Fibre optic cables contain fibre optics which are a medium to transmit a signal, in this case, electromagnetic wave in the infrared range. As such, they are resistant to electromagnetic interference, and their special feature is the ability to transfer data with huge throughput, up to hundreds of Gib/s.
Detailed construction of a fibre optic cable depends on the specific application (method and place of installation, and a distance at which transmission will occur), but in general, there are several components:
- optional central element
- fibre optic
- protective tube
- external shell
Depending on the number of sent fibre optic modes (waves), fibre optics are divided into single-mode and multi-mode.
Single-mode optic fibres are characterized with low dispersion and attenuation, making them suitable for transmission at long distances. Due to the minimum attenuation, in telecommunications a wavelength of 1550 nm (III transmission window) and 1310 nm (II transmission window) are used to transmission. Single-mode fibre optics allow to transmit in xWDM technology, which allows to achieve throughput of Tib/s.
In the literature and fibre optic cables specificatione one can meet the following designations of single-mode fibres: 9/125, SM, G.652, G.653, G. 655, G. 657 A, G. 657 B. In the fibre optic cables produced by TELE-FONIKA Kable, these type fibres are marked with J (fibred with unmoved dispersion), and Jn (fibres with non-zero dispersion).
Multi-mode fibres carry a number of light modes. Because of the dispersion, they are mainly used to transmit at a short distance, e.g. within one building. The wavelength of 850 nm and 1300 nm are used to throughput.
Marks of the multi-mode cables include a diameter of the fibre core and a covering protective layer (so-called coat), e.g. fibre marked as 50/125 has a core with a diameter of 50 μm and a coat with a diameter of 125 μm. G 50 mark is used alternatively. 62.5/125 is another common multi-mode fibre, alternatively marked as G 62.5.
Due to the construction and application of fibre optic cables, they can be divided into:
internal - used inside buildings or structures, e.g. tunnels
external - used outside buildings. This category includes self-supporting cables, cables used in sewerage system, and cables of special applications.
universal - due to their design, they can be used both in internal and external systems