Agtec Telecoms - An Introduction to Fibreflow

Fibreflow Blown Fibre takes the form of an ultra-lightweight single bundle of optic fibres designed for the access network ('The Last Mile') or campus. The fibre bundle is blown into a miniature duct system, using airflow, that takes it all the way to the customer premises without splicing along the way.

Disadvantages of traditional cables
Installation of cables underground has often subjected them to high pulling forces, as they are pulled into ducts by pulling machines.
Since optical glass cannot survive more than a few percent elongation, it has to be protected from high pulling forces. Even forces that do not cause fibre damage can reduce fibre lifetime significantly, and this makes low tension, low strain fibre installation all the more important if the fibres are not going to fail in their first year or so.

Strength members in traditional optical cables may be steel ropes, glass-reinforced rods or tapes, or aramid yarns. These make optical cables heavy, bulky, stiff, expensive, and increase stripping and handling time.
They are not required in blown fibre units, since the fibre unit is blown in stress-free, after the 'empty' cable has been installed.

Fibreflow bundles are installed with no fibres inside
Installing 'empty' cables removes the need for tension control, and also the worry about fibres that will not be 'lit' for a long time. A large proportion of fibres in traditional fibre cables are still not active, and so delay investment payback.

Using just airflow to install fibre into pre-installed microducts exposes fibre to almost zero stress, and so no reinforcement of the fibre is needed. For the multi-branching access network, this is a big technical advance. And fibre lifetime is preserved in full.

A fibre element with individual fibres stripped out.

There is no sticky gel to remove.

It is clear that such a simple fibre element has many advantages over 'standard' optical cables, and fibreflow is already sweeping away the idea that Fibre To The Home is costly and not viable.

Air-blown fibre is a method of installing fibre optic cables that relies on the flow of compressed air easing the fibre all the way to its destination - sometimes 1km away. A set of rollers or caterpillar drive typically feeds the fibre into the microduct.

Ideally suited to the Access Network ('The Last Mile') which compared to trunk routes has traditionally been difficult to plan due to intricacies of route and intermittent customer uptake. It was difficult to justify 24 fibres down a residential street if only 3 houses needed immediate connection. With blown fibre systems like fibreflow, a low-cost microduct route is installed, and fibre only added as and when it is needed, creating a fibre-lean solution. And when a new connection is required, there is no need to re-dig the street, just select an empty microduct and blow fibre in.

Fibreflow air-blown systems are replacing traditional optics in access networks around the world.
The benefits include:

•Optical and mechanical:
•Mode field diameter at 1310 nm	[μm]	9.2 ± 0.4
•Cladding diameter	[μm]	125.0 ± 0.7
•Coating diameter	[μm]	245 ± 5
•Typical attenuation at 1310 nm	[dB/km]	≤ 0.36
•Typical attenuation at 1550 nm	[dB/km]	≤ 0.22
•Typical attenuation at 1383 nm	[dB/km]	≤ 0.36
•Dispersion in the range 1285 to 1330 nm	[ps/(nm*km)]	≤ 3.5
•Dispersion at 1550 nm	[ps/(nm*km)]	≤ 18
•Cable cutoff Wavelength (λcc)	[nm]	≤ 1260
•The fibers are fully in compliance with ITU G.652.D and annexes. •Other options are available on request.

Characteristics of fibers E9/125 SMF 28e™ - low water peak fiber -

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