AsianFin — Researchers supported by Microsoft have unveiled a groundbreaking hollow-core optical fiber that achieves the lowest signal attenuation ever recorded, marking a major breakthrough in optical communication technology. The results were published on September 1 in the prestigious journal Nature Photonics.

Unlike traditional solid-core fibers that use a glass core to guide light, hollow-core fibers feature a central air channel surrounded by multiple concentric layers of micrometer-thick glass tubes. These tube walls act like miniature mirrors, reflecting light back into the air channel while suppressing higher-order modes. By replacing solid glass with air, inert gas, or even vacuum as the transmission medium, the fibers experience dramatically reduced absorption and scattering losses.

Historically, hollow-core fibers have been conceptualized since the 1960s but were hindered by technical limitations. Earlier designs suffered from high light leakage, with losses exceeding 1 dB/km, making them impractical for long-distance communications. The new design by Microsoft’s Lumenisity research team overcomes these challenges using a dual-layer nested anti-resonant nodeless fiber (DNANF) structure, wrapped in finely tuned silica rings. This design leverages the photonic bandgap effect to confine light effectively in the air core, minimizing interactions with material surfaces.

At a wavelength of 1,550 nanometers, the team achieved a signal attenuation of just 0.091 dB/km, surpassing the 0.14 dB/km limit of conventional silica fibers. Researchers described the achievement as one of the most significant advances in waveguide technology in the past four decades.