Novel hollow-core optical fiber transmits data 45% faster with record low loss

Krystal Kasal
contributing writer

Gaby Clark
scientific editor

Robert Egan
associate editor

Despite the modern world relying heavily on digital optical communication, there has not been a significant improvement in the minimum attenuation—a measure of the loss of optical power per kilometer traveled—of optical fibers in around 40 years. Decreasing this loss would mean that the signal could travel further without being amplified, leading to more data being transmitted over longer distances, faster internet and more efficient networks.
Current fibers transmit light through silica cores, which have limited room for loss improvement. Another option is the hollow-core fiber (HCF), which theoretically allows for faster speeds due to the ability of light to travel faster through air than through silica. Still, scientists struggled to design HCFs that actually performed better than silica-based cables. In most cases, the attenuation was worse or the design was impractical.
But now, researchers from the University of Southampton and Microsoft claim to have made a breakthrough in HCF design in a recently study in Nature Photonics. The new fiber achieves a record low loss of 0.091 dB/km at 1,550 nm, compared to a 0.14 dB/km minimum loss for silica-based fibers. The new design maintains low losses of around 0.2 dB/km over a 66 THz bandwidth and boasts 45% faster transmission speeds.
The study authors explain, "Losses below 0.2 dB/km, compatible with long-distance communications, become possible from 700 nm to over ~2,400 nm. This offers the opportunity to optimize the transmission wavelengths of choice based on where optoelectronic components and amplification technologies present the best performance and achieve the lowest cost per bit, as well as the possibility to provide low-loss transmission at wavelengths that have been so far inaccessible."
Using advanced modeling, the researchers minimized three main loss mechanisms: leakage, surface scattering, and microbending, and tested fibers up to 15 km long to confirm their results. The new fiber is a kind of nested antiresonant nodeless hollow core fiber (DNANF) with a core of air surrounded by a meticulously engineered glass microstructure.
The team believes that further research can reduce losses even more, possibly down to 0.01 dB/km, and also help to tune the fiber for low-loss operation at different wavelengths. Even the losses achieved, however, open up the potential for longer unamplified spans in undersea and terrestrial cables and high-power laser delivery and sensing applications, among others.
The authors end by saying, "In light of the reported results, we are confident that, with advancements in produced volumes, geometrical consistency and reduced presence of absorbing gases in the core, DNANF HCFs will establish themselves as a pivotal waveguiding technology. This innovation has the potential to enable the next technological leap in data communications."
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More information: Marco Petrovich et al, Broadband optical fibre with an attenuation lower than 0.1 decibel per kilometre, Nature Photonics (2025).
Journal information: Nature Photonics
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