Diffraction-induced enhancement of optical spin Hall effect in a dielectric grating

The enhancement of the optical spin Hall effect (OSHE) of a transmitted beam has been achieved in a small incident angle of a sub-degree scale. The OSHE at a large incident angle can be beneficial in optical applications, such as polarization-dependent sensors and filters, but studies to increase the OSHE at a large incident angle have been elusive in transmission mode. We propose a dielectric grating on a metal layer to achieve the grating-induced increase of the OSHE. The polarization-dependent transmission and OSHE that reaches several wavelengths are numerically demonstrated. We also show the tunability of the operating wavelength and incident angle of the OSHE by changing materials and geometrical parameters.