Adjustment scheme for a polarization demultiplexer in an optical dual-polarization BPSK receiver

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 (z1) and a second output signal component (z2). The method adjusts the polarization demultiplexer (1-4) based on an error function associated to the first output signal component (z1) and/or an error function associated to the second output signal component (z2). Such an error function associated to an output signal component (z1, z2) comprises a constant modulus error contribution indicating a deviation of the respective output signal component (z1, z2) 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 (z1, z2) comprises a constellation error contribution indicating a deviation of the constellation of the respective output signal component (z1, z2) from a binary constellation, i.e. a constellation error contribution penalizing the deviation of the recovered constellation from a binary constellation.