Fig. 1. (a) Electromagnetic reflection on a flat surface at the pseudo-Brewster angle. Note that the reflection minimum is related to the Zenneck surface wave that propagates along the interface between air and a lossy smooth metal. (b) Electric field distribution at the pseudo-Brewster angle for a posts array.

Fig. 2. Theoretical analysis of the metallic grating.(a) Reflectance of s- and p-polarized light for a smooth gold plate. (b) Reflectance of s- and p-polarized light for a gold plate decorated with subwavelength posts array. (c) Energy flow in the xz-plane when p-polarized light is incident with a angle of 80°. (d) Schematic of the wavevector mismatching at the air-posts interface. (e) and (f) Amplitudes of the electric fields for s- and p-polarization at θ=80°.

Fig. 3. Broadband reflectance and polarimetric imaging.(a) Perspective view of the gold-sample. (b) and (c) FTIR spectra of the gold sample for incidence angles of 70° to 80°. The p- and s-polarizations are indicated in each panel. (d) Perspective view of the chromium sample. (e) and (f) Polarized infrared images of the chromium-sample and a reference sample for p- and s- polarizations. The strong emission at the circumference of the sample is from the silicon dioxide substrate (the diameter of the substrate is 2.5 cm and the structured is fabricated in a square region with a width of 1.5 cm).

Fig. 4. Metallic posts array acting as a reflective waveplate.(a) Reflective phase retardation at different incidence angles for s- and ppolarizations at λ=10.6 μm. The distance between the reference plane and the top of the posts array is 10 μm. The theory is based on the effective impedance and transfer matrix method. (b) Measured ellipticity of the reflected laser beam generated by a CO2 laser (λ=10.6 μm).