Nonlinear mechanisms to Rogue events in the process of interaction between optical filaments

TL;DR

This paper explores nonlinear interactions between optical filaments, specifically energy exchange via four-photon parametric mixing and filament merging through cross-phase modulation, revealing mechanisms behind rogue events in laser filamentation.

Contribution

It introduces a model describing filament interactions through FPPM and CPM, highlighting nonlinear mechanisms leading to rogue events in optical filamentation.

Findings

Energy exchange depends on initial phase difference

Filament merging occurs without initial phase difference

Cross-phase modulation enables filament interaction

Abstract

We investigate two types of nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing $P_{cr}$. In the first case we study energy exchange between filaments. The model describes this process through degenerate four-photon parametric mixing (FPPM) scheme and requests initial phase difference between the waves. When there are no initial phase difference between the pulses, the FPPM process does not work. In this case it is obtained the second type of interaction as merging between two, three or four filaments in a single filament with higher power. It is found that in the second case the interflow between the filaments has potential of interaction due to cross-phase modulation (CPM).