Polarization Division Multiplexing (PDM) has been widely denoted either by polarization multiplexing, polarization division multiplexing, dual polarization or orthogonal polarization. PDM-QPSK is primarily designed for 100 Gbps channel systems.
PDM-QPSK combined with coherent detection (demodulation). In case of coherent demodulation carrier used for demodulation purpose is in phase and frequency synchronism with carrier used for modulation purpose. For non-coherent demodulation it is not in synchronism. Coherent light is a light in which the electromagnetic waves maintain a fixed and predictable phase relationship with each other over a period of time.
Advantages:
Disadvantages and limits:
Transceiver’s construction: