Demonstration of tunable and automatic frequency/phase locking for multiple-wavelength QPSK and 16-QAM homodyne receivers using a single nonlinear element

We experimentally demonstrate a tunable homodyne receiver on multiple-wavelength QPSK and 16-QAM channels at 20/30 Gbaud. A single PPLN waveguide is used to frequency/phase lock the signals with their tones. Open eye diagrams with BER measurements are shown.