Symmetry and reciprocity constraints on diffraction by gratings of quasi-planar particles

Symmetry and reciprocity constraints on polarization state of the field diffracted by gratings of quasi-planar particles are considered. It is shown that the optical activity effects observed recently in arrays of quasi-planar plasmonic particles on a dielectric substrate are due to the reflection of the field at the air-dielectric slab interface and are proportional to this reflection coefficient.Comment: 11 pages, 3 figures, 12 references; minor corrections for better appearanc

On the relationships between constitutive parameters of chiral materials and dimensions of chiral objects (helices)

The relationships between the real constitutive parameters $\varepsilon$, $\mu$ and $\xi$ of a lossless chiral material and the dimensions of short metallic helices, using the quasi-static approximation, are given. Such study is a first step towards the construction of chiral materials, active at microwave and millimeter-wave frequency range, by offering the possibility of controlling and predicting their response