5 Minutes
New fiber design that redirects light through air
Researchers have engineered a new class of optical fiber that replaces the conventional solid silica core with a hollow air core surrounded by a precisely structured glass microstructure. This hollow‑core, microstructured fiber guides light with substantially lower attenuation and a broader transmission window than standard solid‑glass fibers, potentially extending the distance optical signals can travel before amplification is required and increasing the usable data capacity of long‑haul links.
Scientific background and why it matters for telecommunications
Conventional single‑mode optical fibers used in telecommunications are built around a solid silica glass core. Over decades of material and design improvements, these fibers have become highly optimized, but intrinsic absorption and scattering in the glass still cause signal loss. In practical networks this loss means optical amplifiers must be placed every tens of kilometers — for many standard fibers roughly every 20 km half the injected light power may be lost — driving cost, power consumption and complexity for terrestrial, subsea and intercontinental links.
Hollow‑core fibers minimize light interaction with solid glass by confining most of the guided mode to low‑loss air. Because air has much lower absorption and scattering at telecom wavelengths than glass, hollow‑core designs can substantially reduce attenuation across a wider spectral range. A broader low‑loss transmission window also allows more wavelength channels to be used simultaneously, increasing raw data throughput via wavelength‑division multiplexing (WDM).
Experiment details and key measurements
Led by Francesco Poletti at the University of Southampton, the team fabricated a microstructured waveguide consisting of a hollow central channel surrounded by a pattern of thin silica rings. In controlled laboratory tests the fiber achieved an optical attenuation as low as 0.091 dB/km at a commonly used telecom wavelength — a loss figure that corresponds to signals traveling roughly 50% farther between amplification stations compared with many legacy solid‑core fibers.
Beyond the low attenuation, the new fiber shows a much broader transmission window (the range of wavelengths with low loss and low distortion), enabling wider broadband operation and potentially supporting higher aggregate data rates. The authors also note that increasing the air‑core diameter could further reduce losses, although that approach requires additional engineering to preserve modal stability and manufacturability.
Design trade‑offs and manufacturing
Hollow‑core microstructured fibers demand high geometric precision and control of internal gases: residual absorbing molecules inside the hollow core can raise loss, and production tolerances affect mode confinement and bandwidth. Scaling from lab proof‑of‑concept to kilometer‑scale fiber reels will require advances in draw processes, quality control and gas handling.
Implications for networks, data centers and subsea cables
If industrialized, hollow‑core fibers could reduce the number of optical amplifiers required on long links, lowering energy use and operational cost. The expanded transmission window is attractive for next‑generation dense WDM systems, offering operators increased spectral efficiency and headroom for future traffic growth driven by cloud services, 5G/6G backhaul and high‑definition content delivery.
These fibers are also relevant to precision timing and quantum communication systems, where lower latency and reduced phase noise from less glass interaction can improve link fidelity.
Expert Insight
Dr. Mira Alvarez, optical systems engineer (fictional), commented: "Hollow‑core approaches are one of the most promising routes to break current limits on loss and bandwidth. The Southampton team's sub‑0.1 dB/km result is encouraging — but the real test will be reliable, large‑volume manufacture and field trials under variable environmental conditions. If those hurdles are cleared, telecom operators could re‑architect long‑haul trunks with fewer amplifiers and much lower power consumption."
Future prospects and next steps
The authors suggest that improved geometrical consistency, higher production volumes and elimination of absorbing gases inside the core will further drive down attenuation and improve yield. Subsequent work will likely focus on scaling fiber draws to industrial lengths, demonstrating splice compatibility with existing fiber infrastructure, and field testing in terrestrial and subsea environments. The research appears in Nature Photonics and sets a roadmap toward integrating hollow‑core microstructured fibers into commercial optical networks.
Conclusion
Hollow‑core microstructured optical fibers offer a compelling combination of lower loss and wider bandwidth that could materially improve long‑distance telecommunications. By guiding light largely through air rather than glass, these fibers can extend amplifier spacing, increase spectral capacity and reduce energy consumption on critical backbone and subsea links. While manufacturing and integration challenges remain, the technology represents a promising direction for the next generation of global optical communications.
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