Stabilisation of lasers for FDM systems

The author has examined the requirements for an FDM network and the possible schemes for controlling the transmitter lasers. A system based on simple etalons made from commercial fibre connectors forms the basis of the proposed system: these etalons form a passive optical comb onto which each channel can lock. In an experimental system FSK modulated lasers were successfully locked to an etalon passband. The control system was able to tune the lasers up and down to neighbouring etalon modes, under computer control if desired. The addition of a coarse resolution scanning etalon was able to overcome the ambiguity between different etalon modes, leaving the accurate stabilisation problem to the feedback electronics. The system could be used to control a large number of lasers, and is simple enough to be duplicated many times in a network