Enhancement of Optical Spin-Orbit Coupling in Anisotropic ENZ Metamaterials

Vector vortex beams which possess complex intensity and polarisation patterns, and phase or polarisation singularities are important in a variety of applications ranging from high resolution imaging and data transmission to nonlinear optics and quantum technologies. Here, we theoretically analyse the effect of vector vortex beams propagation through strongly anisotropic metamaterials exhibiting epsilon-near-zero behaviour. The interaction of the metamaterial with longitudinal field of the vector beams results in a strong modification of the polarisation distribution, with the metamaterial acting as an azimuthal polariser. The dependence on the local ellipticity of the field is also investigated revealing conversion of spin angular momentum to orbital angular momentum and polarisation structure vorticity, mediated by the longitudinal field. The results show the promise of an anisotropic metamaterial platform for manipulation of polarisation properties of and spin-orbit coupling in vector vortex beams.

Automated summary

In this paper, we theoretically analyze the propagation effect of vector vortex beams through strongly anisotropic metamaterials exhibiting epsilon-near-zero behavior. The study shows that the interaction of the metamaterial with the longitudinal field of the vector beams can significantly modify the polarization distribution, acting as an azimuthal polarizer. The dependence on the local ellipticity of the field is also investigated, revealing conversion of spin angular momentum to orbital angular momentum and polarization structure vorticity mediated by the longitudinal field. These results demonstrate the potential of anisotropic metamaterial platform for manipulating the polarization properties and spin-orbit coupling of vector vortex beams.