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 Monday, 13 November 2006
A major step towards dynamic and reconfigurable ‘smart’ networks has been made with the consent of a new standard.

Operators and manufacturers have pushed the development of the ITU-T Recommendation (G.667) that is the first for adaptive chromatic dispersion compensators.

Chromatic dispersion is a phenomenon that produces pulse broadening in optical fibers, and can limit the overall amount of data transported over them.  In some applications, the chromatic dispersion of the optical path varies with time or optical network re-configuration to such an extent that, to avoid signal degradations at the receiver, an adaptive dispersion compensator is used to dynamically compensate the chromatic dispersion change of the optical link.

The automatic management of chromatic dispersion of the optical path, previously not standardized, means that for operators it will be much simpler to change the path of an optical channel in the optical network while maintaining the desired degree of chromatic dispersion. The standard allows for chromatic dispersion compensation to be controlled automatically in real time rather than operators having to manually change physical devices in the network.

The need for chromatic dispersion compensators is increasingly influenced by bit-rate as optical transmission systems are being upgraded from 10 to 40Gbit/s. Distance is also a factor as optical systems – ultra long-haul - now extend to thousands of kilometers. In such situations the accumulation of chromatic dispersion variation with time or temperature of the optical path can exceed tolerance and therefore adaptive compensation is necessary. Network operation costs and flexibility should be favorably impacted by the ability to have chromatic dispersion compensation achieved automatically within the network.