COMPUTING THE OPTICAL NEAR-FIELD DISTRIBUTIONS AROUND COMPLEX SUBWAVELENGTH SURFACE-STRUCTURES - A COMPARATIVE-STUDY OF DIFFERENT METHODS

Some 15 years ago, optical topographic signals with subwavelength reso lution were obtained independently by several experimental teams. Sinc e this exploratory period, a growing number of experimental configurat ions have been proposed and continuously developed. Simultaneously, th is research field was supported by different theoretical works, aimed at developing our understanding of the interaction of optical fields w ith mesoscopic objects. Over the past three years, several theoretical frameworks have been proposed (Green's functions, field susceptibilit y, boundary conditions methods, multiple multipoles expansions, etc.). In this paper, an attempt at a careful comparison between two classes of numerical models is presented. Using the same test object, we disc uss and compare the numerical solutions issued from a reciprocal-space perturbative method (Rayleigh approximation) and the solution origina ting from a direct-space integral approach (Green's function or field susceptibility). The discussion is given for different values of the r elevant experimental parameters. The convergence of both approaches is investigated.