7. Fibre-optic cable

Copper cable is adequate for network cable runs for up to a 100 metres, but above that the signal becomes too weak, therefore an alternative technology is needed.

Fibre-optic cable has an astounding bandwidth, it is limited more by the electronics either side of the cable than the bandwidth of the cable itself. For instance in recent experiment, a 160 km length of high performance fibre-optic cable carried up to 14 Tera bits per second!

Fibre optic cable uses light to transmit information rather than electrical signals. Unlike copper cable it is not prone to electrical interference.

Fibre optic cable works by a light signal being 'launched' at one end of the glass thread core. The light is reflected internally down the fibre until it reaches the other end. Light sensitive electronics then pick up the signal.

The downside of fibre is the cost - it is more expensive that ordinary UTP network cable therefore it is only cost-effective if there is a very high bandwidth requirement or if the network has very long cable runs.

If fibre-optic could be laid from the telephone exchange right up to the house then broadband bandwidth of 100 Mbps is quite possible. A number of countries have now invested to make this a reality. Perhaps the UK may one day have fibre to every house as well.

At the moment fibre-to-cabinet is the norm in the UK, where it is fibre from the exchange to the nearest junction box, then normal copper cable to the home.