Laser inscription of high optical contrast in photosensitive oxyfluoride glasses: investigation of silver and fluorine co-mobility & application to large refractive index changes

Abstract

This project addresses the research internship for a period of 8 months at the "Institut de la Matière Condensée de Bordeaux", University of Bordeaux, Bordeaux, France, thanks to the FAPESP for funding doctoral mobility. The aim of this work is to make new contributions in the development of photosensitive oxyfluoride glasses and femtosecond laser inscription of such glasses for the generation of high refractive index optical contrast so as to target applications in integrated photonics. Femtosecond laser inscription is a cost-effective, highly versatile approach that allows for 3D material modifications by means of highly-localized multi-photon energy deposition. Such an irradiation regime gives access to transient out-of-equilibrium states of glasses that cannot be obtained during their synthesis, which provide local modification of the glass. Depending both on the laser irradiation regime as well as on the tailored glass composition, one can address either the glass matrix modification or the fine photochemistry of sensitizing elements, leading to original optical contrast. In this sense, the French group has produced this last decade important works and significant progress in the field of photosensitive glass synthesis and has high expertise in laser inscription for inducing highly-localized optical contrast of linear and nonlinear spectroscopic properties as well as plasmonic response and refractive index modifications at the sub-µm scale in 3D. These skills open up new applications of integrated photonic circuits such as high-sensitivity refractive index evanescent sensors, compact integrated devices such as sub-millimetric long waveguide Bragg gratings or at the macroscopic scale with volume Bragg gratings. More important, it complements the ongoing doctoral project at developing new oxyfluoride glass technologies, to achieve new photonic devices, based in reliable approaches compatible with technological transfer in industry and thus subsequent high socio-economical impacts for the University of Sao Paulo.