General

Ah! The Power of Fiber

In the 1960's film The Graduate a youthful Dustin Hoffman was given a single word of advise concerning his future … that word was "plastics." If the film were made today, instead of plastics, that word might be "fiber."

by Jim Thompson [July 20, 2001]

New research indicates that a single strand of optical fiber can transmit 10 times more information than was previously thought. The implication is that fiber offers a stable, long-term, scalable solution for networks of the future.

A team of researchers from Bell Labs, a division of Lucent Technologies, has found that it's possible to send approximately 100-terabits of information—or roughly one billion simultaneous telephone calls per second—over a single strand of fiber. The discovery opens new doors to the future of communications and may re-write the way traffic is carried over the Internet.

"Besides the obvious advantages that fiber offers a super fast and efficient pathway, the discovery also shows that fiber is a very good long-term choice for scalable networks," said Saswato Das, spokesman for Bell Labs. "Coupled with all optical switches, like the Lucent WaveStar LambdaRouter, the new capabilities will also help improve the speed and quality of metropolitan and backbone networks."

In laboratory experiments, Bell Labs demonstrated the ability to transmit 10-terabits of information per second compared to just under two terabits currently seen in commercial optical systems.

Sense and sensibilities
According to Das, the Bell Labs scientists used theory, quantum physics and a healthy dose of common sense to measure the limits of the fiber cables.

"This is a conservative, theoretical limit. It is difficult to calculate how much information can be transmitted over a glass fiber because the physical properties of glass make light transmitted over fiber susceptible to scrambling in a very complicated fashion," noted Das.

He explained that light traveling tough a glass fiber is susceptible to non-linear effects. The speed of a light signal traveling through fiber is not a constant as it would be in free space, but is dependent on the intensity of the light. Such non-linear effects cause a portion of the signal traveling through the fiber strand to be turned into noise.

Das added that the scientists working on the project, did take the problems associated with interference and noise into account during their tests and when making their final conclusions.

Although it will be some time before the theoretical limits of fiber will be reached in the real world, it's clear that fiber does offer a long-term solution to the ever increasing demands of the Internet and worldwide communications.

Narrow-minded
Unfortunately, the fiber optic's superior capacity doesn't necessarily mean that Internet traffic moves faster over glass. We are already experiencing, what some call, an electronic bottleneck. Unless fundamental changes are made in the type of routers and switches that are used, this narrow is likely to form an impasse—getting worse before it gets better.

While fiber will help ease the problem, it doesn't offer the final solution. Network capacity and bandwidth are like closet space—you never have enough. As more people begin to use the Internet and exploit its potential through video-on-demand and streaming audio and video, and always-on high-speed access, the demand for capacity increases which affects the overall efficiency of the backbone. Already metropolitan networks in many areas are saturated—while transport demand increases.

According to Das, "typically, light signals travel across the backbone as light. They are converted to electronics, then transmitted again as either electronic signals or as light. This slows things down at all the hubs."

In Das' view, "the only way to keep up with the demand is to replace electronic routers and switches with optical equipment. The use of all optical switches is the only way to increase the speed of the network and handle larger applications."

For ISPs who are looking toward the future, "fiber" may be only word they need to know.

—End