All-optical format conversion from PDM-QPSK to PDM-PAM4 using vector phase-sensitive amplification

In this paper, an all-optical format conversion system from polarization division multiplexed (PDM)-quadrature phase shift keying to PDM-4-level pulse amplitude modulation signal is proposed, analyzed and simulated. The method is based on the vector degenerate phase sensitive amplification (PSA) and non-degenerate PSA in semiconductor optical amplifiers (SOA). The constellations, eye diagrams, error vector magnitudes (EVM) and bit error ratios (BER) are measured to show the system performances.