Experimental demonstration of tunable and automatically-locked homodyne detection for dual-polarization 20–32-Gbaud QPSK channels using nonlinear mixing and polarization diversity

We experimentally demonstrate a tunable homodyne receiver on polarization multiplexed QPSK signals. PPLN waveguides inside the polarization diversity loops are used to frequency/phase lock the signals with the LO. Open eye diagrams with BER measurements are shown.