Higher-order Kerr terms allow ionization-free filamentation in gases

TL;DR

This paper demonstrates that higher-order Kerr nonlinearities, rather than plasma generation, are the primary defocusing mechanism enabling filamentation of ultrashort laser pulses in gases, aligning with experimental observations.

Contribution

It introduces the role of higher-order Kerr terms as the main defocusing mechanism in laser filamentation, challenging the traditional plasma-based explanation.

Findings

Higher-order Kerr terms dominate self-channeling in gases.

Experimental intensities and plasma densities are accurately reproduced.

Plasma is not the primary defocusing agent in filamentation.

Abstract

We show that higher-order nonlinear indices ($n_4$, $n_6$, $n_8$, $n_{10}$) provide the main defocusing contribution to self-channeling of ultrashort laser pulses in air and Argon at 800 nm, in contrast with the previously accepted mechanism of filamentation where plasma was considered as the dominant defocusing process. Their consideration allows to reproduce experimentally observed intensities and plasma densities in self-guided filaments.