Researchers build fiber cable capable of near light-in-vacuum throughput

(Phys.org) —A research team at the University of Southampton in England has built a fiber cable that is capable of carrying data at 99.7 percent of the vacuum-speed of light. They have done so, they report in their paper published in the journal Nature Photonics, by constructing a cable with a hollow core and special inner walls that prevent refraction.

Fiber cables technically at least, carry data at the speed of light (299,792,458 meters per second in a vacuum), because the media they carry, is in fact a beam of light. But, in practice, data is carried far slower than that because of latency delays caused by refraction as light moves through the silica glass, which reduces common fiber cable data rate throughput by approximately 31 percent. To get around this problem, researchers have been looking at ways to replace the core of the fibers with air, which suffers far less from refraction. The stumbling point has been how to get the light beams moving through the cables to follow the cable when bends and turns are encountered. That's where this new research comes in—the group has found a new way to build a hollow core fiber cable that allows for bending light as it moves around turns while minimizing loss due to refraction.

The secret is, the team reports, an "ultra-thin photonic-bandgap rim" that provides low data loss, a wide bandwidth and far less latency than standard fiber cables. The result is a cable that in the lab was able to move data, using division multiplexing, at a rate of 73.7 terabits per second, which is approximately 1000 times better than standard fiber cable.

There is a hitch, of course. While data loss is relatively low (3.5 dB/km), it's still too high for use with anything but very short-hop applications, such as the fiber connections inside of supercomputers or perhaps within a data center where the paths the fiber cables take can be run in extremely straight lines. Because of that, the researchers will be working to improve their cable—if they succeed it could one day mean the end of waiting when downloading files, or better yet, to making applications such as real-time ultra high definition 3D transmissions, possible for general use across the Internet.

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