Lucent Scientists See Limits of Fiber Communications

MURRAY HILL, N.J., July 2 -- Scientists from Lucent Technologies' Bell Labs have calculated the maximum amount of information that can be transmitted over optical fiber. The team, whose results appear in the British journal Nature, determined that it is theoretically possible to send approximately 100 terabits of information, or roughly 20 billion one-page e-mails, simultaneously per strand of fiber. "As networks continue to make communication faster, smaller, cheaper and smarter in the next decade, there will be an even greater emphasis on fiber optics technology," said Rod Alferness, senior vice president of optical networking research at Bell Labs. "As we light more optical fiber, and couple this with all-optical switches like the Lucent WaveStar LambdaRouter, we will continue to improve the speed and quality of metropolitan and backbone networks, helping to enrich the end-user experience."
The scientists employed an analogy from quantum physics, together with ideas from information theory. They looked at telecommunication systems that use wavelength division multiplexing, and estimated how much information can be conveyed from a transmitter to a receiver. They found that if a signal were sent with too little power, the signal would be overcome by the noise in the system. On the other hand, sending a signal that is too powerful will interfere with other signals. With wavelengths and values typically used in communication networks, the scientists determined that it is theoretically possible to send 100 terabits of data per second without excessive noise or interference.