Closed-form representations of field components of fluorescent emitters in layered media

Abstract

Dipole radiation in and near planar stratified dielectric media is studied theoretically within the context of fluorescence microscopy, as fluorescent emitters are generally modeled by electric dipoles. Although the main emphasis of this study is placed on the closed-form representations of the field components of fluorescent emitters in layered environments in near- and far-field regions, the underlying motive is to understand the limits of spectral self-interference fluorescence microscopy in studying the dipole orientation of fluorophores. Since accurate calculations of the field components of arbitrarily polarized electric dipoles in layered environments are computationally very time-consuming, a method for finding their closed-form representations is proposed using the closed-form potential Green's functions previously developed for microwave applications. The method is verified on typical geometries used in spectral self-interference microscopy experiments, where a dipole emitter is positioned over a slab of SiO2 on top of a Si substrate. In addition to facilitating efficient calculation of near and intermediate fields of fluorescent emitters, closed-form Green's functions for fields would also play a crucial role in developing efficient and rigorous computational analysis and design tools for optical passive devices such as optical antennas by significantly improving the computational cost of the numerical solution of the integral equation.