Ricerc@Sapienza

Arrays of nanoholes in metal are important plasmonic devices proposed for applications spanning from biosensing to communications. In this work we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the in-plane tilt of the ellipse axes away from the array symmetry lines. The array then differently interacts with circular polarizations of opposite handedness at normal incidence, i.e. it becomes intrinsically chiral. The measure of this difference is called circular dichroism (CD).