Ring-shaped multi-filament array formation in fused silica using center-blocked femtosecond laser pulses

This study investigates the filamentation of femtosecond vortex and Gaussian beams in fused silica by blocking the center of the beam with opaque disks of different diameters. The results show that appropriate blocking leads to energy redistribution, resulting in the formation of a ring-shaped multi-filament array in fused silica. Compared to Gaussian beams, vortex beams produce a ring-shaped filament distribution with enhanced integrity and uniformity when the beam center is blocked. By adjusting the disk diameter, the onset, propagation range, and ring diameter of the multi-filament array can be effectively controlled, enabling stable propagation of organized filaments over distances of approximately 30 mm. This method significantly improves the spatial organization of filament distributions. These findings provide a new approach for organizing laser filamentation, with potential applications in laser micromachining and nonlinear optics.