In the relentless race to define the future of the internet’s infrastructure, an esoteric breakthrough has nudged the UK and Microsoft into center stage: hollow core fibre (HCF) technology. Though fibre optic cables are the backbone of today’s digital world, their essential design—glass transmitting light—has been largely unchanged for decades. HCF’s audacious reimagining, replacing glass with an air-filled core, promises a generational leap for ultra-high-speed, ultra-low-latency networks. With its commercial leader Lumenisity (now Microsoft Azure Fibre) shortlisted for the 2025 MacRobert Award—the UK’s most prestigious engineering accolade—this is no mere research curiosity. The implications for cloud computing, financial markets, and even quantum computing are difficult to overstate.
Standard fibre optics use ultra-pure glass to transmit laser light, guiding packets of information across continents and oceans. While advances have improved bandwidth and network management, the glass itself imposes immutable physical limits. Light traveling through glass moves slower than through air, and, crucially, interacts with the fibre’s atomic structure, introducing losses, dispersion, and signal distortion.
Hollow Core Fibre turns this convention on its head. Instead of a solid core, these fibres use a sophisticated structure of air channels—sometimes as little as a single air-filled core—surrounded by a delicate lattice of glass. The result? Light travels primarily through air, not glass, lowering latency (the time information takes to travel) and dramatically reducing the loss and distortion that plague even the best conventional fibres.
Microsoft’s acquisition of Lumenisity in late 2022 marked the coming of age for HCF, integrating the technology directly into Azure’s cloud infrastructure under the “Microsoft Azure Fibre” banner. Dr. David Parker, a key figure in both Lumenisity and its new Azure manifestation, summed up the journey: transforming “hollow core optical fibre technology from an academic concept... achieving world record performance, fully commercialising it as a cable solution... and now utilising it to enhance the performance and operation within Microsoft Azure’s Cloud Infrastructure, has been an incredible journey for our entire team” (as quoted in Thinkbroadband).
Most independent sources agree: HCF has reached the point where it’s deployable, at scale, for specialized, high-value applications. Microsoft’s public deployment in Azure and high-profile customers in finance underpin its credibility.
Organizations at the bleeding edge—whether trading in global financial markets, running petabyte-scale AI, or future-proofing national cloud infrastructure—are already gambling that HCF will pay off. For everyone else, this technology is one upgrade cycle away from becoming tomorrow’s new normal.
Source: Thinkbroadband Hollow core fibre technology shortlisted for MacRobert Award
What is Hollow Core Fibre?
Standard fibre optics use ultra-pure glass to transmit laser light, guiding packets of information across continents and oceans. While advances have improved bandwidth and network management, the glass itself imposes immutable physical limits. Light traveling through glass moves slower than through air, and, crucially, interacts with the fibre’s atomic structure, introducing losses, dispersion, and signal distortion.Hollow Core Fibre turns this convention on its head. Instead of a solid core, these fibres use a sophisticated structure of air channels—sometimes as little as a single air-filled core—surrounded by a delicate lattice of glass. The result? Light travels primarily through air, not glass, lowering latency (the time information takes to travel) and dramatically reducing the loss and distortion that plague even the best conventional fibres.
The Physics
- Speed of Light Advantage: Light travels about 50% faster in air than in glass. While normal fibre limits light to roughly 200,000 km/s, hollow core approaches the true speed of light in vacuum (299,792 km/s). This drop in latency—measured in microseconds per kilometer—turns into a significant competitive edge at scale.
- Reduced Interference and Loss: By minimizing light-glass interactions, HCF slashes both absorption losses and non-linear effects. This leads not just to lower transmission losses but also allows ultra-fast signals to maintain their integrity over much longer distances.
Commercial Maturity: From Academic Breakthrough to Azure
While hollow core fibre was once regarded as a high-risk academic experiment, the past few years have seen it transition into a commercially viable product. Lumenisity—a spin-out from the University of Southampton’s world-leading optics research—achieved several world records in transmission performance and transformed the concept into a robust, factory-produced cable.Microsoft’s acquisition of Lumenisity in late 2022 marked the coming of age for HCF, integrating the technology directly into Azure’s cloud infrastructure under the “Microsoft Azure Fibre” banner. Dr. David Parker, a key figure in both Lumenisity and its new Azure manifestation, summed up the journey: transforming “hollow core optical fibre technology from an academic concept... achieving world record performance, fully commercialising it as a cable solution... and now utilising it to enhance the performance and operation within Microsoft Azure’s Cloud Infrastructure, has been an incredible journey for our entire team” (as quoted in Thinkbroadband).
Why Does Hollow Core Matter?
Latency: The Ultimate Differentiator
For many digital experiences—video streaming, public cloud, basic web browsing—shaving a few milliseconds off data transit times is not critical. But large swathes of the global economy are becoming latency-obsessed:- High Frequency Trading (HFT): Financial institutions pay astronomical sums for even marginal latency improvements, as faster connections can mean the difference between profit and loss in algorithmic trading environments.
- Quantum Computing and AI: As quantum computers and high-performance AI clusters proliferate in the cloud, the inter-node communication speed becomes a bottleneck. HCF can reduce this latency, supporting the distributed, data-hungry workloads of tomorrow.
- Global Cloud Infrastructure: Data centers rely on multi-terabit connectivity. Lower latency and longer reach before signal regeneration reduces both costs and complexity, powering new levels of cloud elasticity and global data flows.
Loss Reduction and Fewer Repeaters
Another critical advantage is reduced signal loss over distance. Traditional fibres require periodic optical amplifiers or repeaters—expensive, power-hungry nodes that boost the signal but add cost, maintenance complexity, and, paradoxically, further latency. HCF’s superior performance means fewer such repeaters are required, lowering operational expenditures and improving uptime.Potential for New Services
- Real-time Global Applications: From telemedicine to industrial IoT, the ability to exchange data in near real-time across continents could unlock applications that previously were impossible due to time-lag.
- Hybrid Cloud and On-Premise Integration: Enterprises are increasingly blending cloud and local processing. Reliable, ultra-low-latency interconnects will enable new architectures for everything from banking to gaming to autonomous vehicles.
The MacRobert Award: A Testament to Engineering
The Royal Academy of Engineering’s MacRobert Award represents more than just a nod from the scientific establishment—it has a storied history of highlighting UK innovations that reshape industries. Previous winners include the CT scanner and the Raspberry Pi. In 2025, alongside OrganOx and Synthesia, Microsoft Azure Fibre’s HCF technology stands out for its direct impact on the most critical digital infrastructure.Verification and Industry Validation
Several key claims about hollow core fibre’s properties have now been verified in independent tests and peer-reviewed publications:| Property | Standard Fibre (Silica) | Hollow Core Fibre (HCF) | Industry Verification |
|---|---|---|---|
| Group Velocity | ~0.67c | ~0.97c | University of Southampton, Microsoft Research |
| Typical Latency/km | ~5.0 µs | ~3.0 µs | Published in Nature, verified by BT and Microsoft joint trials |
| Loss (dB/km) | 0.16 – 0.18 | Now <0.22 (down from >1dB) | Real-world trials, Thinkbroadband, Lumenisity whitepapers |
| Signal Integrity | Subject to non-linearities | Minimal distortion | Customer POCs in finance/trading |
Competitive and Strategic Implications
Microsoft’s Strategic Rationale
The acquisition of Lumenisity and the subsequent shift to Azure branding cement Microsoft’s commitment to dominating not just the software or cloud service layers but also the physical fabric of the network. By embedding HCF within Azure’s backbone, Microsoft not only signals to enterprise and government customers that their networks can operate with leading-edge performance, but it also opens the door to a new generation of global, enterprise-grade cloud services that competitors may struggle to match.Broader Sectoral Impact
- Telecommunications: Telecom giants are investing in early deployments to see if HCF’s higher bandwidth and lower cost-of-ownership can revolutionize their own core networks.
- Financial Services: User trials with major exchanges and trading floors have demonstrated tangible advantages, with some institutions already adopting HCF links between their data centers.
- Scientific and Research Computing: With the acceleration of climate modeling, genomics, and physics simulations, ultra-fast, low-loss connections are essential for real-time collaboration and distributed cloud clusters.
Strengths
- Step-Change in Latency: HCF offers the first meaningful reduction in light-speed delay since optical fibre was invented—a genuine leap.
- Commercial-Ready: Early concerns over fragility, manufacturability, and cost have been substantially addressed. Robust cables, protectively jacketed and compatible with standard networking hardware, are already shipping to customers.
- Integration with Public Cloud: By being the first to offer HCF-powered services in a mainstream cloud product (Azure), Microsoft leverages both first-mover advantage and network effects, accelerating real-world adoption.
Potential Risks and Uncertainties
- Deployment Cost and Retrofits: While HCF can be deployed in new routes, retrofitting existing in-use fibre trunk lines is an expensive and logistically daunting task. Early adoption is concentrated in new builds and highly latency-sensitive sectors.
- Compatibility and Standardization: Ensuring that HCF can seamlessly interoperate with legacy networking equipment is still a work in progress. Some edge-case network functions and diagnostics may require updates or replacements.
- Scaling Beyond Niche Use: The business case for mass rollout hinges on further reductions in production and installation cost, as well as expanded standardization—factors that are advancing quickly but not guaranteed to hit consumer-level pricing soon.
- Long-Term Durability: While laboratory and early field data is extremely promising, decades-long durability and environmental resilience are still being validated against the built-in reliability of traditional fibre.
Looking Ahead: The Future Role of Hollow Core in Cloud, Quantum, and AI
The shortlisting for the MacRobert Award spotlights HCF’s place as a generational inflection point in the engineering of the Internet. While true mass-market displacement of conventional fibre may still be years off, the technology’s commercial breakout is already redefining what’s possible at the cutting edge.- Quantum Networking: Researchers are already exploring HCF as an ideal medium for quantum key distribution, given its ultra-low noise and minimal signal decoherence. A secure, global quantum backbone could finally be feasible.
- Cloud-Native Enterprises: As businesses embrace distributed ledgers, real-time AI, and zero-trust architectures, the need for near-instantaneous global data exchange will only grow. HCF stands ready to meet this challenge.
The UK’s Engineering Edge
In a field often dominated by the United States and East Asia, the rise of a UK-born technology, nurtured by academic and industrial partnerships, is remarkable. Lumenisity’s journey from university lab to global infrastructure contender reflects the enduring importance of public investment and long-term R&D in producing world-class innovation.Conclusion: Just the Beginning
Hollow core fibre is no panacea—but it’s a pivotal new tool, and one that could soon underpin the “next generation of the fabric of the internet.” Whether or not it claims the MacRobert Award, HCF has already joined the rarefied set of engineering innovations that shift technological limits for everyone else. By slashing latency, extending bandwidth, and readying itself for the uncharted demands of quantum and AI-powered workloads, it guarantees one thing: in the ongoing race to push digital transformation, the signal is now moving faster than ever before.Organizations at the bleeding edge—whether trading in global financial markets, running petabyte-scale AI, or future-proofing national cloud infrastructure—are already gambling that HCF will pay off. For everyone else, this technology is one upgrade cycle away from becoming tomorrow’s new normal.
Source: Thinkbroadband Hollow core fibre technology shortlisted for MacRobert Award
