3D interaction of Gaussian beams with dichroic surfaces for the modeling of quasi-optical systems

In quasi-optical systems, dichroic surfaces are used to split, filter, or mix signals. Such surfaces cannot be modeled by existing Gaussian-beam methods. In this article we propose a technique to model the interaction of a Gaussian beam (GB) with a dichroic surface based on a matching in the spectral domain. For a GB illumination of the surface, the reflected and transmitted fields are approximated by one reflected and one transmitted Gaussian beams. Their characteristics are determined by means of the spectral matching through a second-order approximation of the dichroic surface response when excited by plane-waves. Numerical experiments and comparisons with reference solutions show the efficiency of the method in terms of accuracy and computation time.