Researchers from the University of Southampton in the U.K. have teamed up with fiber engineers from Microsoft Azure to reduce attenuation in optical cables, where weakened signal power leads to data loss.

In a newly published paper in the Nature Photonics journal, the researchers contend that attenuation has improved only marginally over four decades, from 0.154 dB/km in 1985 to the current record of 0.1396 dB/km in 2024.

In traditional optical fiber deployments, the longer the route, the more light becomes scattered, and as a result, data is lost. Researchers have tried for decades to break attenuation limits of ~0.14 dB/km and ultimately make longer networks more efficient.

In their attempt, the engineering team turned their attention to hollow air core fiber, where only a minor portion of the optical power propagates in the solid fiber material (or very little light travels through the solid part of the fiber).

Their approach features a hollow air core surrounded by nested glass capillaries that guide light primarily through air rather than glass. This dramatically reduces scattering and absorption that would occur in traditional solid glass cores and cause signal power losses.

Tests recorded losses below 0.2 dB/km across an approximately 66 THz window. More notably, the team measured losses under 0.1 dB/km across the 1481-1625 nm band, with a record low of 0.091 dB/km at 1550 nm – a new low compared with the best solid-silica attenuation (~0.1396 dB/km).

The authors noted a ~30% latency reduction compared with conventional silica fibers, as light travels faster in air than in glass, which has the potential for their work to lower the latency of long-haul links.

In their latest paper, the researchers said results “pave the way for a potential revolution in optical communications, enabling unprecedented data transmission capacities, more energy-efficient optical networks and longer unamplified spans.”

"The approach theoretically supports further loss reductions and operation at wavelengths where broader bandwidth amplifiers exist, potentially heralding a new era in long-distance communications as well as remote delivery of laser beams,” the researchers wrote.

Despite the breakthrough, there are some issues with the concept, chiefly the increased core diameters of the glass microstructure, resulting in fiber cables being “less bendable.”

Beyond their efforts, they found that simulations where the structure makes the fiber even stiffer could result in an even further reduction of signal loss, though further testing would be required to confirm this.