Coexistence of large photonic spin Hall effect and high efficiency in a dielectric grating structure

Large reflected photonic spin Hall effects have been discovered in various nanostructures under either horizontal (H) or vertical (V) polarized wave. However, their corresponding reflectance efficiencies are always quite low and they generally cannot be enhanced simultaneously for both H and V polarized waves. How to achieve the large photonic spin Hall effects and high efficiencies for both H and V polarized waves at the same wavelength, which are essential for their efficient spin photonic applications, remains acute. To overcome this difficulty, we design one dimensional subwavelength dielectric grating structure and find that it supports the remarkable reflected photonic spin Hall effects under both H and V polarized waves at the same incident angle via well-designed geometrical parameters, which are also accompanied with high reflectances in the visible frequency. We also elucidate that the reflected spin shifts in this structure are related to the incident angle and thus can be engineered by it. Our findings about the dielectric grating structures contribute to an alternative approach to achieve the decent reflected spin shifts and efficiencies for both polarized waves, which enables the next-generation spin photonic devices, such as, precision metrology and quantum information processing.