Controlling attosecond transient absorption with tunable, non-commensurate light fields

We demonstrate a transient absorption scheme that uses a fixed-spectrum attosecond pulse train in conjunction with a tunable probe laser to access a wide range of nonlinear light-atom interactions. We exhibit control over the time-dependent Autler–Townes splitting of the 1s4p absorption line in heli...

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Bibliographic Details
Published in:Optics letters 2018-07, Vol.43 (14)
Main Authors: Harkema, Nathan, Bækhøj, Jens E., Liao, Chen-Ting, Gaarde, Mette B., Schafer, Kenneth J., Sandhu, Arvinder
Format: Article
Language:English
Subjects:
ATOMIC AND MOLECULAR PHYSICS
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Summary:We demonstrate a transient absorption scheme that uses a fixed-spectrum attosecond pulse train in conjunction with a tunable probe laser to access a wide range of nonlinear light-atom interactions. We exhibit control over the time-dependent Autler–Townes splitting of the 1s4p absorption line in helium, and study its evolution from a resonant doublet to a light-induced sideband with changing probe wavelength. The non-commensurate probe also allows for the background-free study of two-infrared-photon emission processes in a collinear geometry. Using this capability, we observe two different emission pathways with non-trivial delay dependencies, one prompt and the other delayed. Here, we identify the nonlinear processes underlying these emissions by comparing the experimental results to calculations based on the time-dependent Schrödinger equation.
ISSN:0146-9592
1539-4794