Patent ID: 6911645

Claim:
An optical channel detector, comprising: (a) an interferometer connected to receive an input optical signal having one or more optical channel signals and generate one or more output optical signals, wherein each output optical signals corresponds to a sum of the input optical signal and a delayed version of the input optical signal; (b) at least one spectrum analyzer connected to receive at least one output optical signal from the interferometer and generate data signals corresponding to the power of the at least one output optical signal at a plurality of different grid frequencies; and (c) a control processor connected to receive the data signals from the at least one spectrum analyzer and generate a control signal to control the delay applied by the interferometer, wherein: the control processor is adapted to control the delay applied by the interferometer at one or more different settings corresponding to different degrees of constructive/destructive interference of the one or more optical channel signals at the different grid frequencies; and the control processor is adapted to compare the data signals generated by the at least one spectrum analyzer for one or more different delay settings to determine whether an optical channel signal is present in the input optical signal at each grid frequency.