Bourassin-Bouchet C, Couprie M-E
1] Synchrotron SOLEIL, Saint Aubin, BP 34, 91 192 Gif-sur-Yvette, France [2] Laboratoire Charles Fabry, UMR 8501, Institut d'Optique, CNRS, Univ Paris Sud 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex, France.
Synchrotron SOLEIL, Saint Aubin, BP 34, 91 192 Gif-sur-Yvette, France.
Nat Commun. 2015 Mar 6;6:6465. doi: 10.1038/ncomms7465.
Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter.
待测脉冲是完全相干的，也就是说，它可以通过其频谱和光谱相位来完全描述。然而，在实际中合成完全相干的脉冲并不总是可行的，特别是在急需时间计量的新兴超短X射线源领域。在这里，我们展示了频率分辨光学门控（FROG），这是第一种也是最广泛应用的脉冲表征技术之一，如何能够适用于测量部分相干脉冲，甚至低至阿秒时间尺度。无需对实验设备进行修改；只需改变测量的处理方式。为此，我们从其他常规处理部分相干性的物理分支中汲取灵感，例如量子光学和相干衍射成像。这将有重要且直接的应用，比如能够在存在时间抖动的情况下测量X射线自由电子激光脉冲。
