Purcell factor for point-like dipolar emitter coupling to 2D-plasmonic waveguides

We theoretically investigate the spontaneous emission of a point--like dipolar emitter located near a two--dimensional (2D) plasmonic waveguide of arbitrary form. We invoke an explicite link with the density of modes of the waveguide describing the electromagnetic channels into which the emitter can couple. We obtain a closed form expression for the coupling to propagative plasmon, extending thus the Purcell factor to plasmonic configurations. Radiative and non-radiative contributions to the spontaneous emission are also discussed in details

Molecular Lifetime Changes Induced By Nanometer-Scale Optical-Fields

We present a new practical scheme to study the spectroscopic properties of molecules embedded in optically complex surroundings. The response function accounting for the modification of the spectroscopic behavior of the molecules is derived self-consistently in direct space through the numerical solution of Dyson's equation. We apply this scheme to investigate near-field optical effects due to fluorescence phenomena. Experimentally relevant examples show that the dramatic decay of the molecular lifetime upon approaching a surface defect could achieve well-resolved imaging of subwavelength structures

Field Susceptibility Of A Composite System - Application To Van-Der-Waals Dispersive Interactions Inside A Finite Line Of Physisorbed Atoms

The growing interest in the study of natural or artificial nanoscale structures stabilized by a corrugated surface calls for specific models adapted to the awkward symmetry of such systems. In this work the field susceptibility of a system composed of a finite number of micro-systems interacting with a solid surface is derived from a Dyson's type equation. The many-body character of the interactions between each particle, including reflection with the solid surface, is taken into account by a self-consistent procedure. We show that the calculation of this susceptibility provides a good basis to obtain the van der Waals dispersion energy inside a finite line of physisorbed atoms. We also discuss the possibility of applying this method to study optical energy transfer in complex systems.NA

Dielectric versus topographic contrast in near-field microscopy

Using a fully vectorial three-dimensional numerical approach (generalized field propagator, based on Green's tensor technique), we investigate the near-field images produced by subwavelength objects buried in a dielectric surface. We study the influence of the object index, size, and depth on the near field. We emphasize the similarity between the near field spawned by an object buried in the surface (dielectric contrast) and that spawned by a protrusion on the surface (topographic contrast). We show that a buried object with a negative dielectric contrast (i.e., with a smaller index than its surrounding medium) produces a near-field image that is reversed from that of an object with a positive contrast. (C) 1996 Optical Society of America

Iterative Scheme For Computing Exactly The Total Field Propagating In Dielectric Structures Of Arbitrary Shape

We present a new approach to the computation of an electrical field propagating in a dielectric structure. We use the Green's-function technique to compute an exact solution of the wave equation. No paraxial approximation is made, and our method can handle any kind of dielectric medium (air, semiconductor, metal, etc.). An original iterative numerical scheme based on the parallel use of Lippman-Schwinger and Dyson's equations is demonstrated. The influence of the numerical parameters on the accuracy of the results is studied in detail, and the high precision and stability of the method are assessed. Examples for one and two dimensions establish the versatility of the method and its ability to handle structures of arbitrary shape. The application of the method to the computation of eigenmode spectra for dielectric structures is illustrated

Generation Of Optical Standing Waves Around Mesoscopic Surface-Structures - Scattering And Light Confinement

Optical scanning probe devices offer an extremely efficient way of collecting local information on the complex structure of optical electromagnetic fields lying near a surface. This paper discusses recent theoretical efforts to develop an efficient method for the calculation of the field distributions in experimentally relevant near-field and integrated optics systems. In order to overcome the obstacles inherent in the matching of the electromagnetic boundary conditions on the surface of complex objects, the discussion is presented in the framework of the integral-equation formalism. This treatment is based on the field-susceptibility Green-function technique applied in real space. Two original numerical schemes, both based on a different discretization procedure, are discussed, and several numerical applications on systems of experimental interest are presented. Particularly, the problem of near-held distribution around three-dimensional objects of various sizes and shapes is investigated as a function of experimental parameters