Parabolic trajectory of femtosecond laser filaments generated by accelerating parabolic beams in air

Abstract

Nonlinear dynamics of femtosecond filamentation with accelerating parabolic beams are numerically investigated for the first time. The parabolic trajectory of filaments can be formed in the main lobes. For a zero-order accelerating parabolic beam which contains one wing of sidelobes, the accelerating characteristics of filaments are similar to that of the Airy beam. When it comes to the first-order accelerating parabolic beam which consists of two wings of sidelobes with a certain angle between each other, the accelerating action takes place after two main lobes blend together and it can be more obvious with the increase of initial peak intensity. Multiple filaments (MFs) which are formed in the first-order accelerating parabolic beam can benefit the accelerating action of filaments and enhance the length of the parabolic trajectory. In addition, MFs also raise the possibility for pulse splitting of the main lobe in the temporal domain.