Thesis defense of Théo ROUANET, November 16, 2023

Théo ROUANET will defend his thesis on November 16, 2023 at 14:00 a.m., (amphi JP. DOM – IMS Laboratory) on the subject :”Modelling and fabrication of passive photonic devices operating in the visible range: application to optical sensing and highly broadband waveguiding.”.

The development of photonic structures in integrated optics operating at visible wavelengths is becoming a major challenge in various fields such as healthcare, detection, and imaging. The aim of this thesis is to develop various optical structures operating in this range: devices for the detection of specific molecules in aqueous environments and waveguides operating over a wide spectral band. The detection devices were created using two distinct families of materials in order to compare their performance: polymers on a porous silica substrate and silicon nitride (SiN) on a silicon substrate. They rely on transduction based on an optical microresonator (OMR), which exhibits optimal sensitivity in the visible domain where pollutant spectral signatures are documented. The structures are optimized to operate at a single wavelength. Furthermore, we have developed waveguides operating over a wide spectral range in the visible spectrum. These waveguides were made from a single material, silicon oxynitride (SiON), by controlling the refractive index gradient presented by the different layers. By using modeling methods as described and specifically developed models, as well as adapting the cleanroom microfabrication process, initial OMR sensors consisting of ridge waveguides and buried SiON waveguides were fabricated. An optical characterization bench suitable for visible wavelengths was also used to extract the optical performance of these devices and position them within the state of the art. Finally, prospects for this work have been proposed.