Characterizing ultrashort optical pulses has always been a critical but difficult task, which has a broad range of applications. We propose and demonstrate a self-referenced method of characterizing ultrafast pulses with a multimode fiber. The linear and nonlinear speckle patterns formed at the distal end of a multimode fiber are used to recover the spectral amplitude and phase of an unknown pulse. We deploy a deep learning algorithm for phase recovery. The diversity of spatial and spectral modes in a multimode fiber removes any ambiguity in the sign of the recovered spectral phase. Our technique allows for single-shot pulse characterization in a simple experimental setup. This work reveals the potential of multimode fibers as a versatile and multi-functional platform for optical sensing.

中文翻译：

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使用多模光纤深度学习超快脉冲

表征超短光脉冲一直是关键但困难的任务，其具有广泛的应用范围。我们提出并演示了一种使用多模光纤表征超快脉冲的自参考方法。在多模光纤的远端形成的线性和非线性斑点图案用于恢复未知脉冲的光谱幅度和相位。我们部署了深度学习算法来进行相恢复。多模光纤中空间模式和光谱模式的多样性消除了恢复光谱相位符号的任何歧义。我们的技术允许在简单的实验装置中进行单次脉冲表征。这项工作揭示了多模光纤作为光学感测的多功能平台的潜力。