Hollow-Core Fibre breakthrough could herald more cost effective data centres and 5G networks

The University of Southampton’s world-leading Optoelectronic Research Centre (ORC) is to announce a significant breakthrough in Hollow-Core Fibre (HCF) technology at ECOC2018 in Rome, Italy, this week.

Hollow-core fibres are optical fibres where the conventional glass in the core is replaced by a gas or vacuum. These fibres, with a ’holey’ centre, have attracted scientists worldwide for over a century owing to their faster light speed giving less information delay – an important attribute for data centres, 5G mobile communications and driverless vehicles. Remarkably, these fibres also have the potential for lower loss and higher data transmission capacity than the conventional all-solid glass optical fibres in use today.

Despite predictions, the use of HCFs in optical communications has to date been severely limited by their relatively-high optical loss. The breakthrough to be reported this week, combined with the ultimate potential of this new technology, could herald the creation of larger and more distributed data centres, and more resilient and cost effective 5G networks.

The post-deadline paper, ‘Record Low-Loss 1.3dB/km Data Transmitting Antiresonant Hollow Core Fibre’ is a joint initiative between the ORC, through the ERC ‘LightPipe’ project, and Lumenisity Ltd. It reports the world’s lowest optical signal attenuation in a data-transmitting HCF.

The result is particularly significant, as it breaks the previously recorded HCF attenuation level of 1.7dB/km, reported as long ago as 2004.*

The results have been enabled by a novel fibre structure invented at the ORC**, that modelling predicts offers future losses as low as, or better than, standard silica fibres. The Nested Antiresonant Nodeless hollow-core Fibre (NANF) developed by the Southampton team incorporates an ingenious arrangement of twelve carefully-positioned glass capillaries with a wall thickness of just one thousandth of a millimetre. These tubes surround an empty central region and create a hollow pipe in which the light is guided.

Professor Francesco Poletti of the Optoelectronics Research Centre, who leads the team and the LightPipe programme, said: “This result represents a key first milestone in the practical development of a new hollow core fibre technology that is considerably easier to manufacture than previous generations. NANF technology could enable breakthroughs in many areas of science and technology, from sensing to laser power delivery and data communications. A few months ago it was just a promising idea on a piece of paper, but with the help of the exceptional members of our team we already have this first experimental demonstration.â€?

“Furthermore, the experiments agree well with numerical simulations, giving us confidence in predictions that the capacity of the fibre could be increased by a further factor of two and the loss decreased by a factor of ten through design and fabrication improvements.â€? Applications of this new technology will be explored in partnership with a range of academic and industrial project collaborators through the EPSRC-funded Airguide Photonics programme.

* B.J. Mangan, et al., Proc. OFC 2004, PD24 ** F Poletti, Opt. Express 22, 23807-23828 (2014)