Advances in optical communications

Citation

Rudall, B.H. (1998), "Advances in optical communications", Kybernetes, Vol. 27 No. 4. https://doi.org/10.1108/k.1998.06727daa.008

Advances in optical communications

Advances in optical communications

A research report in the UK's Engineering and Physical Sciences Research Council (EPSRC) information technology update, Impact, No. 17, 1997 described pioneering work at Aston University in optical communications. The work has demonstrated the immense potential of solitons, an important innovation in optical telecommunications and processing.

Solitons are short, particle-like pulses which can be used to exploit the non-linearity inherent in fibre-optic transmission. They create a distinctive wave form which is more stable and less subject to fibre degrading effects, such as dispersion, than traditional optical techniques.

Professor Nick Doran of the Aston Photonics Group (APC) is quoted as saying that:

These characteristics make solitons the natural digital solution. This holds the key to the next major increase in practical fibre optic speeds over long distances, such as on transcontinental networks. We also expect the ability to use solitons to merge transmission with aspects of processing will have a profound effect on broader areas of network design and all-optical communications systems.

The research report says that solitons have been known about since the 1980s. Their take up, however, has been inhibited by practical problems, such as the "jitter" caused by instabilities in pulse transmission.

The research at Aston University is led by Professor Doran and Ian Bennion and has focused on overcoming such problems in order to optimise the capacity and distance of amplified soliton communications, particularly using existing fibre technology. Innovations in the dispersion management control of solitons have been among the APG's main contributions to achieving this. For example, its "uniform finite dispersion" approach produced a very small overall dispersion by transmitting solitons along transmission paths with alternating positive and negative dispersion. This can almost completely eliminate jitter, including that encountered in systems transmitting multiple data stream at different wavelengths simultaneously.

This research group has also been at the forefront of developing "fibre grating" reflective filters for dispersion compensation, including "chirped" fibre grating that can change the pitch of soliton waves.

The Aston team has already demonstrated the success of this work by setting a world record for soliton transmission on standard optical fibres. Using their amplified recirculating loop, this showed that speeds of 10 Gbps could be reached with installed fibre for distances of up to 10,000 kilometres.

The proof of the importance of the group's contributions to this field is demonstrated by the adoption by industry of their initial identification of the principles of soliton system design which is based on pulse duration and amplifier spacing.

APG is also active at the leading edge of many other photonics disciplines, such as the formulation and application of modelling theory and network developments. The major telecommunications companies such as British Telecom (BT), BNR Europe, GPT, STC, and GMMT have strong working links with the Aston Group.

Details of their work are also available on the Web link: http://www.benedick.aston.ac.uk/Photonics/ (Aston Photonics Group UK).

B.H. RudallNorbert Wiener Institute and the University of Wales (UK)