Asymmetrical photonic spin Hall effect based on dielectric metasurfaces

Abstract

The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spin-controlled nanophotonic devices. However, realization of asymmetrical photonic spin Hall effect is still a challenge with a single optical element due to the conjugation of Pancharatnam-Berry phase, which reduces the flexibility in various applications. Here, we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response. The metasurface consists of an array of dielectric nanofins, where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces, which enables to break the conjugated characteristic of phase gradient. Thanks to the superiority of the phase modulation ability, when the fabricated metasurface is under normal incidence with 1550 nm in wavelength, the LCP light exhibits an anomalous refraction angle of 28.9°, while the RCP light transmitted directly. The method we propose can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities, especially with metasurfaces in a compact space.

Active manipulation of the plasmonic induced asymmetric photonic spin Hall effect

“…and LCP components have unequal amplitudes, called as the asymmetric photonic SHE (APSHE) [14][15][16][17]. The APSHE has attracted considerable interest in the transformation between symmetric and asymmetric photonic SHE [18,19], multichannel switching [20,21] and multi-dimensional polarization manipulation [22,23]. Nevertheless, the methods about modulating the spin splitting shift of the APSHE must to refabricate the structural devices for changing the internal parameter, such as refractive index [24] and thickness [25], or the geometry of original structure [22,23].…”

“…The APSHE has attracted considerable interest in the transformation between symmetric and asymmetric photonic SHE [18,19], multichannel switching [20,21] and multi-dimensional polarization manipulation [22,23]. Nevertheless, the methods about modulating the spin splitting shift of the APSHE must to refabricate the structural devices for changing the internal parameter, such as refractive index [24] and thickness [25], or the geometry of original structure [22,23]. Therefore, it is necessary to explore a method for actively manipulating the asymmetric spin splitting shift by means of altering the external environment, such as external electric field and magnetic field, etc.…”