Patent ID: 8254787

Claim:
A method of generating a feedback signal for polarization mode dispersion (PMD) compensation of an optical Alternate-Polarization Differential-Phase-Shift-Keying (APol-DPSK) signal comprising: demodulating the APol-DPSK signal with a delay-line-interferometer (DLI), the DLI having a free spectral range (FSR) that is different than a symbol rate of the APol-DPSK signal; detecting the demodulated APol-DPSK signal to generate a corresponding electrical signal; bandpass filtering the corresponding electrical signal, the bandpass filtering having a passband including half the symbol rate of the corresponding electrical signal; generating a PMD compensation feedback signal based on a power of the filtered corresponding electrical signal, whereby the power of the filtered corresponding electrical signal is indicative of the PMD in the APol-DPSK signal.