Orbital angular momentum (OAM) beam induced N2 filamentation

We report a comprehensive experimental investigation of N2 filamentation using a femtosecond spatially structured beam carrying orbital angular momentum (OAM) with topological charges of $\ell$ = 1–3. We observed that the filament length increases with OAM topological charges ($\ell$ = 1–3), and the variation in filament width is negligible. We examined the influence of laser power, polarization, and pulse durations on the filament spatial profiles for various topological charges ($\ell$ = 1–3) of OAM beams. We observed that the filament properties are susceptible to the OAM beam parameters, which is attributed to the effect of OAM on the nonlinear filament formation process. In addition, we carried out supercontinuum imaging to study the transfer of OAM topological charges to the supercontinuum. We observed the OAM supercontinuum, and characterization confirms the transfer of OAM to the supercontinuum. Our results reveal the distinct effect of OAM topological charges and the laser operating parameters on the filament length, width, and supercontinuum generation, offering new insights into controlling filamentation processes using structured light. These findings advance our understanding of the nonlinear light–matter interaction with a structured laser beam.