Light and optical fibres
Light is the fastest and most powerful medium for data transmission: it takes just 1.3 seconds for a light pulse to travel from the earth to the moon. In order that light pulses can be transported over cables, an optical system is required: the optical fibre cable.
Optical fibres are fine fibres made of quartz glass. Despite their small diameter of only 0.125 millimetres, they transport around 5,000 times more data than copper cores with digital transmission. Fibre optic cables are also far superior in terms of cable properties. While conventional copper cables require a regenerator every three kilometres, fibre optics can carry information over 80 kilometres or more without amplification. In addition, they are practically insensitive to electromagnetic interference.
Glass fibres made from high-purity quartz glass
For data communication, glass fibres made of high-purity quartz glass are used. They consist of an optically denser core and an optically thinner jacket. Data transmission is based on the principle of total reflection at the interface between core and mantle. If a light beam is introduced at a certain angle into the optically denser core, it is not refracted at the transition to the optically thinner mantle, but completely reflected. The introduced light impulses can therefore only propagate in the core of the conductor and are guided within the fibre.