Researchers shatter fiber optic limits

Chuck Bednar for – @BednarChuck

The barriers limiting the distance that information can be transmitted over a fiber optic network have been completely shattered by photonics researchers at the University of California-San Diego, who have increased the power of optical signals nearly twentyfold.

The researchers report in the June 26 edition of the journal Science that they successfully deciphered information that had traveled a record-setting 12,000 kilometers through fiber optic cables with standard amplifiers and no repeaters (electronic regenerators used to artificially boost the signal).

According to Engadget, the engineers used wideband “frequency combs” in order to keep signal distortions (also known as “crosstalk”) that occur in the bundled streams of data traveling along the optical fibers predictable and can be reversed at the receiving end. Their work could result in faster Internet, cable, and wireless network speeds.

Like fine-tuning instruments before a concert

“Today’s fiber optic systems are a little like quicksand,” said Nikola Alic, a research scientist from the Qualcomm Institute and corresponding author on the study. “With quicksand, the more you struggle, the faster you sink. With fiber optics, after a certain point, the more power you add to the signal, the more distortion you get, in effect preventing a longer reach.”

“Our approach removes this power limit,” he added, “which in turn extends how far signals can travel in optical fiber without needing a repeater.” This breakthrough could eliminate the need to use electronic regenerators placed along the fiber link, leading to the development of less expensive and more efficient information transmission networks.

The UCSD team compared their approach to the way in which a concertmaster tunes orchestral instruments to play at the same pitch prior to the start of a concert. Typically, information transmitted through an optical fiber is done so through multiple communication channels, each of which operate at a different frequency. Using the frequency comb, the researchers synchronized the frequency variation of the different streams to make the process more harmonious.

“After increasing the power of the optical signals we sent by 20 fold, we could still restore the original information when we used frequency combs at the outset,” said UC San Diego electrical engineering Ph.D. student Eduardo Temprana, the first author on the paper. The frequency combs make sure that random distortions accumulated and made it impossible to reassemble the original information at the receiving end, he added.


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