  We report the first experiential observation and theoretical analysis of the
new phenomenon of planar chiral circular conversion dichroism, which in some
aspects resembles the Faraday effect in magnetized media, but does not require
the presence of a magnetic field for its observation. It results from the
interaction of an electromagnetic wave with a planar chiral structure patterned
on the sub-wavelength scale, and manifests itself in asymmetric transmission of
circularly polarized waves in the opposite directions through the structure and
elliptically polarized eigenstates. The new effect is radically different from
conventional gyrotropy of three-dimensional chiral media.
