Abstract

We show that propagating optical fields bearing an axial symmetry are not truly hollow in spite of a null electric field on axis. The result, obtained by general arguments based upon the vectorial nature of electromagnetic fields, is of particular significance in the situation of an extreme focusing, when the paraxial approximation no longer holds. The rapid spatial variations of fields with a ``complicated'' spatial structure are extensively analyzed in the general case and for a Laguerre-Gauss beam as well, notably for beams bearing a $|l|=2$ orbital angular momentum for which a magnetic field and a gradient of the electric field are present on axis. We thus analyze the behavior of an atomic size light detector, sensitive as well to quadrupole electric transitions and to magnetic dipole transitions, and apply it to the case of a Laguerre-Gauss beam. We detail how the mapping of such a beam depends on the nature and on the specific orientation of the detector. We show also that the interplay of mixing of polarization and topological charge, respectively associated to spin and orbital momentum when the paraxial approximation holds, modifies the apparent size of the beam in the focal plane. This even leads to a breaking of the cylindrical symmetry in the case of a linearly polarized transverse electric field.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.