Evanescent and propagating electromagnetic fields in scattering from point-dipole structures

We investigate the propagating and evanescent field contributions in the scattering of an electromagnetic field from a collection of interacting electric point dipoles. Having applications of scanning near-field optical microscopy (SNOM) in mind, we study three different geometries of dipoles placed close to a bulk surface. One of them is chosen to allow a direct comparison with the results recently put forward in the literature [J. Mod. Opt. 44, 327 (1997)] and to point out the discrepancies in the near zone between the held decompositions applied in that paper and in our work. The other two geometries have been selected to illustrate SNOM action in the illumination and collection modes. Within the point-dipole model we investigate the effects of the probe-dipole polarization on the propagating and evanescent fields in the sample-probe system during the scanning of the probe at different heights above the sample. (C) 2001 Optical Society of America.