On the importance of frequency-dependent beam parameters for vacuum acceleration with few-cycle radially-polarized laser beams

TL;DR

This paper demonstrates through simulations that accounting for frequency-dependent beam parameters is crucial for effective vacuum particle acceleration using few-cycle radially-polarized laser beams, affecting energy outcomes significantly.

Contribution

It highlights the importance of considering frequency-dependent parameters in modeling ultrashort radially-polarized laser beams for vacuum acceleration, a factor often overlooked in prior work.

Findings

Proper frequency-dependent modeling significantly alters electron energy outcomes.

Different spatio-spectral profiles can drastically increase or decrease acceleration efficiency.

Accurate characterization of broadband beams is essential for optimization in vacuum acceleration.

Abstract

Tightly-focused, ultrashort radially-polarized laser beams have a large longitudinal field, which provides a strong motivation for direct particle acceleration and manipulation in vacuum. The broadband nature of these beams means that chromatic properties of propagation and focusing are important to consider. We show via single particle simulations that using the correct frequency-dependent beam parameters is imperative, especially as the pulse duration decreases to the few-cycle regime. The results with different spatio-spectral amplitude profiles show both a drastic increase or decrease of the final accelerated electron energy depending on the shape, motivating both proper characterization and potentially a route to optimization.