Joint modulation format identification and OSNR monitoring based on Stokes vector distribution features for digital coherent optical receivers

For joint modulation format identification (MFI) and optical signal-to-noise ratio (OSNR) monitoring, a simple and intelligent optical communication performance monitoring method is proposed, and the feasibility is demonstrated by digital coherent optical communication experiments.The experiment results show that for all modulation formats, including 28 GBaud polarization division multiplexing (PDM) QPSK/8-QAM/16-QAM/64-QAM, 100% MFI accuracies are achieved even at OSNR values lower than the corresponding theoretical 20% forward error correction limit, as well as the high accuracies for OSNR monitoring.Furthermore, the proposed scheme has a reasonable monitoring level when chromatic dispersion and fiber nonlinear effects are varied.