In recent years, femtosecond extreme-ultraviolet (XUV) and x-ray pulses from free-electron lasers have developed into important probes to monitor processes and dynamics in matter on femtosecond-time and angstrom-length scales. With the rapid progress of versatile ultrafast x-ray spectroscopy techniques and more sophisticated data analysis tools, accurate single-pulse information on the arrival time, duration, and shape of the probing x-ray and XUV pulses becomes essential. Here, we demonstrate that XUV pulses can be converted into terahertz electromagnetic pulses using a spintronic terahertz emitter. We observe that the duration, arrival time, and energy of each individual XUV pulse is encoded in the waveform of the associated terahertz pulses, and thus can be readily deduced from single-shot terahertz time-domain detection.

中文翻译：

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飞秒极紫外光脉冲的太赫兹波解码

近年来，来自自由电子激光器的飞秒极紫外 (XUV) 和 X 射线脉冲已发展成为重要的探测器，用于在飞秒时间和埃长度尺度上监测物质的过程和动力学。随着多功能超快 X 射线光谱技术和更复杂的数据分析工具的快速发展，关于探测 X 射线和 XUV 脉冲的到达时间、持续时间和形状的准确单脉冲信息变得至关重要。在这里，我们证明了可以使用自旋电子太赫兹发射器将 XUV 脉冲转换为太赫兹电磁脉冲。我们观察到每个单独的 XUV 脉冲的持续时间、到达时间和能量都被编码在相关太赫兹脉冲的波形中，因此可以很容易地从单次太赫兹时域检测中推断出来。