Modeling and simulation-based characterization of periodic absorbers for partially coherent fields

Tihon, Denis [UCL]

The absorption of electromagnetic fields plays an important role in many applications such as the energy collection, using thermal or photovoltaic solar panels, or space observation at infrared and optical frequencies, which is based on bolometers. For all these applications and many others, a complete and efficient characterization of the absorption capabilities of a given structure is required. Moreover, in most applications, the fields absorbed by the structure are only partially spatially coherent, since they originate from thermal random fluctuations. This aspect should be included in the characterization. The aim of this thesis is twofold. First, an efficient simulation software based on the Method of Moments (MoM) is developed. We propose several improvements to accelerate the computations and deal with complex geometries. For the first time, a fully-analytical method is provided for the evaluation of the singular integral involved in the MoM. Second, the simulation tool is used to characterize different kinds of plasmonic structures using the Energy Absorption Interferometry. It is shown that, in the structure studied, the absorption is mainly mediated by evanescent surface modes creeping along the surface of the structure. By adding a scattering layer, the incident fields can be coupled to the surface modes and absorption can be greatly increased.