X and Y waves in the spatiotemporal Kerr dynamics of a self-guided light beam

TL;DR

This paper investigates the nonlinear evolution of a monochromatic Townes beam in a self-focusing medium, revealing the formation of giant Y pulses and amplification of super-broad spectrum X waves through analytical and numerical methods.

Contribution

It uncovers the development of Y pulses and their role in amplifying X waves in the spatiotemporal Kerr dynamics, advancing understanding of self-guided light behavior.

Findings

Giant Y pulses form from perturbations of the Townes beam.

Y pulses feature shock fronts on opposite sides.

Y pulses amplify super-broad spectrum X waves.

Abstract

The nonlinear stage of development of the spatiotemporal instability of the monochromatic Townes beam in a medium with self-focusing nonlinearity and normal dispersion is studied by analytical and numerical means. Small perturbations to the self-guided light beam are found to grow into two giant, splitting Y pulses featuring shock fronts on opposite sides. Each shocking pulse amplifies a co-propagating X wave, or dispersion- and diffraction-free linear wave mode of the medium, with super-broad spectrum.