MASSACHUSETTS - The telecommunications industry has invested billions of dollars to lay thousands of miles of optical fiber around the world, confident that users will need the advantages of increased bandwidth and speed that glass fibers offer over copper wires.
But a new generation of optical fibers being developed in labs in England and the United States promises to deliver dramatically increased performance. These new fibers could make today’s glass strands as obsolete as those strands have made copper.
Glass fiber carries data in the form of pulses of laser light. The light pulses on and off to represent digital data, and light at different frequencies can move several data streams over one strand of fiber. The light moves down the strand and is reflected back toward the core as it bounces off the edges of the fiber.
Today’s high-speed telecommunications networks can carry data 70 kilometers, or about 44 miles, before the signal needs to be amplified. Impurities in the glass strands and leaks as the signal bounces off the sides of the strand require periodic boosts in the signal.
According to Technology Review, a publication of the Massachusetts Institute of Technology, British and American researchers working separately have come up with a novel way to improve the performance of today’s fibers. Instead of making the strands solid like fine wires, they make them hollow like tiny pipes. The laser pulse moves down the empty core of the fiber, traveling through air rather than through glass.
One company, OmniGuide Communications, formed by several MIT researchers, believes the new technology could deliver optical networks so efficient that they would not require any amplifiers. Since amplifiers cost $1 million each and must be installed and maintained even when cables travel under the ocean, that would be a major benefit to network operators.
Because air does not degrade optical signals the way silicon does, data could be transmitted over multiple channels by using frequencies set closer together, packing more information into each strand. Today’s data rates of 25 trillion bits per second for each strand of fiber could be eclipsed by rates several times as high.
Moving the new technology from the lab to the marketplace is a challenge, the researchers admit. The U.S. researchers are saying little about their progress, but those in England report promising success in simply bundling some hollow glass rods, heating them and pulling them to many times their original length. To illustrate the size of the resulting fiber, a scientist explains that if the hole were the size of a railroad tunnel, the fiber would reach from the Earth to Jupiter.