Efficient preamble design and digital signal processing in upstream burst-mode detection of 100G TDM coherent-PON

Abstract

Coherent optics has been proved to be a promising candidate for 100 Gb/s and even beyond single-wavelength time-division multiplexing passive optical networks (TDM-PONs). However, one of the key issues in TDM coherent-PON is how to efficiently and robustly achieve upstream burst-mode coherent detection. To solve this problem, we proposed and demonstrated a reliable and efficient preamble design with corresponding burst-mode digital signal processing (DSP) for coherent upstream burst-mode detection in TDM coherent-PON. To reduce the preamble length, a special designed preamble unit is used for three burst-mode DSP functions including frame synchronization, state-of-the polarization estimation, and frequency-offset estimation. The efficiency of the designed preamble and the overall performances under different test conditions are experimentally verified. We also confirmed the robust performance in large frequency offset, residual fiber dispersion, and long-time running. As a proof-of-concept, we demonstrate the coherent upstream burst-mode detection of 100-Gb/s polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) signals based on a 71.68-ns preamble and corresponding burst-mode DSP, achieving a 36-dB power budget after 50-km single-mode fiber transmission. Around 20-dB dynamic range of received power is also experimentally verified for burst signals in the ${100\\,\\,\\text{Gb/s/}}\\lambda$100Gb/s/λ TDM coherent-PON.