Microsoft and researchers in the UK have created advanced hollow-core fiber optic cables that carry data faster and farther than conventional fibers. These new fibers promise to meet the growing bandwidth demands of AI data centers and other high-speed applications.

Why Hollow-Core Fiber Matters

Standard fiber optic cables are incredibly fast, capable of transmitting hundreds of terabits per second. But as AI workloads expand, traditional fibers can’t keep up. Hollow-core fiber offers a solution because light travels faster through air than through glass.

The new design doubles the number of glass layers, forming a “double nested” structure that reduces signal loss and boosts transmission speed. According to the research team, bandwidth can increase up to three times compared to standard fibers, and data can travel distances of up to 33 kilometers—almost double that of conventional fiber.

How the Technology Works

The fiber’s structure is made of multiple concentric glass tubes that guide light through an air-filled core. This design, called double nested anti-resonant nodeless hollow-core fiber (DNANF), ensures that more than 99.995% of light travels through air rather than glass, minimizing distortion, delay, and energy loss.

“We can deliver signals faster and with fewer distortions,” says Francesco Poletti, chief scientist at Microsoft Azure Fiber and fiber optics professor at the University of Southampton. “The loss is well below what even the purest glass can achieve.”

Deployment and Industry Challenges

Despite the potential, replacing standard fiber is a major challenge. There are already over 5 billion kilometers of conventional fiber installed worldwide. Hollow-core fibers need their own ecosystem of connectors, splicers, and amplifiers.

Microsoft has begun deploying DNANF fibers between Azure data centers in Europe, using hybrid cables that combine hollow-core and single-mode fibers. With 1,280 kilometers already installed and carrying live traffic, the technology is proving its readiness for real-world use.

Scaling up production remains a hurdle. Drawing long lengths of hollow-core fiber is more difficult than standard fiber, and much of the process is still manual. Competition is also growing, with companies like China’s Yangtze Optical Fibre and Cable (YOFC) and Linfiber Technology reporting similar advancements.

The Future of High-Speed Data

Hollow-core fibers represent a major leap forward for data transmission. By reducing signal loss and increasing propagation speed, they are poised to play a key role in AI, cloud computing, and next-generation telecommunications.