Faster data down the fibre

A research team from Essex University claims to have developed a data transmission method which can achieve world-record telecommunications data rates.

A research team, led by Dr. Stuart Walker from Essex University, claims to have developed a data transmission method which can achieve world-record telecommunications data rates, of over a terabit (one trillion binary digits) per second, on multimode optical fibres which already exist in the majority of in-building communications networks throughout the world.

Dr. Walker is presenting the world record transmission concept on Thursday September 5 at Photon 2002 in Cardiff in Wales. His scheme combines the data transmission techniques commonly used in communications networks to allow many signals to travel simultaneously along a fibre optic cable.

Traditional networks send a number of single data transmission signals along fibre optic cables at the same time. This is possible as each signal occupies a different part or wavelength of the light spectrum.

Dr. Walker’s team uses subcarrier signals, which consist of two data signals on top of each other occupying the same wavelength, making two signals appear as one.

The scheme combines many of these subcarrier signals onto the same transmission path, allowing all of them to travel down the cable on the same wavelength. This means that where traditionally only one signal could occupy one wavelength, many signals can now occupy that single wavelength.

By using this technique on all available wavelengths, the group’s preliminary experiments showed that a data rate of 1.02 terabits per second could be achieved over a distance of up to 3km on conventional multimode fibre.

As the number of Internet users continues to grow and users demand more bandwidth, to run faster programmes, the data transfer requirements of local area networks (LANs) are steadily growing. As the majority of these existing LANs use multimode fibre already, the team’s work could save telecommunications companies money by allowing them to increase the data traffic on their existing networks, instead of laying new more expensive fibre.