Open AccessAttosecond chirp effect on the transient absorption spectrum of laser-dressed helium atom
Author(s) -
H. W. Zhao,
Candong Liu,
Yi Zheng,
Zhinan Zhang,
Ruxin Li
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.007707
Subject(s) - attosecond , chirp , physics , ultrafast laser spectroscopy , optics , helium atom , laser , absorption (acoustics) , ultrashort pulse , pulse (music) , atomic physics , absorption spectroscopy , spectrogram , helium , detector , computer science , computer vision
We theoretically investigate the attosecond transient absorption spectrum of helium atom in the presence of an infrared-dressed laser pulse upon scanning their relative delay, with the particular emphasis on the chirp effect of the attosecond pulse. By numerically solving the fully three-dimensional time-dependent Schrödinger equation, we identify the attoscecond chirp can induce the temporal shift of the absorption spectrogram along the delay axis. Additionally, it is found that the extent of the temporal shift is dependent on both the position of the absorption line and the infrared pulse wavelength, which is well confirmed and reproduced by a three-level model. Moreover, we demonstrate that the observed features can be quantitatively explained in terms of the indirect two-photon absorption processes through some virtual states. This effect might provide a way to measure the chirp of attosecond pulse in an all-optical way.