Cisco Technology, Inc.

Alain Houle

Grant E Moulton

Highly efficient control of laser frequency is provided. An optical channel monitor is coupled to a composite WDM signal resulting from the multiplexing of outputs from multiple laser sources. The monitor determines the frequency of each laser and this measurement is used to provide feedback for laser frequency control. In this way a single optical channel monitor can provide frequency control for numerous WDM channels, greatly reducing the cost and space required. Monitoring capability may be provided to individual channels as needed.

DWDM laser frequency control

A dithering signal is superimposed on a laser frequency control signal. In this way, laser frequency control may be achieved by employing measurements from a single photodetector. By sampling synchronously to the dithering signal, it is possible to generate both the magnitude end sign of the current frequency error based on the output of a single photodetector. This reduces the number of components required to generate an optical signal and is particularly advantageous in WDM systems where laser frequency control components may be duplicated over a large number of channels.

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Petaluma, CA, United States of America

Alain Houle