Patent ID: 6901225

Claim:
A device for detecting polarization mode dispersion of an optical signal in a receiver, wherein the receiver includes a polarization mode dispersion compensator and a photo detector connected in series for demodulating the optical signal into an electrical signal, the device comprising: a first filter connected to an output of the photo detector; at least one further filter connected to the output of the photo detector, the at least one further filter being a band-pass filter and having a center frequency which is higher than one of a center frequency of the first filter if the first filter is a band-pass filter and a cut-off frequency of the first filter if the first filter is a low-pass filter; a first power detector connected to an output of the first filter for producing a first output voltage as a function of a differential group delay of the optical signal; and at least one further powered detector connected to an output of the at least one further filter for producing at least one further output voltage as a function of the differential group delay of the optical signal; wherein only monotony ranges of the first output voltage and the at least one further output voltage, which lie in a range of the differential group delay between 0 and a change of operational sign of a slope of the respective first output voltage and the at least one further output voltage, are employed for controlling the polarization mode dispersion compensator.