UC San Diego Researchers Amp Up Internet Speeds

COBOL Leads Us Back To The Future

Photonics researchers at the University of California, San Diego have increased the maximum power, and therefore the distance, at which optical signals can be sent through optical fibers, indicating a new path towards ultra high-speed Internet connectivity.

The team of electrical engineers broke through key barriers that limit the distance information can travel in fiber optic cables and still be accurately deciphered by a receiver -- information traveled nearly 7,5000 miles through fiber optic cables with standard amplifiers and no electronic regenerators.

The test results suggest the potential for elimination of electronic regenerators placed intermittently along the fiber link.

The business potential for a breakthrough of this scale is fairly obvious -- faster networks mean more people and more capacity to send larger and larger sums of data across the Internet -- however, it's not clear when something of this could move from the lab to the enterprise.

The laboratory experiments involved setups with both three and five optical channels, which interact with each other within the silica fiber optic cables, but the researchers noted this approach could be used in systems with far more communications channels.

The results of the experiment, performed at UC San Diego's Qualcomm Institute by researchers from the Photonics Systems Group and published in the June edition of the research journal Science, indicate that fiber information capacity can be notably increased over previous estimates by pre-empting the distortion effects that will happen in the optical fiber.

The official name of the paper is "Overcoming Kerr-induced capacity limit in optical fiber transmission."

"Today's fiber optic systems are a little like quicksand," Nikola Alic, a research scientist from the Qualcomm Institute, the corresponding author on the Science paper, and a principal of the experimental effort, wrote in a June 25 statement.

"With quicksand, the more you struggle, the faster you sink," Alic added. "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, which in turn extends how far signals can travel in optical fiber without needing a repeater."

Eduardo Temprana, left, and Nikola Alic at work in the Photonic Systems lab.

The same research group published a paper last year outlining the fact that the experimental results they are now publishing were theoretically possible, and the university has also filed a patent on the method and applications of frequency-referenced carriers for compensation of nonlinear impairments in transmission.

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"Crosstalk between communication channels within a fiber optic cable obeys fixed physical laws. It's not random," Stojan Radic, a professor in the Department of Electrical and Computer Engineering at UC San Diego and the senior author on the Science paper, said in a statement.

"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," Radic added. "Our approach conditions the information before it is even sent, so the receiver is free of crosstalk caused by the Kerr effect."

The Kerr effect, also called the quadratic electro-optic effect (QEO effect), is a change in the refractive index of a material in response to an applied electric field -- a challenge which the team at UC San Diego appears to have surmounted.