Diffraction-limit-free vortex-antivortex pair of electromagnetic fields.

The paired generation of vortices and antivortices is studied across multiple fields, including magnetic materials and Bose-Einstein condensates. In optics, while optical vortex-antivortex pairs have been realized in free space, those in evanescent fields were unaddressed. Recent research has shown that the formation mechanism of newly discovered topological quasi-particles, like photonic skyrmions, is closely related to the existence of vortices and antivortices in evanescent fields. Here, we demonstrate, what we believe is for the first time, the diffraction-limit-free vortex-antivortex pair of Poynting vector in evanescent fields. It is found that the separation between the vortex and antivortex can be adjusted through the spiral phase of the incident field, and this separation is not constrained by the diffraction limit. This work provides new insights into the underlying mechanisms of the topological quasi-particles, as well as in developing applications in super-resolution microscopy and precision metrology.