Prysmian Sirocco technology


Prysmian Sirocco technology

Prysmian experts share tech insights in the world’s densest optical cable – which has been proven to last more than 50 years.

The world’s densest fibre cable with a proven fifty-year+ lifespan

New and rigorous long-term ageing testing on the Sirocco family of cables, proving expected lifetime of more than 50 years, allowing operators to calculate the life cycle analysis of their networks over an extended period. Ian Griffiths, Global Digital Solutions R&D VP at Prysmian, explains… 

Prysmian’s Sirocco HD and Extreme cables are already well known as highly sustainable and extremely efficient solutions. Due to their extra-compact size and extreme fibre density, they’re easily deployable, make the most of limited duct space, require fewer raw materials and reduce transportation costs. Following optimisation of the optical fibre and materials, and rigorous testing, Sirocco cables are shown to have an expected lifetime of more than 50 years, without any compromise on performance during that time.

When evaluating optical fibre cable lifetimes, degradation from heat and water needs to be considered. In hot and dry environments, materials can undergo thermal degradation. In hot and wet environments materials such as PBT plastic and optical fibre coatings can undergo hydrolysis. The adhesive bond between the glass and primary coating is also susceptible to optical fibre coating failure, especially prevalent in wet environments or when the fibre is soaked in water.

After optimisation of the optical fibre and materials, rigorous testing took place that addresses all possible failure mechanisms that might occur out in the field. Cables were aged under both dry and wet ageing conditions while monitoring changes in optical fibre attenuation. Measurement of cable attenuation and other performance characteristics after lifetime simulation testing has verified that Sirocco microduct cables will function according to the ANSI/ICEA S-122-744 industry standard for optical cable outside plant microduct cables, even after a simulated lifetime exceeding 50 years, and under dry and wet ageing conditions. Conformant results relative to specified ICEA-744 requirements for unaged cables were achieved in all tests, even after long-term heat and humidity ageing, indicating that the lifetime simulation resulted in no measurable degradation of optical fibre, cable, or material function.

The test data demonstrates that the Sirocco range’s optical fibre attenuation, cable performance and material properties remain effectively unchanged and can easily meet industry specifications for newly manufactured cables.



Sirocco Extreme: thinner cables, higher density – without issues
Sirocco Extreme: thinner cables, higher density – without issues


Prysmian’s Sirocco Extreme microduct cables not only provide cost savings to network owners and builders but also enable them to reduce carbon and environmental footprints. The cables ensuring compatibility with existing G.652 fibres and readiness for evolved systems. Sirocco Extreme cables incorporate Prysmian’s PicoTube technology, making them up to 25% smaller than previously available microduct cables. This makes it possible to install more fibres into congested duct space and enables the use of smaller ducts for new installations, reducing installation costs and raw materials usage.

Deployment challenges, increasing bandwidth and latency requirements, and the need for higher densities are driving the need for smaller-size, bend-insensitive fibre cable. To reduce cable diameter, we can change a number of parameters, such as fibre size. Standard optical fibre is 250µm in diameter, but large segments of the market are now moving to reduced diameter 200µm fibres.

Micro bend resilience is essential for cables that will experience wide temperature variations, as these variations can induce material shrinkage. Micro bends are especially likely to occur within high-density cables, as fibres can touch each other due to tight packing, material shrinkage or other strain effects. While our bend-insensitive fibres were initially developed with macro bend insensitivity in mind, they also outperform all other fibre types for micro bend-insensitivity. Their microbending performance allows fibres to be packed much tighter together within the cable, with less risk of macro or micro bend losses. We’ve also developed coatings that are extremely thin without compromising performance, which also contributes to realising significantly higher densities. We also realise colour-coding by adding a secondary layer of coating, which already contains coloured pigments, which avoids using an additional layer of ink.

As fibre networks become more crowded, fibre bends are more likely to occur. Preventing power leakage with G.657 fibres is, therefore, crucial for optical systems with limited power budget. Bend resistance allows the use of smaller connectivity equipment such as loop guides and splice trays. In dynamic network environments, bend resistance also extends expected network lifetime by improving repair resilience. Smaller cables also provide sustainability benefits to the wider supply chain. These use less raw materials, and therefore use less CO2 in the manufacturing process. Additionally, as more cable can be supplied on the drum there are less truck rolls required and better cutting efficiencies. This can help reduce the environmental footprint, as well as lower costs.

Miniaturizing fibre cables and increasing cable density introduces several challenges, primarily related to physical, technical, and operational constraints. Sirocco cables’ ultra-compact design and high fibre density in a very small diameter cable are achieved through innovative manufacturing techniques and materials that allow for tight packing of fibres without risking damage or performance loss. The cables are constructed using materials that offer enhanced protection against environmental factors such as moisture, UV radiation, and extreme temperatures. Innovations in the structural design and materials used in Sirocco cables also contribute to improved mechanical performance, including better resistance to crushing, stretching, and other physical stresses that can occur during and after installation.

Use of wavelength division multiplexing (WDM) optics in PON and wireless networks are driving the need for bend-insensitive fibre in FTTX and 5G networks. Bend-insensitive single mode fibres (ITU-T G.657.A1 and G.657.A2) are the only fibres capable of securing the whole fibre spectrum, especially at the longer wavelengths (1625nm and above). These fibres enable the development of extreme fibre count and reduced diameter cabling solutions, so we can meet today’s demand for the highest bandwidth capacity in duct installations. Not only will we see benefits through faster and more stable optical networks, but installations will also become more cost effective, more environmentally friendly, all with lower operational costs as network lifespan increases thanks to higher repair resilience. The extreme fibre count and reduced diameter of these cables makes installation faster and more cost effective. Bend-insensitive fibre’s resilience gives manufacturers the ability to design cabling solutions which were previously impossible to create but are now demanded by today’s rapidly changing environments.

Report: Sirocco Cables expected lifetime greater than 50 years

“With the completion of this testing, it is now possible for operators to calculate the lifecycle analysis of their networks over a much longer period of time – more than 50 years. This contributes to minimizing waste and promoting a more sustainable approach to resource management, and will be critical for creating the long-lasting, high-performing networks of the future.”


Frederick Persson

Executive Vice President Digital Solutions at Prysmian