Pushing DSP-Free Coherent Interconnect to the Last Inch by Optically Analog Signal Processing

Mingming Zhang; Haoze Du; Xuefeng Wang; Junda Chen; Weihao Li; Zihe Hu; Yizhao Chen; Can Zhao; Hao Wu; Jiajun Zhou; Siyang Liu; Siqi Yan; Ming Tang

arXiv · 2503.11618

Pushing DSP-Free Coherent Interconnect to the Last Inch by Optically Analog Signal Processing

Mingming Zhang·Haoze Du·Xuefeng Wang·Junda Chen·Weihao Li·Zihe Hu·Yizhao Chen·Can Zhao·Hao Wu·Jiajun Zhou·Siyang Liu·Siqi Yan·Ming Tang

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Abstract

To support the boosting interconnect capacity of the AI-related data centers, novel techniques enabled high-speed and low-cost optics are continuously emerging. When the baud rate approaches 200 GBaud per lane, the bottle-neck of traditional intensity modulation direct detection (IM-DD) architectures becomes increasingly evident. The simplified coherent solutions are widely discussed and considered as one of the most promising candidates. In this paper, a novel coherent architecture based on self-homodyne coherent detection and optically analog signal processing (OASP) is demonstrated. Proved by experiment, the first DSP-free baud-rate sampled 64-GBaud QPSK/16-QAM receptions are achieved, with BERs of 1e-6 and 2e-2, respectively. Even with 1-km fiber link propagation, the BER for QPSK reception remains at 3.6e-6. When an ultra-simple 1-sps SISO filter is utilized, the performance degradation of the proposed scheme is less than 1 dB compared to legacy DSP-based coherent reception. The proposed results pave the way for the ultra-high-speed coherent optical interconnections, offering high power and cost efficiency.

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Mingming Zhang, Haoze Du, Xuefeng Wang, Junda Chen, Weihao Li, Zihe Hu, Yizhao Chen, Can Zhao, Hao Wu, Jiajun Zhou, Siyang Liu, Siqi Yan, Ming Tang. 2025-03-14. Pushing DSP-Free Coherent Interconnect to the Last Inch by Optically Analog Signal Processing. https://arxiv.org/abs/2503.11618

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