Abstract
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.
Highlights
The physical origin of the optical spin Hall effect (OSHE) lies on the finite beam waist of the incident beam, which contains central wave vector components, and other wave vectors slightly deflected from the central beam axis in both in-plane and out-of-plane directions with respect to the incident plane
We numerically demonstrate that these polarization-dependent transmission coefficients lead to high OSHE at a large incident angle, whereas the OSHE is enhanced at a small incident angle in previous scitation.org/journal/app instances
OSHE can be understood to be a consequence of the geometric phase ΦB that is acquired by a deflected wave vector in the polarization space
Summary
Electrons that possess opposite spin may undergo transverse shift along the opposite direction even in the absence of an external magnetic field. This spin-dependent deflection of electrons known as the spin Hall effect is not a unique phenomenon that can only be found in electronic systems, but has analogies in photonics in terms of spin-dependent phenomena, such as transverse splitting, angular splitting, and splitting of exciton–polaritons. Among them, the optical spin Hall effect (OSHE), known as the photonic spin Hall effect and spin Hall effect of light, manifests itself as a spin-dependent and transverse splitting of circularly polarized light at an interface between two media, and is known as the Imbert–Fedorov effect. The physical origin of the OSHE lies on the finite beam waist of the incident beam, which contains central wave vector components, and other wave vectors slightly deflected from the central beam axis in both in-plane and out-of-plane directions with respect to the incident plane. Electrons that possess opposite spin may undergo transverse shift along the opposite direction even in the absence of an external magnetic field.1,2 This spin-dependent deflection of electrons known as the spin Hall effect is not a unique phenomenon that can only be found in electronic systems, but has analogies in photonics in terms of spin-dependent phenomena, such as transverse splitting, angular splitting, and splitting of exciton–polaritons.. Previous studies to increase OSHE in the transmission type have mainly focused on a small incident angle, on the order of milli-radians, in which OSHE is significantly enhanced as the incident angle goes to zero.. We numerically demonstrate that these polarization-dependent transmission coefficients lead to high OSHE at a large incident angle, whereas the OSHE is enhanced at a small incident angle in previous. The diffraction-induced OSHE will be advantageous in optical applications, including filters and sensors
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