Chen Jun, Itakura Ryuji, Nakajima Takashi
Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Opt Express. 2010 Feb 1;18(3):2020-35. doi: 10.1364/OE.18.002020.
We propose a simple scheme to characterize attosecond extreme ultraviolet (XUV) pulses. A broadband ultraviolet (UV) approximately vacuum ultraviolet (VUV) pump pulse creates a coherent superposition of atomic bound states, from which photoionization takes place by the time-delayed attosecond XUV probe pulse. Information on the spectral phase of the XUV pulse can be extracted from the phase offset of the interference beating in the photoelectron spectra using a standard SPIDER (spectral phase interferometry for direct electric-field reconstruction) algorithm. We further discuss the influence of the chirp and polychromaticity of the pump pulse, and show that they do not spoil the reconstruction process. Since our scheme is applicable for various simple atoms such as H, He, and Cs, etc., and capable of characterizing attosecond XUV pulses with a pulse duration of a few hundred attoseconds or even less, it can be an alternative technique to characterize attosecond XUV pulses. Specific numerical examples are presented for the H atom utilizing the 2p and 3p states.
我们提出了一种简单的方案来表征阿秒极紫外（XUV）脉冲。一个宽带紫外（UV）近似真空紫外（VUV）泵浦脉冲产生原子束缚态的相干叠加，延时的阿秒XUV探测脉冲从该叠加态引发光电离。利用标准的SPIDER（用于直接电场重建的光谱相位干涉测量法）算法，可从光电子能谱中的干涉拍频的相位偏移提取XUV脉冲光谱相位的信息。我们进一步讨论了泵浦脉冲的啁啾和多色性的影响，并表明它们不会破坏重建过程。由于我们的方案适用于各种简单原子，如H、He和Cs等，并且能够表征脉冲持续时间为几百阿秒甚至更短的阿秒XUV脉冲，它可以作为表征阿秒XUV脉冲的一种替代技术。利用H原子的2p和3p态给出了具体的数值示例。
