Filamentation characteristics in the transition from cylindrical vector to circularly polarized vortex femtosecond pulses

Abstract

This study investigates the influence of polarization on the filamentation characteristics of femtosecond vector and vortex laser pulses. By using a quarter-wave plate (QWP) and a q-plate to vary the polarization distribution of femtosecond laser beam, we transform the beam from a cylindrical vector to a circularly polarized vortex beam. This transition enables precise control over key parameters, including the on-axis maximum intensity and spectral broadening of the generated supercontinuum. As the QWP angle increases from 0° to 45°, we observe a decrease in both the maximum filamentation intensity and spectral broadening. These parameters exhibit periodic variations as the QWP angle is further increased beyond 45°. Furthermore, circularly polarized vortex beams exhibit delayed filamentation onset, shorter filament length, and lower intensity compared to the linearly polarized beams. These findings highlight the critical role of polarization in modulating filamentation dynamics, offering the way for enhanced applications in air lasing, waveguides, and supercontinuum generation.