Modeling the Impact of Equalization-Enhanced Phase Noise on DSP in Optical Coherent Receivers

Equalization-enhanced phase noise (EEPN) represents one of the major challenges toward the development of next generation coherent optical systems operating at high data rates. Therefore, a deep understanding of this phenomenon is fundamental to design efficient mitigation solutions in digital signal processing (DSP). This paper provides an in-depth analysis of the main impairments caused by EEPN, namely, timing jitter, phase noise and additional interferent. Based on analytical formulation, the standard deviation and bandwidth of the timing jitter are derived as well as its distortion contribution in terms of equivalent signal-to-noise ratio (SNR). The phase noise before the carrier phase recovery (CPR) and the SNR contribution due to the interferent component of EEPN are also derived. Simulation results confirm our theoretical predictions. The knowledge of these quantities sets the requirements for the optimal design of timing recovery (TR) and CPR in digital coherent receiver in presence of EEPN impairments.