Filament propagation length of femtosecond pulses with different transverse modes

TL;DR

This study experimentally compares filamentation lengths of femtosecond pulses with different transverse modes in water, revealing that Bessel-Gaussian beams produce longer filaments, influenced by the number of radial lobes.

Contribution

It demonstrates that Bessel-Gaussian beams create longer filaments than Gaussian and Laguerre-Gaussian beams under identical conditions, highlighting the role of radial lobes as energy reservoirs.

Findings

Bessel-Gaussian beams produce longer filaments.

Filament length increases with the number of radial lobes.

Radial lobes act as energy reservoirs for filament formation.

Abstract

We experimentally studied intense femtosecond pulse filamentation and propagation in water for Gaussian, Laguerre-Gaussian, and Bessel-Gaussian incident beams. These different transverse modes for incident laser pulses were created from an initial Gaussian beam by using a computer generated hologram technique. We found that the length of the filament induced by the Bessel-Gaussian incident beam was longer than that for the other transverse modes under the conditions of the same peak intensity, pulse duration, and the size of the central part of the beam. To better understand the Bessel-Gaussian beam propagation, we performed a more detailed study of the filament length as a function of the number of radial modal lobes. The length increased with the number of lobes, implying that the radial modal lobes serve as an energy reservoir for the filament formed by the central intensity peak.