Apparatus and method for monitoring change of polarization state resulted from optical link and optical receiver

An apparatus for monitoring a change of a polarization state resulted from an optical link, the apparatus comprising:

• a memory;
• a processor coupled to the memory and configured to:
• extract first equalization coefficients of taps of an equalizer performing equalization on a first signal received at a first moment and second equalization coefficients of the taps of the equalizer performing equalization on a second signal received at a second moment;
• perform summation on the first equalization coefficients of the taps of the equalizer to obtain a first response matrix at a zero frequency, and perform summation on the second equalization coefficients of the taps of the equalizer to obtain a second response matrix at the zero frequency;
• respectively extract phase information on the first signal and the second signal received at the first moment and the second moment to obtain a first transmission matrix of a phase response at the first moment and a second transmission matrix of a phase response at the second moment;
• determine a first channel response matrix according to the first response matrix and the first transmission matrix, and a second channel response matrix according to the second response matrix and the second transmission matrix;
• determine a change matrix of channel response matrices at the first moment and the second moment according to the first channel response matrix and the second channel response matrix;
• and
• determine, according to the change matrix, a parameter characterizing a change of a polarization state resulted from an optical link.