DARPA Develops Optical Fibre That’s 30 Percent Faster

The Defence Advanced Research Projects Agency (DARPA) has managed to create hollow optical fibre that improves data transmission over conventional broadband fibre by 30 percent.

This is not the first time such material has been made, but it’s the first photonic crystal fibre manufactured in the US, and its characteristics are well ahead of the competition.

With hollow fibre, the unusual “spider-web-like” design and photonic crystal coating forces light to travel through channels of air, instead of the glass around it, which allows the beam carrying information to achieve speeds just 0.3 percent slower than the speed of light.

As with most DARPA projects, the technology was developed primarily for military uses. However, that doesn’t mean that we will not see commercial applications of hollow fibre in the next few years.

Earlier this year, researchers at the Optoelectronics Research Centre of the University of Southampton had given the first UK demonstration of hollow fibre in action.

Better fibre

DARPA is the US agency that has given birth to many advanced tech projects including flying cars, robots, laser weapons and ARPANET, the earliest predecessor of the Internet.

In conventional fibre optic broadband cables, light is transmitted through glass or plastic, while hollow fibre pushes light in the gaps between glass layers, where it is perfectly reflected by photonic crystal coating.

The concept has been around for years, and several companies are currently selling hollow fibre. What makes the material developed by Honeywell International on behalf of DARPA stand out is its specific properties.

DARPA’s hollow fibre works in a single-spatial-mode, which forces light into a single path for higher bandwidth over longer distances. It offers low loss of light and polarisation control – which means the beam maintains the original direction of the light waves. The agency says this makes it perfect for military uses.

This particular material was developed to be used in the Compact Ultra-Stable Gyro for Absolute Reference (COUGAR) program, which aims to allow precise computer-assisted navigation in areas where signals from GPS satellites are jammed or unavailable.

“Previous instantiations of hollow-core fibre have shown these high propagation speeds, but they weren’t able to do so in combination with the properties that make it useful for military applications,” said Josh Conway, program manager at DARPA. “The real breakthrough with COUGAR fibre is that it can achieve a single-spatial-mode, maintain polarisation and provide low loss, all while keeping more than 99 percent of the optical beam in the air.”

It seems that in a typical DARPA fashion, the organisation has come up with technology that could have countless uses outside of the defence industry.

“While we are still working on integrating this new technology into a gyroscope, the fibre itself is revolutionary,” added Conway. “This type of technology may also lend itself to other types of high-power sensors and additional applications where intense optical beams are required. Hollow-core fibre is also naturally radiation hardened, so it may open up fibre applications to space systems.”

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