Formation of a Plasmonic Surface Optical Vortex by Evanescent Bessel Light

The total internal reflection of an optical mode with a phase singularity, such as a Bessel beam, can generate evanescent light that displays a rotational property. Notably, using a metallic layer surface, field components extending into the vacuum region have vortex properties besides surface plasmonic features. This vortex retains the phase singularity of the original light, and also maps its associated orbital angular momentum of incident Bessel light of the order l > 0. Additionally to a two-dimensional patterning on the metallic surface, the strongly restricted intensity distribution decays with distance vertical to the metallic surface. The detailed characteristics of this vortex structure depend on the input light parameters and the dielectric mismatch of the media. As well as this, they can be controlled by varying the incident angle and the order of Bessel light.