"Table-top extreme ultraviolet second harmonic generation"

Tobias Helk: Emma Berger, Sasawat Jamnuch, Lars Hoffmann, Adeline Kabacinski, Julien Gautier, Fabien Tissandier, Jean-Philipe Goddet, Hung-Tzu Chang, Juwon Oh, C. Das Pemmaraju, Tod A. Pascal, Stephane Sebban, Christian Spielmann, Michael Zuerch; Science Advances, 05/19/21.

Additional Authors: Emma Berger, Sasawat Jamnuch, Lars Hoffmann, Adeline Kabacinski, Julien Gautier, Fabien Tissandier, Jean-Philipe Goddet, Hung-Tzu Chang, Juwon Oh, C. Das Pemmaraju, Tod A. Pascal, Stephane Sebban, Christian Spielmann, Michael Zuerch

Abstract:

The lack of available table-top extreme ultraviolet (XUV) sources with high enough fluxes and coherence properties has limited the availability of nonlinear XUV and x-ray spectroscopies to free-electron lasers (FELs). Here, we demonstrate second harmonic generation (SHG) on a table-top XUV source by observing SHG near the Ti M2,3 edge with a high-harmonic seeded soft x-ray laser. Furthermore, this experiment represents the first SHG experiment in the XUV. First-principles electronic structure calculations suggest the surface specificity and separate the observed signal into its resonant and nonresonant contributions. The realization of XUV-SHG on a table-top source opens up more accessible opportunities for the study of element-specific dynamics in multicomponent systems where surface, interfacial, and bulk-phase asymmetries play a driving role.