Digital Frequency-Domain MIMO Equalizer Enabling Six-LP-Mode Strong-Coupling IM/DD MDM Optical Transmission System

作者：Jianyu Long, Chen Wang, Ying Wu, Bohan Sang, Chengzhen Bian, Xiongwei Yang, Long Zhang, Yifan Chen, Qinyi Zhang, Ying Wang, Yichen Li, Wen Zhou, Kaihui Wang, Bo Liu, Lei Shen, Jianjun Yu · 发表于：Sensors · 年份：2025 · DOI：10.3390/s25082562 · 被引用次数：5 · 研究领域：Optical Network Technologies、Photonic and Optical Devices、Advanced Photonic Communication Systems

Mode division multiplexing (MDM) techniques provide significant enhancement of the capacity of optical intensity modulation and direct detection (IM/DD) short-reach communication systems, like the datacenter interconnection scenarios. While the introduction of multiple modes leads to mode coupling that will extremely deteriorate the received signals, two approaches have been explored to address this issue: one involves the application of all-link weakly coupled components to suppress modal crosstalk, while the other utilizes optical multiple-input-multiple-output (MIMO) equalizers based on optical devices for signal decoupling. However, pure digital signal processing (DSP)-based schemes for mode decoupling in IM/DD MDM systems with strong mode coupling remain unexplored. In this paper, we propose to use a frequency-domain MIMO equalizer for compensating the modal interference in the strong-coupling linear-polarized (LP) MDM IM/DD system. The signal recovery capability of the proposed method is verified through numerical simulation. Finally, we successfully experimentally demonstrate the transmission of on-off-key (OOK) signals in a six-LP-mode strong-coupling MDM IM/DD system over a 10 km few-mode fiber, employing a pair of strong-coupling mode multiplexers/demultiplexers. The experimental results indicate that, with the frequency-domain MIMO equalizer, OOK signals from all modes can be recovered with an 11% hard-decision forward error correction threshold of 8.3 × 10-3. The ...