Formation mechanism of optical waveguide in α-Quartz by ultrashort pulse laser

Optical waveguides are crucial in the development of integrated optical circuits. This study examines their formation in dielectric materials using ultrashort pulse laser direct writing. Emphasizing the significance of the processing parameters for writing low-loss waveguides, we explored the underlying mechanisms through in situ observations of internal modifications and a detailed analysis of electron density and refractive index changes. Employing a combination of pump-probe imaging and Mach-Zehnder interferometry, we reveal the dynamics of laser-induced modifications in quartz, highlighting the influence of spatial overlap and irradiation spacing. Our research offers insights into the micro-level phenomena that affect the overall waveguide performance, thereby providing enhanced fabrication methods.