Light and optical cables
Light is the fastest and most powerful medium for data transmission: a light pulse needs only 1.3 seconds to travel the distance from the earth to the moon. In order to transport light pulses in cables, an optical system is required; the fibre-optic cable.
Fibre-optical cables are made of fine fibres of quartz glass. Despite their small diameter of only 0.125 millimeters, they transport 5000 times more data than copper cables. Fibre optics also have superior transmission properties. While a regenerator is required every three kilometers when using conventional copper cables, fibre-optics can carry information over 80 km without amplification. Moreover, they are insensitive to electromagnetic interference.➔ more
High-purity fused silica glass fibres are used for data communication. They consist of a denser optical core and a thinner cladding. The data transfer relies on the principle of total internal reflection at the border between core and cladding. A beam of light is introduced at a certain angle to the denser core, and where it crosses to the cladding it is reflected not refracted. These induced light pulses can only move forward within the core of the cable.
Every fibre in a fibre-optic cable can transport large amounts of data (for example, thousands of phone calls at the same time). In order to fully exploit this capacity, special transfer technologies are needed. These allow for the transmission of eight million pages worth of data per second in a cable with 40 fibres. Additional developpments in technology, such as wavelength division multiplexing (WDM), allows for multiple spectrums of light with different wavelengths to be transmitted in parallel. With spectrums becoming denser and denser the fibre optical technology is futureproof and can help satisfy the growing bandwidth needs of our society.