Metasurface for Reciprocal Spin-Orbit Coupling of Light on Waveguiding Structures

Light manipulation through spin-orbit coupling opens new perspectives in photonics and particularly in integrated optics. The reverse spin Hall effect, where the guided wave direction affects the polarization properties of the light scattered by a nanostructure, is a key effect for the development of new functionalities at the connection between integrated structures and free space, and could find application in chiral quantum optics, modulation, and multiplexing. We show that metasurfaces represent a promising platform for the reverse spin Hall effect. Using a periodic array of Lambda-shaped metallic nanoantenna, we control the polarization of the extracted light with the guided wave-propagation direction, but also the number of output directions and the polarization of each one. These results and the versatility of metasurfaces for the spin Hall effect could be extended to various frequencies and materials, such as silicon photonics at telecom wavelength.