  The polarization behavior of metallic nano-rods has been analyzed by means of
the finite-difference-time-domain method. When the average spacing between the
nano-rods is less than a half wavelength, the layer reflects the light
polarized parallel to the nano-rods, as in a nano-slit. However, when the
spacing is larger than a half wavelength, the metallic surface absorbs the
light, polarized perpendicular to the rods, leading to a polarization reversal.
Multiple layers of nano-rods can make a polarizer with a high extinction ratio
and good transmittance.

Optics