Nov. 19, 1998 MURRAY HILL, N.J. - Scientists and engineers from Bell Labs, the research and development arm of Lucent Technologies, have demonstrated an innovative "no-fiber optical data link" and set a world record -- transmitting 2.5 gigabits (billion bits) of information per second, error free, through 2.4 kilometers (1.5 miles) of free space (air).
Commercial wireless data links, using multiple transmitters, operate at up to only 622 megabits (million bits) per second.
Worldwide demand for communications services is growing rapidly, and a network of multi-gigabit free-space data links could provide a high-capacity alternative to microwave links, optical fiber, or cable systems in places where those technologies are impractical or prohibitively expensive.
The experimental Lucent technology was developed in Bell Labs Government Solutions business. It integrates two custom-built telescopes, manufactured by AstroTerra Corp. in collaboration with Lucent, with standard optical transmitters and receivers and a high-power optical amplifier. Data is sent, through the air, from the transmitting telescope to the receiving telescope and focused onto the core of an optical fiber using coupling optics within the second telescope.
The Lucent team worked with colleagues at AstroTerra to test the system prototype at AstroTerra's facility in San Diego, Calif., and the group presented its results in a technical paper last week at the Photonics East conference in Boston. Co-authors of the paper are Paul Szajowski, Gerald Nykolak, James Auborn, Herman Presby and G.E. Tourgee, of Bell Labs, and E. Korevaar, J. Schuster, and I.I. Kim, of AstroTerra.
"This test stands as a remarkable achievement in wireless data communication," said AstroTerra President Eric Korevaar. "It's a watershed event in free-space optical technology."
The test combined innovative high-speed optoelectronic equipment developed by Lucent Technologies with AstroTerra's multiple-transmitter laser communication technology.
"There are numerous applications for connecting multi-gigabit data and communications networks where fiber-optic cables are not available or practical," said Mike Geller, Chief Technical Officer of Lucent's Government Solutions business. "This technology is compatible with our optical and data networking equipment, so we can hook up asynchronous-transfer-mode equipment, Internet packet switching systems and routers and other kinds of equipment at each end.
"It isn't intended to replace fiber, but rather to complement it," he said. "It fits niche applications. Because it requires a clear line of sight there are some places it can't go that fiber can, and adverse weather conditions, like heavy fog and snow, can present problems."
Potential applications for high-bandwidth optical wireless links include campus environments, multiple-building occupancy in metropolitan areas, and temporary data links where environment and cost make fiber connections impractical.
"Without alternate network system technologies and delivery topologies, overall effective network speed will be reduced and frequent bottlenecks within networks will become more commonplace in the very near future," predicted Szajowski.
Future plans for the Lucent team call for the development of 10-gigabit data rates, transmission across greater link distances, and the integration of wavelength division multiplexing (WDM) technology, a method for increasing capacity by transmitting information over multiple wavelengths, or colors, of light.
Lucent Technologies designs, builds and delivers a wide range of public and private networks, communications systems and software, consumer and business telephone systems and microelectronics components. Bell Labs is the research and development arm for the company. Further information about the company is available at http://www.lucent.com.
AstroTerra Corp. manufactures a full line of optical wireless data communications equipment, from the economical TerraLink 1000 to the high-speed TerraLink 8-622. More information on AstroTerra is available at http://www.astroterra.com.
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