Polarization mode dispersion compensation in optical transmission media

A method of compensating for polarization mode dispersion of a light signal, comprising the steps of:

• providing a sample light signal;
• introducing at least three phase delays between a first polarization component and a second polarization component of the sample light signal;
• providing an interference signal for each of the phase delays by interfering the first and second polarization components;
• measuring the intensity of each of the interference signals;
• and
• compensating for polarization mode dispersion of the light signal based on the measured intensities of the interference signals by:
• determining a polarization mode dispersion vector for the light signal using the measured intensities of the interference signals;
• and
• using the polarization mode dispersion vector to determine a modification to the light signal that substantially compensates for polarization mode dispersion of the light signal.

An apparatus for determining polarization mode dispersion of a light signal, comprising:

• a phase delay generator positioned to receive a sample light signal comprising at least a portion of a light signal and introduce a selectable phase delay value between polarization components of the sample light signal;
• an interferometer in optical communication with the phase delay generator and positioned to interfere polarization components of the sample light signal received from the phase delay generator to produce an interference signal;
• a detector in optical communication with the interferometer and positioned to measure the interference signal;
• and
• a polarization state generator that determines the polarization states of the principal states of polarization of the light signal, the relative amplitudes of the principal states of polarization of the light signal, and the differential group delay between the principal states of polarization based on a plurality of measured interference signals.

An apparatus for compensating for polarization mode dispersion of a light signal, comprising:

• a phase delay generator positioned to receive a sample light signal comprising at least a portion of a light signal in an optical transmission medium;
• a rotator positioned to provide at least two rotational orientations of the polarization axes of the sample light signal with respect to an optical axis of the phase delay generator;
• an interferometer positioned to interfere polarization components of the sample light signal received from the phase delay generator to produce an interference signal;
• a wavelength demultiplexer positioned to spectrally disperse the interference signal into spectrally contiguous subbands;
• an array of detectors, each detector of said array positioned to measure the interference signal of one spectrally contiguous subband;
• a polarization state generator that determines the polarization state of the light signal for each of said spectrally contiguous bands based on a plurality of measured interference signals;
• and
• a compensation stage in optical communication with the optical transmission medium and adapted to compensate for polarization mode dispersion of the light signal in each of said spectrally dispersed channels based on the polarization states of the spectrally contiguous subbands of said spectrally dispersed channels.

A method of compensating for polarization mode dispersion of a light signal in an optical transmission medium, comprising the steps of:

• providing a sample light signal comprising a portion of a light signal in an optical transmission medium;
• introducing a first phase delay between a first polarization component and a second polarization component of the sample light signal and interfering the first and second polarization components to produce a first interference signal;
• measuring the intensity of the first interference signal;
• introducing a second phase delay between the first polarization component and the second polarization component of the sample light signal and interfering the first and second polarization components to produce a second interference signal;
• measuring the intensity of the second interference signal;
• introducing a third phase delay between the first polarization component and the second polarization component of the sample light signal and interfering the first and second polarization components to produce a third interference signal;
• measuring the intensity of the third interference signal;
• providing a rotated sample light signal by rotating polarization axes of the sample light signal;
• introducing a fourth phase delay between a first polarization component and a second polarization component of the rotated sample light signal and interfering the first and second polarization components to produce a fourth interference signal;
• measuring the intensity of the fourth interference signal;
• introducing a fifth phase delay between the first polarization component and the second polarization of the rotated sample light signal and interfering the first and second polarization components to produce a fifth interference signal;
• measuring the intensity of the fifth interference signal;
• introducing a sixth phase delay between the first polarization component and the second polarization of the rotated sample light signal and interfering the first and second polarization components to produce a sixth interference signal;
• measuring the intensity of the sixth interference signal;
• and
• compensating for polarization mode dispersion of the light signal based on the measured intensities of the first, second, third, fourth, fifth and sixth interference signals.