Metasurface-based near-field polarization transformer for localized light

Polarization is a basic electromagnetic unit of information. It can easily be controlled and adjusted for plane waves propagating in the bulk media. However, it is still a challenge to manipulate the polarization of the localized light, i.e. in the near-field region.

In this work, we discover the near-field polarization degree of freedom offering two configurations for the practical implementation based on (i) all-dielectric metasurfaces in visible and near-infrared ranges, and (ii) self-complementary metasurfaces in microwaves. The first approach assumes a general design strategy for all-dielectric nanostructures that supports TE-TM degenerate guided modes. It is broadly applicable across a wide spectral range, including the visible, infrared, terahertz, and microwave regimes. In what follows, we consider a metasurface consisting of identical disk-shaped high-index dielectric resonators. Each disk exhibits the Mie resonances, and we adjust the collective Mie-like response. The second approach is based on the Babinet’s duality principle implemented in a self-complementary metasurface. It has been recently investigated that surface waves supported by the self-complementary metasurface exhibit degenerate TE-TM dispersion in certain directions, leading to a near-field polarization degree of freedom.

Finally, we demonstrate the excitation of surface waves with on-demand polarization and a planar compact near-field waveguide polarizer. Both devices are subwavelength and have been verified experimentally for microwaves. The results obtained form a new direction for near-field polarization photonics, leading to a plethora of compact planar polarization devices for manipulating localized light.