Abstract

Wavelength division multiplexing is established as an important technique for employing the large bandwidth of optical fibre. There exists a need for a simple wavelength identification scheme to allow recognition of individual wavelengths in the network. One technique which has been proposed is the use of low-frequency pilot tones [1]. In this scheme, each wavelength channel is coded by a different tone frequency. To allow wavelength identification at any point in the network, a small proportion of the optical power in a fibre may be simply be tapped off and detected by a photodiode. The pilot tones can then be filtered electrically and their frequencies and levels registered. If wavelength conversion is also required in the network, the pilot tone for that signal must be removed and replaced with a new one representing the translated wavelength. Here we demonstrate, for the first time we believe, a novel technique for all-optically wavelength converting and simultaneously monitoring and replacing a pilot tone using a single integrated device at 2.488Gb/s.

© 1998 IEEE