Hollow core fibre could shine a light on faster broadband

The University of Bath is experimenting with a new type of material that could increase data transfer speeds and reduce part of the cost of installing broadband networks.

The University of Bath is experimenting with a new type of material that could increase data transfer speeds and reduce part of the cost of installing broadband networks.

Internet service providers (ISPs) say the cost of installing a super-fast broadband network throughout the UK is expensive because of the cost of laying the fibre cable connections, which are necessary to deliver higher speeds.

Businesses based in areas where demand for high speed broadband might not justify an operator investing in installing fibre could be left with second rate connections, according to analysts.

But a new approach to manufacturing "hollow core fibre" - a type of fibre which uses air rather than conventional glass fibre to transmit data as light - could make installations cheaper in the future. To understand why hollow core fibre is better than conventional fibre, a science lesson is needed.

Conventional fibre optic connections carry data using light through shafts of cylindrical glass, which look a bit like plastic straws.

But because the light has to travel through glass, the speed of data transfers can be slowed. For example, the glass can be damaged if there is too much light. Glass also causes light to spread out in a blurring effect, which could disrupt or slow the flow of data.

In hollow core designed fibre, light travels down a hollow core and is guided by tiny air holes rather than glass, overcoming the limitations. These fibres - which can be a kilometre in length and the width of a human hair - can trap light so that it does not become absorbed by matter or lose its power. It does this by the structure of the tiny round holes running the length of the photonic crystal fibre, arranged in a honeycomb shape.

Jonathan Knight, a professor at the University of Bath, said that the problem in developing hollow-core fibres is that only a special sort of optical fibre can guide light down an air hole. Knight said that the detailed nature of these fibres means that they have been difficult to produce and they can only work for a limited range.

The new procedure developed by the Bath photonics group, shows how a tiny change to these fibres - narrowing the wall of glass around the large central hole by just a hundred nanometres (a 10-millionth of a metre) broadens the range of wavelengths that can be transmitted.

The procedure omits some of the most difficult steps in the fabrication procedure, reducing the time required to make the fibres from around a week to a single day.

The superior performance of the fibre means that it could have a significant impact in a range of fields such as laser design and pulsed beam delivery, spectroscopy, biomedical and surgical optics, laser machining, the automotive industry and space science, said Knight

"The consequences of being able to use light rather than electrical circuits to carry information will be fundamental," said Knight. "It will make optical fibres many times more powerful and brings the day when information technology will consist of optical devices rather than less efficient electronic circuits much closer."

For biomedical research, the fibres could be used to deliver light for diagnosis or surgery anywhere - even deep inside the body.

"The most immediate use of these types of fibre will be in manufacturing, though," said Tim Birks, a professor in the project team.

A manufactuer of laser equipment is trialling the fibre for fine laser cutting in its manufacturing process.

"The fibre is of particular use in delivering highly focused and concentrated pulses of light - so any application in biomedical or manufacturing operations will be relevent. Birks said that the application for broadband was still some way off, but that the first steps had been paved for greater innovation.

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