2025/01/23 by Yongxin Sun, Hexun Jiang, Yicheng Xu +5
Engineering · #Advanced Photonic Communication Systems #Optical Network Technologies #Photonic and Optical Devices
paper · doi:10.1109/jlt.2025.3533197
openalex publication_date 2025/01/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Coherent optics has shown significant potential as a viable solution for achieving 100 Gb/s and higher speeds in single-wavelength passive optical networks (PON). However, upstream coherent burst-mode detection is a major challenge in deploying coherent optics in access networks. To accelerate digital signal processing (DSP) convergence with minimal preamble length, we propose a novel burst-mode preamble design based on a constant amplitude zero auto-correlation (CAZAC) sequence. This design facilitates comprehensive frequency-domain estimation of various impairments, including state of polarization, chromatic dispersion and differential group delay, providing overall system response information for the equalization pre-convergence. Additionally, this preamble utilizes the same training unit to jointly achieve three key DSP functions: frame synchronization, frequency offset estimation, and channel estimation. This integration contributes to a significant reduction in the preamble length. The feasibility of the proposed preamble with a length of 400 symbols and corresponding DSP was experimentally verified in a 15 Gbaud coherent system using dual-polarization 16 quadrature amplitude modulation. The experimental results based on this scheme showed a superior performance of the convergence acceleration.