DP-QPSK demodulator

An optoelectronic module comprising:

• a dual-polarization quadrature phase shift keyed (DP-QPSK) demodulator including:
• a first beam displacer;
• a second beam displacer positioned to receive an output from the first beam displacer;
• a third beam displacer positioned to receive an output from the second beam displacer;
• a first half waveplate positioned to receive an output from the third beam displacer;
• a fourth beam displacer positioned to receive an output from the half waveplate;
• a fifth beam displacer positioned to receive an output from the fourth beam displacer;
• a quarter waveplate positioned between the fourth beam displacer and the fifth beam displacer;
• a sixth beam displacer positioned between the first half waveplate and the fourth beam displacer;
• a half waveplate pile positioned between the sixth beam displacer and the fourth beam displacer;
• a seventh beam displacer positioned between the half waveplate pile and the fourth beam displacer;
• and
• a second half waveplate positioned between the seventh beam displacer and the fourth beam displacer;
• a plurality of optical detectors positioned to receive a plurality of optical signals output by the DP-QPSK demodulator and configured to convert the plurality of optical signals to a plurality of electrical signals;
• and
• a digital signal processor electrically coupled to respective outputs of the plurality of optical detectors.