Role of multiple filaments in self-accelerating actions of laser filamentation in air

The nonlinear dynamics of multiple filaments in self-accelerating actions by using corrected accelerating parabolic beams (CAPBs) are numerically investigated. By increasing the number of main lobes, the curved filaments can be elongated, leading to a longer displacement. The replenished energy originating from curved multiple filaments (MFs) that constructively interfere with the central one plays a crucial role in the phenomenon. At the bifurcation position, a beam pattern in which secondary lobes tightly follow the main lobes is formed, which is beneficial for the accelerating action of MFs. A new curved filament is generated due to the merging of side-curved MFs, and its accelerating strength decreases gradually with further propagation. Moreover, a special spatiotemporal profile that enhances the possibility of acceleration is also formed. The use of the accelerating beam with the appropriate amount of main lobes provides a new approach to elongate curved filaments. (C) 2017 Published by Elsevier B.V.