| 摘要 |
The invention relates to a method for adjusting a polarization demultiplexer (1-4) in an optical receiver configured to receive a DP-BPSK signal having two BPSK modulated signal components in different polarizations. The polarization demultiplexer (1-4) outputs a first output signal component (z 1 ) and a second output signal component (z 2 ). The method adjusts the polarization demultiplexer (1-4) based on an error function associated to the first output signal component (z 1 ) and/or an error function associated to the second output signal component (z 2 ). Such an error function associated to an output signal component (z 1 , z 2 ) comprises a constant modulus error contribution indicating a deviation of the respective output signal component (z 1 , z 2 ) from a circle around the root of the complex plane. In addition to the constant modulus error contribution, such an error function associated to an output signal component (z 1 , z 2 ) comprises a constellation error contribution indicating a deviation of the constellation of the respective output signal component (z 1 , z 2 ) from a binary constellation, i.e. a constellation error contribution penalizing the deviation of the recovered constellation from a binary constellation.
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