A beam of light may exhibit a spatially varying polarization distribution. Furthermore, the polarization can also be locally singular or undefined, similar to the case of phase singularities found in scalar fields. In this context, Nye introduced a classification of such polarization singularities, which provides a very useful language for the study of polarized fields.
If electromagnetic fields get spatially confined, exotic polarization phenomena and topologies can be observed. For instance, Freund proposed the appearance of so-called optical polarization Möbius strips in tailored three-dimensional electromagnetic field distributions created by intersecting two differently shaped and polarized light beams. The existence of such exotic structures was recently also proven experimentally for tightly focused polarization tailored light beams.
In this presentation, we will briefly introduce our experimental scheme for measuring the electromagnetic field distribution of light at the nanoscale. Furthermore, we will review our recent and ongoing work on three-dimensional polarization topologies created by tight focusing of tailored or conventionally polarized light beams. We will also elaborate on the connection between points of transverse angular momentum and the existence of (Möbius-like) polarization structures in the propagation plane.