Anisotropic Plasmonic Metasurfaces with Linear Polarization‐Dependent Focusings

Abstract

AbstractAs a burgeoning approach to modulate electromagnetic waves, metasurfaces fascinate many researchers. However, it is a persistent problem to realize independent wavefront tailoring in different polarization states. In this work, anisotropic plasmonic metasurfaces are presented with linear polarization‐dependent focusings. The designed plasmonic meta‐atoms consist of cross‐shaped gold, silica spacer, and gold substrate. Phase modulation in different polarization channels is independently achieved by adjusting the dimensions of cross‐shaped gold in x‐ and y‐directions. Three metasurfaces are presented to verify linear polarization‐dependent focusings at 200 THz. First, a focusing metasurface is designed with focal lengths of 5.2 µm under x‐polarized incidence and 6.5 µm under y‐polarized incidence. Second, by applying convolution operation, the second metasurface exhibits different focusings with different deflection angles at opposite directions under orthogonally polarized incidences. Finally, a multi‐focal metasurface is demonstrated, which switches between dual‐ and quad‐focal points depending on polarization state. The work may provide a novel platform for near‐infrared integrated photonics.