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PTB Industry News				March 1, 1999

Bell Labs Builds Multi-Channel
Optical Wireless System

Four Colors of Light Carry 10 Billion Bits of Data Per Second

MURRAY HILL, NJ, Feb. 25 -- A team of scientists and engineers from Bell Labs, the R&D division of Lucent Technologies, has demonstrated a prototype multi-channel optical wireless transmission system. The experimental system was built for Lucent's Government Solutions business. Bell Labs researchers says that the system uses four wavelengths, or colors, of light to transmit 10 gigabits of information through 2.7 miles of free space per second; each wavelength carries 2.5 gigabits of data per second. Today's highest-capacity commercial wireless data links operate at less than 1 gigabit per second. The dense wavelength division multiplexing (DWDM) optical wireless transmission experiment was conducted in northern New Jersey, with two optical terminals 4.4 km apart. According to Bell Labs, it successfully demonstrated a 10 Gb/s-capacity, free-space terrestrial link transmitting error-free over a horizontal path. The link's 1550 nm fiber components included a multimode DWDM and high-power Er/Yb optical amplifiers. The new technology integrates custom-built telescopes, standard optical transmitters and receivers, and a high-power optical amplifier. Light signals are sent from a transmitting telescope to a receiving telescope and focused onto the core of an optical fiber using coupling optics within the second telescope. "This high-capacity, free-space optical link is made possible by recent developments in both telescope design and fiber devices," said Gerald Nykolak, a Bell Labs researcher who described the system last week at the Optical Fiber Communication (OFC) Conference in San Diego. The system's developers say that the new technology offers potential to provide rapidly deployable high-bandwidth connections to optical networks in situations where a fiber connection is impractical. According to Mike Geller, chief technical officer of Lucent's Government Solutions business, it might be used to make connections across a body of water. Other applications might include temporary installations for one-time events such as the Olympic Games, battlefield communications, and restoring service after a cable break. "Integrating optical wireless as an adjunct to fiber-optic systems would require no governmental licensing or frequency allocation," said Geller. "It would be effective, particularly where fiber is unavailable or its installation would be prohibitively expensive." Geller added that because the new system requires a clear line of sight, there are some places that it cannot go that are reachable via fiber systems. Adverse weather conditions, such as heavy fog and snow, might also affect the new technology. Nykolak co-wrote the OFC technical paper with Bell Labs colleagues Paul Szajowski, Jim Jacques, Herman Presby, Joe Abate, Jerry Tourgee, and Jim Auborn, all of Lucent's Government Solutions group. PTB Home