Thesis defense of Elise BAILLY

Thesis defense of Elise BAILLY, PhD student in the Nanophotonics group of the Laboratoire Charles Fabry , on 30 May 2023 at 10:00 am in the Auditorium of the Institut d'Optique Graduate School in Palaiseau, on the topic: "Control of spontaneous emission by a cavity assembly of thermalised emitters. Theoretical and experimental study ". 

Abstract: "The aim of this thesis is to develop a model and techniques for controlling light emission from an assembly of fluorophores in the visible range. Miniaturising light sources is a major challenge in order to reduce their size and therefore production costs. It also makes it easier to integrate these sources into other systems. It is now well understood that the emitter environment can modify the properties of the light emitted. In this thesis, we explore ways of shaping this electromagnetic environment in order to obtain a miniaturised source whose emission is directive. The first part is devoted to the study of spatial coherence, which is necessary to obtain directivity. We establish a general absorption-coherence relationship that allows us to calculate the spatial correlation of the fields using an absorption calculation. This enables us to study the emission properties of a system composed of dye molecules deposited on silver and to highlight the role of surface waves in the appearance of spatial coherence. Secondly, we show that photoluminescence in the presence of the resonant environment can be calculated using local Kirchhoff's law. Using this method, we model the photoluminescence emitted by a complex system composed of two types of fluorescent emitters deposited on a silver film. We demonstrate energy transfer between these two families of emitters. Finally, we take advantage of the previous results to digitally design directive photoluminescent sources, composed of nanoplatelets deposited on a metallic metasurface acting as a resonant cavity. These sources are manufactured in a clean room and experimentally characterised. The agreement of the experimental results with the theory demonstrates the scope of local Kirchhoff's law in the design of innovative light sources."