Credit: Groman123 (CC BY-SA 2.0)
UK photonics researchers have developed a new kind of hollow-core optical fibre that can transmit light signals about 45% further than current telecom fibres before needing a boost.
The scientists from Microsoft Azure Fiber and the University of Southampton have called this a “breakthrough result” which paves the way for a potential revolution in optical communications.
With further advancements, the new fibre could enable more energy-efficient optical networks with unprecedented data transmission capacities.
“We have reported what we believe to be one of the most noteworthy improvements in waveguided optical technology for the past 40 years,” the researchers write in a study presenting the findings in Nature Photonics.
The development of low-loss optical fibres in the 1970s ushered in a new era of digital communications, enabling global telecommunications networks and the advent of the internet.
Since then, the field has pursued advancements to allow optical fibres to transmit more information over greater bandwidths, while simultaneously lowering attenuation to increase the distance a signal can travel before it requires boosting.
But the ‘minimum attenuation’ of silica glass fibres – the loss of optical power in a cable over 1km – has remained basically unchanged from 0.154 dB/km in 1985, to 0.1396 dB/km in 2024.
This means that about half of the light transmitted through an optical fibre is lost after about 20km, requiring regularly placed optical amplifiers to boost signals for longer distances.
The new optical waveguide surpasses conventional optical fibres in both loss and bandwidth.
Rather than a traditional solid silica glass core, the new design incorporates “a core of air surrounded by a meticulously engineered glass microstructure to guide light”.
The light is transmitted in the air-filled region to avoid the scattering and absorption which causes loss of signal power in solid glass fibres.
Scanning electron micrograph the fabricated fibre’s central air core, composed of 5 sets of double nested silica tubes stacked and fused within a jacket tube. Credit: Petrovich et al 2025, Nature Photonics (CC BY 4.0).
“This approach not only reduces attenuation and other signal degradation phenomena, but it also increases transmission speeds by 45%,” the authors write.
In laboratory experiments, the team showed that 1,550nm light – a wavelength commonly used in optical communications – attenuates by 0.091 dB/km in the new fibre.
This attenuation rises to just 0.1d B/km for a transmission window of 1,481nm to 1,625nm (18 THz).
“Neglecting absorptions from gases in the core and not of fundamental origin, the fibre guides light with <0.2 dB/km from 1,250nm to 1,730nm (66 THz), a 260% improvement over current telecoms fibres (25 THz),” the authors add.
Simulations also suggest that a stiffer fibre, with a thicker outer coating layer and larger air core, may achieve signal losses even lower than those reported in the study.
According to the authors, this would potentially herald in “a new era in long-distance communications as well as remote delivery of laser beams”.
More research is needed to confirm this, however.
“We are confident that, with advancements in produced volumes, geometrical consistency and reduced presence of absorbing gases in the core, double nested antiresonant nodeless hollow core fibres will establish themselves as a pivotal waveguiding technology,” the authors conclude.
“This innovation has the potential to enable the next technological leap in data communications.”