Joint equalization of EEPN, RSOP, and CD with the sliding window assisted extended Kalman filter for a high baud rate Stokes vector direct detection system

Equalization-enhanced phase noise (EEPN) has emerged as one of the major impairments that cannot be ignored for a high baud rate Stokes vector direct detection (SVDD) system. When EEPN interacts with the rotation of state-of-polarization (RSOP) and chromatic dispersion (CD), the joint impairment effects become even more complicated. To achieve the joint equalization of EEPN, RSOP, and CD impairments of a high baud rate SVDD system, this paper first derives a joint impairment model of these three kinds of impairments, and then proposes a joint equalization scheme of EEPN, RSOP, and CD with a sliding window assisted extended Kalman filter (SWA-EKF). The SWA-EKF scheme first tracks RSOP in the time domain, subsequently compensates CD in the frequency domain, and finally performs EEPN mitigation in the time domain again. The effectiveness of the proposed scheme has been verified by a 60 GBaud SVDD-16QAM simulation system. The results show that when these three impair-ments are jointly equalized, the SWA-EKF scheme can track RSOP as fast as 3 Mrad/s, cumulative dispersion up to 1600 ps/nm, and EEPN caused by laser linewidth up to 3 MHz. In addition, with an optical signal-to-noise ratio penalty of 0.3 dB, it could increase 35 G baud rate under 3 MHz laser linewidth for the SVDD system. More importantly, its total complexity can be reduced to an order of O(1Vlog1V). (c) 2023 Optica Publishing Group

Automated summary

This study proposes a joint equalization scheme for a high baud rate Stokes vector direct detection (SVDD) system, which can simultaneously equalize phase noise, rotation of state-of-polarization (RSOP), and chromatic dispersion (CD) impairments. The scheme utilizes a sliding window assisted extended Kalman filter (SWA-EKF) to track RSOP in time domain, compensate for CD in frequency domain, and mitigate EEPN in time domain again. Simulation results demonstrate that the proposed scheme can effectively track RSOP, compensate for up to 1600 ps/nm of CD, and reduce phase noise caused by a laser linewidth of 3 MHz.