Which optical cable to choose according to your FTTP architecture?

The subscribers’ connection to very high speed networks is performed by telecom network engineers with the use of various FTTP solutions. FTTP cabling is needed to link different optical points, e.g. to connect an OTO to the ISP box. Choosing the right fibre optic cable is not an easy job: depending on the cable mode, its structure and the type of connectors, the choice of an optical cable can be made among different types.

The selection of an optical jumper involves various steps:

Etape 1 – Choisir le type de fibre optique

The mode corresponds to the transmission mode of the optical light: this can be singlemode or multimode.

A multimode cable enables several light modes to pass through so to transmit different data. The OM1 structure has a 62.5 micron optical core while the OM2, OM3 and OM4 structures have a 50 micron optical core.

OM1 and OM2 optical cords are generally used for short distance Ethernet networks: these are fibre optic older generations, orange coloured. OM3 and OM4 are more commonly used today and support higher data rates over longer distances. They are turquoise and magenta, respectively.

A singlemode cable, with its 9-micron optical core, offers much higher performances than multimode fibres. Yellow coloured, these cables are mainly used for telecom applications such as the rollout of high-speed networks over large areas.

Step 2 – Choosing the cable type

Whether multimode or singlemode, the optical cable comes in simplex or duplex versions depending on the intended use. The simplex version consists of a single fibre core, whereas the duplex version presents two. As simplex fibre is based on a single fibre optic, it allows data to be transferred in one direction at high speeds. Duplex fibre, on the other hand, allows for bi-directional data communication and is ideal for telecommunications applications.

Step 3 – Choosing the cable structure

There are two fibre optic structures: tight buffered and loose tube. In the case of tight buffered structure, all the fibres are covered with a plastic layer that increases the outer diameter from 250 to 900 microns. In the case of a loose tube structure, fibres are enclosed by a tube, in packs of 4 to 24.

For fibre optic tight buffered structures, the optical connectors are easier to assemble. Indeed, they are to be mounted directly on the fibre, whereas in the case of a loose tube structure, pigtails are needed, so the connectorisation requires various tools such as splice trays and a fibre optic fusion splicer.