Search

Taking advantage of the flexible customization of dynamic and Pancharatnam–Berry phases on meta-atoms, spin-decoupled multifunctional metasurfaces have been realized for optical beams of orthogonal circularly polarized lights, which promotes the diverse development of nanophotonic devices. To date, spin-decoupled metasurfaces can only spatially split and deflect beams in coplanar directions not in non-coplanar, limiting further applications. Here, a single metasurface is proposed to experimentally as well as numerically demonstrate the spin-decoupled omnidirectional anomalous refraction. The results indicate that the three-dimensionally omnidirectional dual-beam refractions are attributed to arbitrary engineering of spin-independent phase gradients along any in-plane orientations of the single metasurface. It is believed that the proposed spin-decoupled omnidirectional metasurfaces are promising candidates for multifunctional applications in compact spin-based nanophotonic systems, such as polarized beam splitting, steering, and polarimeter.

The metasurface with elliptical nano-structures containing doubly degenerate geometrical charge is designed to investigate the enhanced spin-orbit optical interactions, numerically as well as experimentally. It is found that localized surface plasmon (LSP) resonance with orbital angular momentum (i.e., rotating SP vortex mode carrying extrinsic orbital angular momentum) can be induced under linearly polarized illumination. On the contrary, the LSP resonance without orbital angular momentum is formed under circularly polarized illumination. Moreover, based on the different LSP modes as results of spin-orbit interaction with alternative geometrical charge, directional propagations of surface plasmon polariton in two orthogonal trajectories depending on spin states of the incident light are presented with experimental demonstration, a phenomenon called photonic spin Hall effect.

SrBi2Ta2O9 thin films were prepared by pulsed laser deposition at different substrate temperatures. Photoluminescence (PL) has been detected at room temperature from the pyrochlore phase in the SrBi2Ta2O9 film deposited at 850 °C. The PL shows five luminescence bands of 330, 365, 407, 490, and 600 nm. And the PL excitation shows six excitation bands of 278, 330, 365, 407, 490, and 600 nm. The one-to-one correspondence of PL and PL excitation spectra reveals a band-to-band excitation and a multienergy-gap structure in the pyrochlore phase in SrBi2Ta2O9 films.

A chiral metallic metastructure composed of bilayer twisted bars is proposed to realize a broadband asymmetric transmission for linearly and circularly polarized incident light, aimed at sustaining high efficiency of unidirectional polarization conversion over the whole operation band. Such a one-way propagation results from the chiral structural arrangement that destroys the rotational and translational symmetries in all directions. Moreover, its ultra-broad bandwidth, mainly depending on the bar length, originates from the subwavelength plasmon coupling between long- and short-bar dipole-like responses. The efficient broadband one-way characteristic exhibits a structure with promising prospects for metadevices capable of unidirectional polarization conversion manipulation.

Polarization control of the light can be realized by ultrathin plasmonic structures, which is generally based on the effect of extraordinary optical transmission. In this paper, we designed a U-shaped plasmon-induced transparent metasurface to investigate the polarization state conversions of resonantly transmitted light through reducing the structural symmetry by rotation. A significant optical polarization conversion capability is found for impinging light with linear as well as circular polarization. In particular, the different polarization conversions between the left-handed and right-handed circular lights manifest the characteristic of circular dichroism. The results are useful for the potential applications such as a broadband quarter-wave plate.