Frequency-resolved optical gating for the complete reconstruction of attosecond bursts (FROG-CRAB) is a well-known technique for the complete temporal characterization of ultrashort extreme ultraviolet (XUV) pulses, with durations down to a few tens of attoseconds. Recently, this technique was extended to few-femtosecond XUV pulses, produced by high-order harmonic generation (HHG) in gases, thanks to the implementation of a robust iterative algorithm: the extended ptychographic iterative engine (ePIE). We demonstrate, by using numerical simulations, that the ptychographic reconstruction technique is characterized by an excellent degree of convergence and robustness. We analyse the effects on pulse reconstruction of various experimental imperfections, namely, the jitter of the relative temporal delay between the XUV pulse and a suitably delayed infrared (IR) pulse and the noise of the measured FROG-CRAB spectrograms. We also show that the ePIE approach is particularly suitable for the reconstruction of incomplete FROG-CRAB spectrograms (i.e., spectrograms with a reduced number of measured time delays) and of spectrograms acquired with a reduced spectral resolution, particularly when relatively high-intensity IR pulses are employed.

中文翻译：

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ePIE算法的鲁棒性可完全表征飞秒，极端紫外线脉冲

用于完全重建阿秒脉冲的频率分辨光学选通（FROG-CRAB）是一种众所周知的技术，用于对持续时间长达数十阿秒的超短极紫外（XUV）脉冲进行完整的时间表征。最近，由于实施了强大的迭代算法：扩展的谱图迭代引擎（ePIE），该技术已扩展到气体中高阶谐波生成（HHG）产生的几飞秒XUV脉冲。通过使用数值模拟，我们证明了谱图重建技术的特点是具有出色的收敛性和鲁棒性。我们分析了各种实验缺陷对脉冲重建的影响，即 XUV脉冲和适当延迟的红外（IR）脉冲之间的相对时间延迟的抖动以及测得的FROG-CRAB频谱图的噪声。我们还表明，ePIE方法特别适用于重建不完整的FROG-CRAB频谱图（即，测量的时延数量减少的频谱图）和具有降低的频谱分辨率的频谱图，特别是在相对高强度的IR脉冲时被雇用。