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arXiv · 1503.02575

Beyond the single-atom response in absorption lineshapes: Probing a dense, laser-dressed helium gas with attosecond pulse trains

Chen-Ting Liao·Arvinder Sandhu·Seth Camp·Kenneth J. Schafer·Mette B. Gaarde
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Abstract

We investigate the absorption line shapes of laser-dressed atoms beyond the single-atom response, by using extreme ultraviolet (XUV) attosecond pulse trains to probe an optically thick helium target under the influence of a strong infrared (IR) field. We study the interplay between the IR-induced phase shift of the microscopic time-dependent dipole moment and the resonant-propagation-induced reshaping of the macroscopic XUV pulse. Our experimental and theoretical results show that as the optical depth increases, this interplay leads initially to a broadening of the IR-modified line shape, and subsequently to the appearance of new, narrow features in the absorption line.

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Chen-Ting Liao, Arvinder Sandhu, Seth Camp, Kenneth J. Schafer, Mette B. Gaarde. 2015-03-09. Beyond the single-atom response in absorption lineshapes: Probing a dense, laser-dressed helium gas with attosecond pulse trains. https://doi.org/10.1103/physrevlett.114.143002

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