Modified self-consistent approach applied in near-field optics for mesoscopic surface defects

Near field optical microscopy (NOM) offers an efficient way of collecting local information on the optical electromagnetic fields lying in the vicinity of an object. In this paper we calculate the near-field distributions of mesoscopic/nanometric surface structures based on a modified self-consistent integral-equation formalism (SCIEF) in real-space representation. The field-susceptibility Green-function technique and the unretarded approximation are applied. Two kinds of three-dimensional surface structural defects, protrusion and hollow with various sizes and shapes, are investigated in detail. This shows that the pattern of near-field distribution depends strongly on the characteristics of illumination light, such as total-internal-reflection angle and polarized direction of incident field as well as the position of the observation plane. We also discuss the effect of interference for the larger size single defect and between adjacent defects in multiple surface defect samples. The simulation results demonstrate that this modified SCIEF is a very useful and efficient approach for complex shape of defects with nanometric size on the surface of structures.