AMANDA SPRINGMANN ULTRA-THIN FIBRE
ULTRA-THIN FIBRE: WHY IT MATTERS FOR DUCTS,
DATA CENTRES, AND SUSTAINABILITY Network build teams are being squeezed from all sides. There’s a growing demand for fibre, to keep up with FTTH expansion and AI-driven data-centre growth. However, they also need to consider the physical limits of ducts, risers, trays, manholes and patching space to consider – as well as environmental factors. Ultra-thin fibres, currently available as slim as 160µm, can provide a solution, writes Prysmian Datacenter Business Development Director Amanda Springmann . E xactly what is an ‘ultra-thin’ fibre? In almost all modern single-mode fibre, the glass diameter remains 125µm. What changes is the diameter of the polymer coating - are not optimised. Extending the optical field width at higher wavelengths makes the fibre more sensitive to bending. This ended up in the ITU-T Recommendations and IEC standards with the current requirement of a maximum added loss of 0.1 dB at 1625 nm for 100 turns with a 30 mm radius. But fibre optic networks are a long- term investment, and solutions must be considered carefully. When selecting a solution, it is essential that it is fully compliant with G.652 and G.657.A2, compatible with legacy single- mode fibre, and capable of supporting
the protective layer. That introduces a significant geometry benefit: the cross- sectional area is reduced by more than half compared to traditional 250µm fibres, enabling smaller, higher-count cable designs. These are ideal for constrained spaces such as underground ducts, POPs, edge facilities, buildings, and data centres. New cabling systems with a high degree of fibre density offer a rapidly deployable, more reliable, more cost-effective solution. However, there is an engineering catch: shrinking the fibre can increase the risk of microbend issues. As cable cores become denser and diameters shrink, fibres experience tighter routing and higher local pressures. These conditions increase macro- and micro-bending losses if the fibre and coating system
tight bends and mechanical reliability. Fibres as slim as 160µm only become useful at scale if bend performance remains robust. Otherwise, density gains will be offset by tighter loss budgets, extra handling constraints, or operational variability. SUSTAINABILITY BENEFITS Reducing cabling diameter can cut plastic and carbon. There is a direct materials reduction. A thinner coating uses less polymer per fibre-km. With 125µm glass: • 200µm coating, with polymer cross- section area proportional to π (100² − 62.5²) • 160µm coating, with polymer cross- section area proportional to π (80² − 62.5²) That works out to ~59% less coating polymer area going from 200µm to 160µm. The glass stays constant and only the polymer is reduced. At the “total fibre” cross-section level, 160 vs 200 is 36% less area (160/200)² = 0.64 ). Reduced coating diameter can reduce plastic demand—especially meaningful when multiplied across hundreds to thousands
Therefore, correctly specified bend- insensitive fibre cables are crucial for the shift towards flexible and reliable connectivity. With their extreme fibre count and reduced diameter, they also make installation faster and more cost effective. Bend resistance allows the use of smaller loop guides upon installation and reduces the bend radius of splice trays: connectivity devices become smaller, saving even more space. In dynamic network environments, bend resistance can also extend the expected network lifetime by improving repair resilience. Next-generation WDM-PON drives the need for bend-insensitive fibres as part of FTTx and 5G mobile networks.
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| ISSUE 43 | Q1 2026
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