Helico-conical vector beams

In this work, we propose and demonstrate experimentally a new family of vector beams, the helico-conical vector beams (HCVBs), whose spatial degree of freedom is encoded in the helico-conical optical beams. We use Stokes polarimetry to study their properties and find that upon propagation their transverse polarization distribution evolves from nonhomogeneous to quasihomogeneous, such that even though their global degree of nonseparability remains constant, locally it decreases to a minimum value as z -> infinity. We corroborated this quantitatively using the Hellinger distance, a novel metric for vectorness that applies to spatially disjoint vector modes. To the best of our knowledge, HCVBs are the second family of vector beams featuring this behavior, paving the way for applications in optical tweezing or information encryption.(c) 2023 Optica Publishing Group

Automated summary

In this work, a new family of vector beams called helico-conical vector beams (HCVBs) is proposed and experimentally demonstrated. The spatial degree of freedom of the beams is encoded in the helico-conical optical beams. The study finds that the transverse polarization distribution of the beams evolves from nonhomogeneous to quasihomogeneous during propagation. The Hellinger distance metric is used to quantitatively verify this behavior. HCVBs are the second family of vector beams to exhibit this behavior, which opens up possibilities for applications in optical tweezing or information encryption.