Phase-Matching for Generation of Isolated Attosecond XUV and Soft-X-Ray Pulses with Few-Cycle Drivers

Isolated attosecond pulses (IAPs) produced through laser-driven high-harmonic generation (HHG) hold promise for unprecedented insight into physical, chemical, and biological processes via attosecond x-ray diffraction and spectroscopy with tabletop sources. Efficient scaling of HHG towards x-ray ener...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. X 2020-10, Vol.10 (4), p.041011, Article 041011
Main Authors: Schötz, J., Förg, B., Schweinberger, W., Liontos, I., Masood, H. A., Kamal, A. M., Jakubeit, C., Kling, N. G., Paasch-Colberg, T., Biswas, S., Högner, M., Pupeza, I., Alharbi, M., Azzeer, A. M., Kling, M. F.
Format: Article
Language:English
Subjects:
Argon
Attosecond pulses
Biological activity
Dipoles
Gases
Harmonic generations
Harmonic radiation
Ionization
Lasers
Neon
Phase change
Phase matching
Plasma
Radiation
Scaling
Soft x rays
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Isolated attosecond pulses (IAPs) produced through laser-driven high-harmonic generation (HHG) hold promise for unprecedented insight into physical, chemical, and biological processes via attosecond x-ray diffraction and spectroscopy with tabletop sources. Efficient scaling of HHG towards x-ray energies, however, has been hampered by ionization-induced plasma generation impeding the coherent buildup of high-harmonic radiation. Recently, it has been shown that these limitations can be overcome in the so-called “overdriven regime” where ionization loss and plasma dispersion strongly modify the driving laser pulse over small distances, albeit without demonstrating IAPs. Here, we report on experiments contrasting the generation of IAPs at 80 eV in argon with neon via attosecond streaking measurements. Comparing our experimental results to numerical simulations, we conclude that IAPs in argon are generated in the overdriven regime. We introduce a simple expression that fully describes the HHG dipole phase-mismatch contribution, specifically the effect of the blueshift of the driving laser. Furthermore, we present a method to numerically calculate the transient HHG phase mismatch, which allows us to demonstrate the accuracy of the introduced phase-mismatch expression. Finally, we perform simulations for different gases and wavelengths and show that including the full HHG dipole phase-mismatch contribution is important for understanding HHG with long-wavelength, few-cycle laser pulses in high-pressure gas targets, which are currently being employed for scaling isolated attosecond pulse generation beyond extreme ultraviolet (XUV) towards soft-x-ray photon energies.
ISSN:2160-3308
2160-3308
DOI:10.1103/PhysRevX.10.041011