Thin anisotropic metasurfaces for simultaneous light focusing and polarization manipulation

The possibility of integration of two important categories of optical components, i.e., circular polarizer and lens, into a thin plasmonic metasurface is examined, for the realistic case when metal losses cannot be neglected, for example when operating in the visible spectrum, or at infrared when non-noble metals are used. We introduce a metasurface made of nanoantennas that offer enough degrees of freedom to control both amplitude and phase of the reflection coefficient. First a theoretical formulation is developed and then an optimal design for a polarizing lens at mid-infrared wavelengths near 4.3 μm is presented. A two-dimensional array of Y-shaped nanoantennas with polarization-dependent and spatially varying phase response offers the possibility of balancing the losses experienced by the x- and y-polarized incident fields and is the basis for such a compact polarizing lens.