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Summary:

A new technique packs more data into fiber optic cables by beaming data in tightly wound loops.

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The internet reaches you via thousands of miles of laser-filled glass, copper or plastic wires, into which companies try to pack as much data as possible. They’ve tried more lasers, multiple light-guiding cores and better chips, all in the name of streaming “Hey Arnold!” on Netflix a little bit faster.

In an effort to stuff even more data into fiber-optic cables, researchers have developed data beams that travel in a spiral instead of a straight line without getting jumbled together. The result is more data in the same length of cable. Researchers at Boston University and the University of Southern California were able to send 1.6 terabits per second across a distance of 1 kilometer. The new technique was published in the June 28 edition of Science (subscription required).

The spiral beams can be combined with existing bandwidth boosting techniques, such as sending many beams through a cable at once. The spiral beams are sent along different paths and made to be different colors, which differentiates them and lowers the computing necessary to process them once they reach their destination.

Scientists have studied spiral beams widely in the past and thought them to be too unstable for a fiber optic cable. They would jumble together, rendering them unreadable. The next challenge will be improving the distance and speed at which the beams can travel, not to mention installing fiber networks capable of carrying them.

  1. Data rate is dependent on the duration of light pulses – shorter light pulses mean more data. But shorter light pulses also makes it more susceptible to jitter which would mangle up the pulses so that they cannot be distinguished from each other. Jitter is caused by different path length within the fiber while the light is reflected on the outside of the core in a zick-zack pattern, each impulse a bit different.

    The current method of counteracting that is by making the core of the fiber smaller and the total light path shorter that way. The current practical limit is 40 Gbps, for most connections not using more than 10 Gbps. 100 Gbps Ethernet for instance uses 10 pairs of fiber, or 4 different colors on one single mode fiber pair.

    The goal of the circular pattern is most likely to reduce path length differences.

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