The Optimization Scheme Based on Kalman Filter for Self-Homodyne Coherent Detection System Under Fast RSOP

Self-homodyne coherent detection, which meets the transmission requirements of short-reach communication scenarios such as data center interconnects, is limited by carrier fading in the local oscillator (LO) branch and high-power consumption in the digital signal processing (DSP) unit. To address the aforementioned challenges, a comprehensive optimization mechanism is proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> A polarization control method based on Kalman filter is proposed to address the carrier fading issue; A modulation-format-independent, one-step compensation scheme for polarization demultiplexing and carrier phase recovery based on extended Kalman filter is proposed to mitigate the issue of high-power consumption in DSP. To the best of our knowledge, it is the first time using the Kalman filter for polarization control in the optical domain. The effectiveness of the proposed comprehensive optimization mechanism is validated under both linear and random polarization drift models. The results demonstrate that the proposed polarization control method offers advantages in stabilization performance, convergence speed, and adaptivity. Under the constraint of the adaptive polarization controller, the proposed scheme ensures that the system's bit error rate remains below the forward error correction threshold after 10km of fiber transmission, even with a rotation of the state of polarization (RSOP) of 100 krad/s. Furthermore, the proposed Joint-extended Kalman filter (J-EKF) scheme demonstrates lower power consumption and enhanced tolerance to broad linewidth lasers.