Power regulation in optical networks

DETAILED DESCRIPTION The invention is a circuit for controlling optical power levels.
The circuit includes at least one electrically controllable optical attenuator having an input for receiving an optical input signal, at least one electrode, and an output for delivering an output signal wherein the output signal power level is normally dependent upon the polarization of the input signal.
The circuit further includes a feedback loop comprising a photodetector optically coupled to at least a portion of the output signal and electrically coupled to the electrode of the attenuator for controlling the power level of the output signal in response to the electrical signal from the photodetector.
The feedback loop results in the power level of the output signal being essentially independent of changes in polarization of the input signal.