| In this work, we evaluate different approaches of digital signal processing applied after a coherent receiver in order to recover the binary information of an optical signal modulated in Dual-Polarization Quadrature Phase Shift Keying. We explain in details the functioning of a coherent receiver as well as the optical and electrical signals travelling inside. We present the criteria of the two lasers employed for modulation and demodulation, i.e., the signal and local oscillator lasers, as a function of the modulation format and the binary rate. We expose all the required signal processing for information recovery out of a coherent receiver and mention those who will be assessed in this work, along with the reason of their selection. Subsequently, the metric to assess the different methods is introduced. The latter is twofold and consists of the computational complexity and the final bit error rate that each approach yields. The schematics of the test bed follows in parallel with the parameter space of our setup. The computational complexity and the bit error rate of ten different approaches are presented, and an optimal configuration of methods and parameters to use for such modulation and receiver is deduced. |
