Perturbation of V-point polarization singular vector beams

Abstract

The structured beams of light endowed with vector field singularities can be expressed as a superposition of spin and orbital angular momentum states. This article investigates the effect of perturbation of vector field singularities by superposing it with a homogeneously polarized beam and discusses its possible applications in studying the chiroptical effects. This perturbation leads to the splitting of vector field singularities (V-points) into stable lower-index ellipse field singularities (C-points). The strength of perturbation decides the separation between the two C-points in the resultant beam. It is found that the unfolding of V-points into lower-index C-points is always accompanied by a measurable centroid shift in the total and component intensity distribution of the resultant beam. Moreover, the centroid shift is more pronounced in the component intensity, whose state of polarization matches the state of polarization of the perturbing beam. The strength of perturbation can be measured by analyzing the radial shift in the centroid of the beam. It is observed that in the process of perturbation, the polarization singularity index is always conserved while the net helicity in the resultant beam is decided by the helicity of the perturbing beam. The strength of the perturbing beam can be modified by introducing a chiral sample in the beam path which may be useful to investigate the chiroptical effects.