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

Nathan Harkema, Jens E. Bækhøj, Chen Ting Liao, Mette B. Gaarde, Kenneth J. Schafer, Arvinder Sandhu

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


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. We identify the nonlinear processes underlying these emissions by comparing the experimental results to calculations based on the time-dependent Schrödinger equation.

Original languageEnglish (US)
Pages (from-to)3357-3360
Number of pages4
JournalOptics letters
Issue number14
StatePublished - Jul 15 2018

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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