Spectral dependence of purely-Kerr driven filamentation in air and argon

TL;DR

This paper uses numerical simulations to demonstrate that higher-order nonlinear indices significantly influence filamentation in air and argon, indicating plasma generation and filamentation are decoupled, which impacts optimal wavelength choices for applications.

Contribution

It reveals the dominant role of higher-order nonlinear indices in filamentation, challenging the assumption that plasma generation is the primary driver.

Findings

Higher-order nonlinear indices dominate focusing and defocusing.

Plasma generation and filamentation are decoupled.

Ultraviolet wavelengths may not be optimal for ionization applications.

Abstract

Based on numerical simulations, we show that higher-order nonlinear indices (up to $n_8$ and $n_{10}$, respectively) of air and argon have a dominant contribution to both focusing and defocusing in the self-guiding of ultrashort laser pulses over most of the spectrum. Plasma generation and filamentation are therefore decoupled. As a consequence, ultraviolet wavelength may not be the optimal wavelengths for applications requiring to maximize ionization.