Focusability in the multi-pump Raman amplification of short laser pulses

TL;DR

This paper investigates how the finite size of pump beams affects seed pulse focusability in multi-pump Raman amplification and proposes a method to improve focusability through specific pump beam arrangements, supported by numerical simulations.

Contribution

It introduces a novel approach to arrange multiple pump beams to preserve and enhance seed focusability in multi-pump Raman amplification.

Findings

Finite pump beam size impacts seed focusability.

Specific pump arrangements can improve focusability.

Numerical simulations validate the proposed method.

Abstract

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. However, the combination process might damage the seed focusability due to 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 Schr\"{o}dinger equations.