PDM-QPSK vector signal generation by MZM-based optical carrier suppression and direct detection

• We experimentally demonstrate PDM-QPSK modulated vector signal generation adopting MZM-based OCS intensity modulation and direct detection.
• The MZM biased at its OCS point is driven by a 6-GHz precoded vector signal, the phase of which is 1/2 of that of the regular QPSK symbol.
• The BER for the generated 2-Gbaud PDM-QPSK modulated vector signal can reach the HD-FEC threshold of 3.8×10−3 after 80-km SMF-28 transmission in the presence of optical dispersion compensation.

We experimentally demonstrate the generation of polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) modulated vector signal adopting Mach–Zehnder-modulator-based (MZM-based) optical-carrier-suppression (OCS) intensity modulation and direct detection. The MZM is driven by a 6-GHz precoded vector signal carrying 2-Gbaud QPSK transmitter data, and biased at its minimum transmission point to realize OCS modulation. The phase of the 6-GHz precoded vector signal is 1/2 of that of the regular QPSK symbol. Only one polarization beam splitter (PBS) is needed to implement optical polarization diversity. The bit-error rate (BER) for the 2-Gbaud PDM-QPSK modulated vector signal can reach the hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10−3 after 80-km single-mode fiber-28 (SMF-28) transmission in the presence of optical dispersion compensation, and 80-km SMF-28 transmission causes no power penalty.