Enhanced high harmonic generation from multiply ionized argon above 500 eV through laser pulse self-compression

Area of Science:

• Attosecond science
• Nonlinear optics
• Atomic, molecular, and optical physics

Background:

• High harmonic generation (HHG) is a key process for producing extreme ultraviolet and X-ray light.
• Extending the cutoff photon energy of HHG is crucial for advanced applications.
• Ionization-induced defocusing and limited laser intensity typically restrict HHG efficiency and spectral reach.

Purpose of the Study:

• To demonstrate high harmonic emission from multiply charged ions for the first time.
• To enhance laser intensity and counteract ionization-induced defocusing within a single waveguide.
• To extend the cutoff photon energy beyond 500 eV using multiply charged ions.

Main Methods:

• Combining laser pulse self-compression and high harmonic generation in a single waveguide.
• Utilizing multiply charged ions (e.g., argon) with high ionization potentials.
• Comparing results with helium under identical laser parameters.

Main Results:

• First demonstration of high harmonic generation from multiply charged ions.
• Achieved cutoff photon energy in argon exceeding 500 eV.
• Observed higher spectral intensity and cutoff energy compared to helium for the same laser input.

Conclusions:

• The combined self-compression and HHG approach effectively enhances laser intensity and mitigates defocusing.
• Multiply charged ions provide a viable pathway for extending HHG to very high photon energies.
• This method opens new possibilities for generating energetic photons from ions with high ionization potentials.