Focusability in the multi-pump laser pulse amplification in plasma

Spatially combining multiple strong laser beams is a promising concept for achieving ultrahigh laser intensities. Proof-of-principle experiments have been conducted at the National Ignition Facility to report a combination of up to twenty pulses with high energy conversion efficiency [1]. However, the combination process could reduce the seed focusability due to the mismatch of the seed and pump wavefronts. Here, we investigate the effect of the finite pump beam size on the focusability of the seed pulse. We propose an approach to retain and even improve the seed focusability by specifically arranging multiple pump beams. The results are demonstrated by numerical solution of coupled nonlinear Schrodinger equations and 2D particle-in-cell simulations.

[1] R.K. Kirkwood et al., Appl. Phys. Lett. 120, 200501 (2022)