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Light-Beam 'twins' Take Data Farther


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The individual fiber strands of a fiber-optic cable.

Pairing light beams can help send a message through fiber-optic cables four times farther than using a single beam, according to Bell Laboratories researchers.

Credit: Guardian UK

Bell Laboratories researchers have developed a method involving paired light beams that can increase the data-carrying properties of fiber-optic cables. The researchers say that paired beams can travel four times farther than a single beam, and they used the technique to send a signal of 400GB/s down 12,800 km of optical fiber, farther than the longest trans-oceanic fiber link.

What limits the distance a given light signal can travel is how much power there is in the beam. However, increased power leads to more light interacting with the material of the fiber, which adds "noise" to the beam and limits the fidelity with which data can be transmitted.

The researchers created a pair of phase-conjugate beams, each carrying the same data. The noise that each gathers is a mirror image of that on the other, according to Bell Laboratories researcher Xiang Liu. "At the receiver, if you superimpose the two waves, then all the distortions will magically cancel each other out, so you obtain the original signal back," Liu says. "This concept, looking back, is quite easy to understand, but surprisingly, nobody did this before."

From BBC News
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