Figure 1. The schematic of the proposed 3D PBSs.

(a) The waves deflected by passing through an isotropic GRIN planar lens, in which the vertical and horizontal polarizations cannot be separated. (b) The side view (xoz) of a3D PBS made of a single slab AMS1, in which only the vertical polarization is deflected to the angle of θ. (c) The side view (xoz) of a 3D PBS made of two slabs AMS1 and AMS2, in which both vertical and horizontal polarizations are deflected to angles of θ₁ and θ₂ independently. (d) The 3D view of the PBS, in which the vertical/horizontal polarization is deflected to a spatial direction of (θ, φ) by passing through the PBS.