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With the recent discovery of three dimensional Dirac semimetals, their integrations with the optoelectronic devices allow the novel optical effects and functionalities. Here, we theoretically report the photonic spin Hall effect in a periodic structure, where three dimensional Dirac semimetals and the dielectric materials are assembled into the stack. The incident angle and frequency dependent spin shift spectrum reveals that the spin shifts of the transmitted wave in this structure emerge the obvious peaks and valleys for the horizontal polarized wave and their magnitudes and positions display a distinct dependence on the incident angle around the specific frequency. These observations originate from its zero value of the effective perpendicular permittivity and its greatly reduced transmission in the multilayered structure, whose mechanism is different from those in the previous works. Moreover, both the peaks and valleys of the transmitted spin shift are significantly sensitive to the Fermi energy of three dimensional Dirac semimetals, whose magnitudes and positions can be tuned by varying it. Our results highlight the vital role of three dimensional Dirac semimetals in their applications of the spin photonic devices and pave the way to explore the tunable photonic spin Hall effect by engineering their Fermi energies. [ABSTRACT FROM AUTHOR]

BK7 glass has an unusual temperature-dependent refractive index and thickness, which provides a promising platform for uncovering the temperature-related optical phenomena and applications. Here, we theoretically demonstrate that monolayer graphene based BK7 glass grating structure has two Goosâ€"Hänchen (GH) peaks with respective magnitudes of 2564 λ and 1993 λ , and their corresponding reflectances are also high. The electromagnetic field distribution in this structure directly reveals that the enhanced GH shifts can be ascribed to the excitation of the guide mode resonances in the waveguide dielectric layer below BK7 glass grating structure and their high reflectances are granted by the constructive interferences between the reflected waves. In addition, the magnitudes of the GH peaks can be controlled by the temperature of BK7 glass as well as the chemical potential of monolayer graphene. We also evaluate the temperature sensing property of this structure based on the GH shifts and find that its maximum temperature sensitivity can be up to 5.0017 Ă— 10 4 ÎĽ m ° C âˆ' 1. The enhanced and controlled GH shift presented in monolayer graphene based BK7 glass grating structure shows promise for the applications, such as, optical sensors, temperature sensors, and optoelectronic detectors. [ABSTRACT FROM AUTHOR]

Bilayer graphene, composed of two layers of monolayer graphene in AB stacking order, has emerged as an alternative platform for atomically thin plasmonic and optoelectronic devices. However, its behavior of photonic spin hall effect remains largely unexplored. In this work, we have theoretically observed that bilayer graphene has two obvious discontinuities but monolayer graphene only has a single step in the spectra of the spin shifts as a function of wavelength at the Brewster angle over the midinfrared frequency range, which enables a possible route of distinguishing monolayer graphene and bilayer graphene. Additionally, the magnitudes and positions of the peak and valley values in the spectrum of spin shifts of bilayer graphene can be tuned by its Fermi energy. We also achieved the enhanced out-of-pane spin shift of the glass-AB stacking bilayer graphene-air structure at both the Brewster angle (33.55°) and the critical angle (41.31°) with the aid of the high order of Laguerre-Gaussian beam. The realization of large and controlled spin shift in bilayer graphene indicates its promising applications in precision measurements and refractive index sensors at the midinfrared frequency region., (© 2022 IOP Publishing Ltd.)