Investigating the reconstruction of attosecond pulses generated by a seeded free-electron laser

Attosecond pulses are essential to the investigation electron dynamics on their natural timescale. In contrast to widely used methods of producing attosecond pulses using high-order harmonic generation, a recent work reports the reproducible generation of highly customizable attosecond waveforms using the seeded free-electron laser FERMI [1]. In this work, the reconstruction of the attosecond pulses was based on the interference of two and three photon processes as understood in the strong field approximation. Here we investigate how well the reconstruction works when taking into account the effect of the atomic potential of the detection atoms. We study the reconstruction using He, Ne, and Ar atoms, and find that atomic effects are most pronounced near the ionization threshold.

[1] Maroju, P. K., Grazioli, C., Di Fraia, M. et al. Nature 578, 386–391 (2020)