Polarization Dependence of Carrier Extraction from Dual-Polarization Phase-Conjugated Twin Waves with Sum-Frequency Generation in a Pump Phase-Locked Loop for Phase-Sensitive Optical Amplifier Repeaters

This study aimed to build a numerical model of carrier extraction from dual-polarization phase-conjugated twin waves (DP-PCTWs) to investigate polarization dependence on the carrier extraction in a pump phase-locked loop for phase-sensitive optical amplifier repeaters. First, the numerical model was developed, and extracted carrier power of 40-Gbit/s DP-PCTWs with quadrature phase-shift keying format was calculated. Numerical results show the extracted carrier disappears when the PCTWs are circular polarization, and polarization dependence exists on the carrier extraction. Then, carrier extraction of a 10-Gbit/s DP-PCTW with binary phase-shift keying format was experimentally demonstrated. The extracted carrier power was found to be relatively low when the DP-PCTWs are circular polarization, and this trend agrees closely with the numerical results. These results show the reasonability of the numerical model and existence of polarization dependence on the carrier extraction from DP-PCTWs.