University of Southampton achieves record-low signal loss with Hollow Core Fibre (HCF) technology on Microsoft Azure

In a major leap forward for global communications, researchers from the University of Southampton have developed a novel optical fibre design that demonstrates significant improvements in speed, efficiency, and data capacity. The design was developed with collaboration from Microsoft Azure Fiber researchers.

Published in Nature Photonics earlier this month, the breakthrough introduces a fibre that guides light through a hollow core of air, rather than traditional solid glass, achieving the lowest signal loss ever recorded and enabling faster, more energy-efficient data transmission over long distances.

“This is a breakthrough in how we transmit information”, said Professor Francesco Poletti, Professorial Fellow at the University of Southampton and Chief Scientist at Microsoft Azure Fiber. “For decades, the performance of optical fibres has remained largely unchanged. This new fibre design breaks through that barrier, demonstrating the potential for faster data transmission, lower energy use, and the ability to carry much more data. It’s a fundamental shift in global connectivity. This result is the pinnacle of over 10 years of research and development, made possible by the ingenuity, collaboration and dedication of an interdisciplinary team working across Microsoft and the University of Southampton.”

At the heart of this innovation is the Double Nested Antiresonant Nodeless Hollow Core Fibre (DNANF), a sophisticated structure invented by researchers at the Optoelectronics Research Centre (ORC) at the University of Southampton and Microsoft Azure Fiber. These fibres feature a central hollow core surrounded by ultra-thin glass membranes arranged in nested layers, and allow light to travel primarily through air, dramatically reducing the scattering and absorption that limit conventional fibres.

To put this in perspective: in the new DNANF fibre, light can travel 33km before its power is reduced by half. In contrast, standard telecom fibres, typically with a loss of around 0.2 dB/km, reach only 15km before experiencing the same reduction. This means the new fibre can more than double the transmission distance without needing amplification, unlocking the potential to cut future energy use and infrastructure costs. 

Why it matters 

“These advances in ultra-low-loss HCF will let Microsoft transmit more data with less power and dramatically lower latency across our global network,” said Jamie Gaudette, Partner Network Engineering Manager at Microsoft. “Together, with the team at the University of Southampton, Azure is redefining the physical layer to deliver a faster, more reliable and cost-efficient cloud experience to Customers worldwide.”

Key benefits once the technology is deployed at scale:

• Faster: Approximately 47% faster, reducing latency, powering real-time AI inference, cloud gaming and other interactive workloads.
• Greener: Lower signal loss means fewer amplifiers, cutting energy use and carbon footprint.
• More Capacity: A wider optical spectrum window enables exponentially greater bandwidth.
• Future-Ready: Lays the groundwork for quantum-secure links, quantum computing infrastructure, advanced sensing and remote laser delivery. 

A New Era in Fibre Optics

For over 40 years, traditional glass-based fibres have been constrained by how much light they lose over long distances. DNANF fibres change that paradigm. By guiding light through air with unprecedented precision, they offer ultra-low loss across a wide range of wavelengths, more than double the usable spectrum of conventional fibres.

The researchers believe this technology could become the backbone of future internet infrastructure, while also transforming data centre connectivity and cloud services. 

Read the article: ‘Broadband optical fibre with an attenuation lower than 0.1 decibel per kilometre’.