Study and Development of Whispering Gallery Mode Resonators for Technological Applications

Whispering gallery mode resonators (WGR) are optical cavities with very low loss. This property makes them particularly interesting for many applications including sensors and nonlinear optics. Despite all the research devoted to these cavities, many basic aspects of WGR are not completely understood and many issues still inhibit these technologies from being used in real world applications. This thesis aims to address some of these issues. First, this thesis presents an attempt of a non-destructive techniques to accurately measure the absolute radius and refractive index of a WGR. In order to do so, instrumental techniques were developed to first accurately determine the mode order number without relying on approximations and, second, determine the axial position where the radius is being measured. Perturbations of the modes are then studied using the interactions of a tapered fiber and optically trapped nanoparticle. An earlier experiment demonstrated a frequency shift occurs when the nanoparticle is in proximity of the tapered fiber. This effect was not observed in our experiment. This thesis then reviews the Pound-Drever-Hall technique and describes an implementation using a single board computer for many of the electrical components. Lastly, packaging was developed to improve the robustness of the tapered fiber and reverse the degradation of the Q factor due to adsorbed water on the surface of silica SNAPs. The packaging is robust enough to transport the fiber to different laboratories but cannot withstand the temperatures required to remove the adsorbed water