A method of polarization demultiplexing for a coherent optical receiver, comprising the steps consisting of: filtering in an adaptive polarization demultiplexing filter a first multiplexed signal and a second multiplexed signal so as to produce a first filtered signal and a second filtered signal, said first multiplexed signal and second multiplexed signal constituting two electrical components obtained by a coherent detection sequence of a polarization-multiplexed optical signal, iteratively determining at least one error parameter based on said first and second filtered signals, and iteratively adjusting the coefficients of said adaptive filter based on said at least one error parameter, said coefficients being associated with samples of said filtered input signals taken at successive clock times, comparing said first and second filtered signals to one another so as to detect a state of degeneration, calculating four central nonzero coefficients associated with a central clock time within said successive clock times based on a selected value of an angle of rotation Θ and a selected value of an ellipticity δ, the four central coefficients forming a rotation matrix cos θ e - j δ sin θ - e j δ sin θ cos θ imposing modified initial filter coefficients on said adaptive filter in response to the detection of said state of degeneration, said modified initial filter coefficients comprising said four central nonzero coefficients iteratively redetermining said at least one error parameter based on said first and second filtered signals, and readjusting said coefficients of said adaptive filter based on said at least one error parameter, selecting successively different angle of rotation values and ellipticity values in response to successive detections of said state of degeneration, in order to calculate said central nonzero coefficient each time. filtering in an adaptive polarization demultiplexing filter a first multiplexed signal and a second multiplexed signal so as to produce a first filtered signal and a second filtered signal, said first multiplexed signal and second multiplexed signal constituting two electrical components obtained by a coherent detection sequence of a polarization-multiplexed optical signal, iteratively determining at least one error parameter based on said first and second filtered signals, and iteratively adjusting the coefficients of said adaptive filter based on said at least one error parameter, said coefficients being associated with samples of said filtered input signals taken at successive clock times, comparing said first and second filtered signals to one another so as to detect a state of degeneration, calculating four central nonzero coefficients associated with a central clock time within said successive clock times based on a selected value of an angle of rotation Θ and a selected value of an ellipticity δ, the four central coefficients forming a rotation matrix cos θ e - j δ sin θ - e j δ sin θ cos θ imposing modified initial filter coefficients on said adaptive filter in response to the detection of said state of degeneration, said modified initial filter coefficients comprising said four central nonzero coefficients iteratively redetermining said at least one error parameter based on said first and second filtered signals, and readjusting said coefficients of said adaptive filter based on said at least one error parameter, selecting successively different angle of rotation values and ellipticity values in response to successive detections of said state of degeneration, in order to calculate said central nonzero coefficient each time.