Conical emission from laser filaments and higher-order Kerr effect in air

TL;DR

This paper numerically studies conical emission from ultrashort laser filaments, examining the impact of higher-order Kerr effects, revealing that HOKE influences CE mainly in tightly focused beams due to nonlinear focusing and modulational instability.

Contribution

It provides new insights into how higher-order Kerr effects affect conical emission, especially in tightly focused laser filaments, which was not thoroughly understood before.

Findings

HOKE has minimal impact on CE in collimated beams.

Differences in CE due to HOKE are significant in tightly focused beams.

The study clarifies the roles of nonlinear focus and modulational instability in CE.

Abstract

We numerically investigate the conical emission (CE) from ultrashort laser filaments, both considering and disregarding the higher-order Kerr effect (HOKE). While the consideration of HOKE has almost no influence on the predicted CE from collimated beams, differences arise for tightly focused beams. This difference is attributed to the different relative contributions of the non-linear focus and of the modulational instability over the whole filament length.