Broadband enhancement and switch of photonic spin Hall effect in Dirac semimetal grating structure

Abstract Bulk Dirac semimetals are becoming the potential candidates for the photonic spin Hall investigations because of its three dimensional bulk characteristics and controllable optical properties. Here, we realize an enhanced reflected photonic spin Hall effect in three dimensional Dirac semimetal material-based grating structure, whose magnitude reaches the theoretical upper limit under the horizontal polarization because of its large reflectance contrast under horizontal and vertical polarizations. In particular, due to the contributions of the controllability in the optical parameters of the Dirac semimetal materials, we demonstrate that the reflected spin shift in this grating structure can be engineered by the Fermi energy of the Dirac semimetal. Our work directly highlight the vital role of grating structure in enhancing the spin shifts and provide a promising approach to achieve its manipulation via the property of the Dirac semimetal material, paving the way toward realizing the functional and switchable spin-photonics applications.