Optical addressing at the subwavelength scale

The Green dyadic formalism is applied to the study of the optical propertie s of dielectric subwavelength structures integrated in coplanar geometry. W e first consider homogeneous wires with high refractive index featuring sub wavelength cross sections. We show that such wires may have guiding propert ies and that they may be coupled with a local illumination produced by a fo cused Gaussian beam totally reflected at the substrate intel face, When exc ited by the focused beam, these subwavelength optical waveguides (SOW's) pr ovide a confined source of light that could be used to excite a single nano scopic object. Well designed heteregeneous wires resulting From the alignme nt of dielectric particles separated from each other by a subwavelength dis tance are also found to propagate a Gaussian beam excitation over several m icrometers. This propagation occurs with reasonable damping for incident be ams in the visible frequency range. The computed transmission spectra of th ese heterowires may exhibit narrow gaps. Finally, we discuss the relation b etween the optical properties of the SOW and the calculated electromagnetic local density of states.