Researchers break key communications barrier; pave way for faster Internet

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Optical fibers provide communication speeds that no other medium provide, but they suffer from a roadblock as well that limit the distance for which information can travel without getting distorted. Photonics researchers at the University of California, San Diego have increased the maximum power — and therefore distance — at which optical signals can be sent through optical fibers.

This technological breakthrough holds the key to increasing data transmission speeds over fiber optic cables that serve as the backbone of almost all communications network globally including the Internet, cable, wireless and landline networks.

Researchers at the university were able to successfully decipher information after it travelled a record-breaking 12,000 kilometers through fiber optic cables with standard amplifiers and no repeaters. The findings implicate the elimination of electronic regenerators from being placed periodically along the fiber link.

These regenerators are effectively supercomputers and must be applied to each channel in the transmission. The electronic regeneration in modern lightwave transmission that carries between 80 to 200 channels also dictates the cost and, more importantly, prevents the construction of a transparent optical network. As a result, eliminating periodic electronic regeneration will drastically change the economy of the network infrastructure, ultimately leading to cheaper and more efficient transmission of information.

The breakthrough in this study relies on wideband “frequency combs” that the researchers developed. The frequency comb described in this paper ensures that the signal distortions — called the “crosstalk” — that arises between bundled streams of information travelling long distances through the optical fiber are predictable, and therefore, reversible at the receiving end of the fiber.

“Crosstalk between communication channels within a fiber optic cable obeys fixed physical laws. It’s not random. We now have a better understanding of the physics of the crosstalk. In this study, we present a method for leveraging the crosstalk to remove the power barrier for optical fiber,” explained Stojan Radic, a professor in the Department of Electrical and Computer Engineering at UC San Diego and the senior author on the Science paper. “Our approach conditions the information before it is even sent, so the receiver is free of crosstalk caused by the Kerr effect.”

The research is published in journal Science.