Directional polarization vortex nanofocusing with a plasmonic lens

The plasmonic lens, enabling researchers to focus the input light to a specific spatial position in the form of surface plasmon polaritons, is attracting much interest benefiting from the tight focusing and nanoscale confinement of light. Traditional plasmonic lenses mainly concentrated on the chiral and the structured light with a circularly polarized state or a phase vortex, while the polarization vortex was ignored. Here, we put forward a plasmonic polarization vortex lens (PPVL) to directionally manipulate the input polarization vortex beam to the designated focus. Two-mode nanofocusing is realized by combining two orthogonal PPVLs. It exhibits a high extinction ratio of and a full width at half-maximum of 0.6-1 µm. These findings can motivate the applications for on-chip manipulation of polarization vortices and extend the applications of plasmonic lenses in integrated optics.