Spectral broadening in convex-concave multipass cells.

Area of Science:

• Laser Physics
• Nonlinear Optics
• Ultrafast Lasers

Background:

• Multi-pass spectral broadening is a key technique for amplifying laser pulse energy and peak power.
• Current energy scaling is limited by optical damage, gas ionization, and beam inhomogeneity.

Purpose of the Study:

• To introduce and validate a novel multi-pass convex-concave arrangement for overcoming spectral broadening limitations.
• To demonstrate energy scaling of laser pulses with improved beam quality.

Main Methods:

• Utilized a proof-of-principle experiment with a convex-concave multi-pass setup.
• Employed spectral broadening of ultrashort laser pulses (260 fs, 15-200 µJ).
• Simulated the concept for higher energy pulses (40 mJ, 1.3 ps).

Main Results:

• Achieved spectral broadening and subsequent compression to approximately 50 fs.
• Demonstrated high energy conversion efficiency of 90%.
• Obtained excellent spatio-spectral homogeneity across the beam profile.

Conclusions:

• The novel multi-pass convex-concave arrangement effectively overcomes limitations in energy scaling for spectral broadening.
• The technique shows promise for further scaling to joule-level energies.
• This advancement is crucial for applications requiring high-energy, high-quality ultrashort laser pulses.