Optical chirality without optical activity: How surface plasmons give a twist to light

Light interacts differently with left and right handed three dimensional chiral objects, like helices, and this leads to the phenomenon known as optical activity. Here, by applying a polarization tomography, we show experimentally, for the first time in the visible domain, that chirality has a different optical manifestation for twisted planar nanostructured metallic objects acting as isolated chiral metaobjects. Our analysis demonstrate how surface plasmons, which are lossy bidimensional electromagnetic waves propagating on top of the structure, can delocalize light information in the just precise way for giving rise to this subtle effect.Comment: Opt. Express 16, 12559 (2008

Surface Plasmon mediated near-field imaging and optical addressing in nanoscience

We present an overview of recent progress in plasmonics. We focus our study on the observation and excitation of surface plasmon polaritons (SPPs) with optical near-field microscopy. We discuss in particular recent applications of photon scanning tunnelling microscope (PSTM) for imaging of SPP propagating in metal and dielectric wave guides. We show how near-field scanning optical microscopy (NSOM) can be used to optically and actively address remotely nano-objects such as quantum dots. Additionally we compare results obtained with near-field microscopy to those obtained with other optical far-field methods of analysis such as leakage radiation microscopy (LRM)