Polarization multiplexed all-dielectric metasurfaces for wavefront manipulation in a transmission mode

All-dielectric metasurfaces are planar structures completely consisting of dielectric materials, which enable the control of phase, amplitude and polarization of light. Due to the good process compatibility and high transmittivity, they have drawn considerable attention in diverse applications for polarization conversion and wavefront manipulation in a transmission mode. Although several kinds of all-dielectric metasurfaces have been reported in literature to achieve wavefront manipulation, they either have only one fixed wavefront output or have susceptible efficiency to the side-wall-angle (SWA) error, which is extremely difficult to be minimized with current top-down fabrication processes. In this work, we propose an elliptical silicon nanopillar array, which possesses a polarization multiplexed response and high transmittivity, and more importantly, it is less sensitive to the SWA error. Two metasurfaces, namely a beam deflector and a vortex convertor, are exemplified to examine the performance of the proposed elliptical nanopillar array at a visible wavelength of 600 nm. We achieve high transmittivity of 76.7% and 81.4% for the beam deflector and the vortex convertor, respectively. Moreover, both the deflecting direction of the beam deflector and the chirality of the generated beam from the vortex convertor can be controlled by the incident polarization. The proposed all-dielectric metasurfaces demonstrate great potential for practical and polarization multiplexed optical elements. (paper)