Patent ID: 8099000

Claim:
A differential delay detection system, comprising: a cross-polarization interferometer which receives a polarization multiplexed input signal and is configured to separately generate polarization independent outputs using split paths and to generate cross-polarization interference outputs; balanced photodetectors which filter the outputs of the cross-polarization interferometer; a training signal receiver which receives the input signal and which is configured to extract a training signal from the input signal and generate updated coefficients representing a rotation of the input's polarization; and a polarization demultiplexer configured to combine the polarization independent outputs and the cross-polarization interference outputs from the cross-polarization interferometer, after they have been filtered by the balanced photodetectors, with the updated coefficients received from the training signal receiver to extract an original, unrotated signal; wherein the cross-polarization interferometer includes a polarization beam splitter to split an incoming optical signal into a first polarization signal and a second polarization signal; wherein the first and second polarization signal are further split and the cross-polarization interferometer further comprises a polarization controller configured to rotate a split version of the first polarization signal by 90 degrees to form a rotated version of the first polarization signal; and wherein a split version of the second polarization signal and the rotated version are cross-coupled with one tap delays to output the cross-polarization interference outputs.