the Illinois Bell Telephone Company.