Polarization effects in the optical interaction between a nanoparticle and a corrugated surface: implications for apertureless near-field microscopy

We put forward rigorous two-dimensional numerical calculations of the electromagnetic interaction between a nanometric tip and a corrugated dielectric interface when the tip scans the surface at nanometric distance; The surface is illuminated from its dielectric side by ap-polarized wave at normal incidence or under total internal reflection. Large tip-substrate optical interactions appear for small distances between these two bodies. The far-field images produced by recording the intensity scattered by either the tip or the sample are analyzed in terms of several experimental parameters, namely, the angles of incidence and observation, the dielectric permittivities of the tip and the surface, and the tip-sample distance. The influence of the component of the electric field normal to the surface is discussed. The role of periodic modulation of the vertical position of the tip is also investigated. (C) 1998 Optical Society of America.