FREQUENCY CONTROL TECHNIQUES IN COHERENT MULTICHANNEL LANS

This paper describes frequency control techniques for cold start and channel recognition functions in coherent multichannel local area networks. A Z-cut quartz etalon can be used to stabilize the optical transmitter frequencies. The capture range and the influence of humidity on a Fabry-Perot etalon are discussed, The frequency deviation of the optical transmitter was estimated to be less than +/-1 GHz in the long term. A double AFC loop has been proposed for local LD frequency control. It showed a wide capture range of +/-100 GHz. Coherent FDM receiver switching to the desired channel was demonstrated over a range from 0 to 40 degrees C in an experiment.