Analysis of signed chromatic dispersion monitoring by waveform asymmetry for differentially-coherent phase-modulated systems

We analytically study received waveform asymmetries induced by chromatic dispersion (CD) for signed CD monitoring in differential quadrature phase-shift keying (DQPSK) systems and show that the asymmetries are results of differential detection and the ±π/4 phase shifters used in conventional DQPSK receivers. The theoretical insights developed help explain various published results on signed CD monitoring based on waveform asymmetries and allow us to further propose signed CD monitoring for differential eight phase-shift keying (D8PSK) systems without any modification to the receiver. Simulation results also show that the CD-induced waveform asymmetric features are preserved in presence of self-phase modulation (SPM) and polarization-mode dispersion (PMD).