Hollow core fibre (HCF) is a type of optical fibre where light travels mainly through an air-filled empty centre rather than through solid glass. This is a significant departure from conventional fibre-optic cables, where light propagates through a solid silica core.
Because light travels faster in air than in glass, hollow core fibre can reduce transmission latency by roughly 30% to 50% compared with traditional fibre. Conventional fibre typically introduces about 5 microseconds of delay per kilometre, while hollow core fibre can reduce this to around 3.3 to 3.5 microseconds per kilometre.
Instead of relying on the total internal reflection of a solid glass core, hollow core fibres use specially engineered glass structures surrounding the hollow region to keep the light confined. There are several methods available to manufacture HCF.
Advantages
Lower latency: Signals travel faster because most of the optical path is through air.
Reduced nonlinear effects: Less interaction between light and glass means fewer distortions at high power levels.
Potentially higher capacity: Wider usable optical spectrum and reduced impairments can support future high-capacity systems.
Lower signal loss potential: Recent research has demonstrated attenuation levels approaching or even surpassing conventional fibre in some cases.
Applications
Hollow core fibre is attracting interest for:
- Data centre interconnects
- AI and high-performance computing clusters
- Financial trading networks, where microseconds matter
- Telecommunications backbones & Subsea cables
- 5G/6G network infrastructure
Challenges
Manufacturing is more complex.
Splicing and installation require specialised techniques.
Costs are currently higher than conventional single-mode fibre.
For telecom operators, cloud providers, and AI data centres, the reduction in delay can translate into faster applications, better synchronisation, and improved performance across their large networks.
