Fabrication of waveguides with femtosecond pulses in nonlinear glass

Abstract

Femtosecond lasers stand out for having very high peak intensities and wide spectral bandwidth, making them great tools in the study of phenomena in nonlinear optics. From this point of view, one of its applications is in the construction of microstructures inside certain vitreous materials with great precision, without affecting the surface or regions peripheral to the points of interest. In this project, such structures will be waveguides. It is noteworthy that this area is relevant since the advancement of the field of photonics reveals a favorable future for the use of technologies in this category, not only in relation to waveguides in the glass but also with regard to the process of microfabrication using ultrashort pulses. Furthermore, the glassy systems that will be used here (TeO2; NbO2 and B2O3), in addition to providing non-linear effects worthy of study, constitute a research area still under development, showing space for significant contributions to the paradigm of microstructures in the glass. In this context, a Ti: Sapphire femtosecond laser (50 fs, 800 nm, and 5 Mz) focused with microscope objective lenses will be used. The sample, in turn, will be free to move three-dimensionally in relation to the laser, allowing control of where the focus occurs. Therefore, this process depends on several factors - such as pulse energy, laser sweep speed, and numerical aperture of the focusing lens - that need to be measured and studied to lead to optimal manufacturing conditions. Not only that, once generated, these structures also need to be verified. Therefore, the analysis of the transverse profile of the waveguides will be performed by microscopy (optical and electronic), once the surface perpendicular to the irradiated area has been properly polished. However, by varying the depth where the guides will be engraved, we can determine and document the limit of distances where it is still possible to obtain acceptable results for future applications in optical devices. (AU)