Polarization Conversion and Optical Meron Topologies in Anisotropic Epsilon-Near-Zero Metamaterials.

Plasmonic metamaterials provide a flexible platform for light manipulation and polarization management thanks to their engineered optical properties with exotic dispersion regimes. Here we exploit the enhanced spin-orbit coupling induced by the strong anisotropy of plasmonic nanorod metamaterials to control the polarization of vector vortex beams and generate complex field structures with meron topology. Modifying the degree of ellipticity of the input polarization, we show how the observed meron topology can be additionally manipulated. Flexible control of the state of polarization of vortex beams is important in optical manipulation, communications, metrology, and quantum technologies.