近日，浙江实验室前沿基础研究中心袁小聪团队报道了高速全光神经网络支持时空模式复用。2025年9月25日，《光：科学与应用》杂志发表了这一成果。

轨道角动量（OAM）光束具有螺旋相位结构和相位奇点的特点，已成为通过模分复用（MDM）实现高容量光通信的有力阻力。传统的仅在空间域中运行的OAM多路复用系统面临着重大挑战，包括增加的系统复杂性、多模态串扰和有限的可扩展性。最近的进展探索了混合复用方案，将OAM与波长或偏振自由度结合起来，展示了Pbit/s级的传输能力。然而，这些系统主要依赖于连续波激光器和外部调制器，这限制了它们在具有挑战性的环境中的适用性，而脉冲激光器提供卓越的峰值功率，增强的传输速率，以及实现OAM激光器的潜力，通常发射脉冲OAM光束。

研究组报告了一种基于OAM的时空复用（OAM-STM）技术，该技术通过衍射深度神经网络（D2NN）和光纤延迟线协同实现脉冲OAM波束，将空间模式信息投射到时域。该方法通过激活未充分利用的时间维度，充分发挥了脉冲激光强度的潜力，从而克服了重复速率瓶颈，提高了信道吞吐量。研究组通过实验证明了一种基于OAM的时空解复用器，如果OAM生成足够快，则可以实现仅受光电二极管带宽限制的解复用速度。同时，该体系结构与高重复速率的OAM结构具有内在的兼容性，使整个系统具有GHz速率的可扩展性。这项工作为高速、全光和高容量OAM-STM系统建立了基础框架，对自由空间光通信、水下通信链路和其他复杂环境具有重要意义。

附：英文原文

Title: High-speed all-optical neural networks empowered spatiotemporal mode multiplexing

Author: Feng, Fu, Li, Xiaolong, Zhang, Ziyang, Gan, Jiaan, Yuan, Xiaocong

Issue&Volume: 2025-09-25

Abstract: Orbital angular momentum (OAM) beams, characterized by a helical phase structure and phase singularity, have emerged as a powerful resource for high-capacity optical communications through mode-division multiplexing (MDM). Traditional OAM multiplexing systems operating solely in the spatial domain face significant challenges, including increased system complexity, inter-modal crosstalk, and limited scalability. Recent advances have explored hybrid multiplexing schemes combining OAM with wavelength or polarization degrees of freedom, demonstrating Pbit/s level transmission capacities. However, these systems predominantly rely on continuous-wave lasers and external modulators, which constrain their applicability in challenging environments, whereas pulsed lasers provide superior peak power, enhanced transmission robustness, and the potential for implementation of OAM lasers, which generally emit pulsed OAM beams. Here, we report an OAM-based spatiotemporal multiplexing (OAM-STM) technique that synergistically implements pulsed OAM beams with a diffractive deep neural network (D2NN) and optical fiber delay lines to project spatial mode information into the temporal domain. This approach leverages the full potential of pulsed laser sources by activating the underutilized time dimension, thereby overcoming the repetition-rate bottleneck and enhancing channel throughput. We experimentally demonstrate an OAM-based spatiotemporal demultiplexer achieving demultiplexing speed limited only by the bandwidth of the photodiode if OAM generation is fast enough. In the meantime, the architecture is intrinsically compatible with high-repetition-rate OAM sources, offering the entire system the scalability to GHz rates. This work establishes a foundational framework for high-speed, all-optical, and high-capacity OAM-STM systems, with promising implications for free-space optical communication, underwater communication links, and other complex environments.

DOI: 10.1038/s41377-025-02007-5

Source: https://www.nature.com/articles/s41377-025-02007-5