Evolution of phase singularities of higher-order Bessel-Gaussian pulsed beams

The analytical expressions of the field and intensity distributions of higher-order Bessel-Gaussian pulsed beams diffracted by an aperture have been derived, which enables us to study the evolution of the phase singularities of the diffracted higher-order Bessel-Gaussian pulsed beams. It is shown that there always exists an optical vortex at the center of the beams and the topological charge is conserved. The phase contours rotate anti clockwise about the z-axis with the increasing pulse frequency and duration. The size of the vortex core decreases with the increasing pulse frequency, but is almost unaffected by pulse duration. The phase contours rotate anti clockwise and clockwise about the z-axis with the increasing truncation parameter and propagation distance respectively. The size of