Photonic spin Hall effect based on broadband high-efficiency reflective metasurfaces

Through the introduction of a broadband (∼1µm) high-efficiency (average above 90%) half-wave plate in the near-infrared (NIR) region, reflective Pancharatnam-Berry metasurfaces that can generate high-intensity (above 90%) left-circular polarization (LCP) and right-circular polarization (RCP) light for broadband (∼900nm) are designed. It provides a method to generate broadband high-efficiency circularly polarized (CP) light, which is a rare complex process in traditional chiroptical spectroscopy. To further show the broadband high-efficiency function of the meta-atom, a broadband high-efficiency reflective vortex beam generator based on metasurfaces is designed for RCP light in the NIR region. Moreover, with the appropriate arrangement, the metasurfaces are able to focus the vortex beam into a point to increase the intensity of the generated vortex beam.