Fabricação e caracterização de guias de onda em vidro usando a técnica de escrita direta

Abstract

The direct-writing technique for fabrication of waveguides in glass is a promising advance for the areas of Quantum Information and Quantum Computation, since it allows for rapid, three-dimensional fabrication of integrated photonic devices. This technique consists in focusing an ultra-fast laser inside a moving glass substrate, causing a change inrefractive index on the focal region, forming the waveguides. The aim of this dissertation was to study the direct-writing method in the fabrication of some samples, made at the Photonics group of Universidade de São Paulos Instituto de Física de São Carlos (IFSC-USP). We characterized the fabricated waveguides regarding their geometry using Confocal microscopy, their efficiency on light guiding by means of coupling a lasers light, and their refractive index using Defocusing Microscopy technique. This technique was developed by UFMGs Laboratório de Física de Sistemas Biológicos, and allows a direct measurement of the refractive index of a phase object in a defocused microscope. We worked with two samples in two dierent kind of glasses, Gorilla Glass and sodalime: 11 waveguides were fabricated inside the former, and 44 in the latter. Our results show waveguides inside Gorilla Glass were more efficient in guiding the light compared to waveguides inside sodalime sample, but both showed transmittance lower than 15%. With the larger amount of waveguides inside sodalime, it was possible to realize thatfemtosecond laser power and samples translation speed at fabrication have main role in the modication of refractive index on the focal region. In possession of this data, we are capable of leading further fabrication to better suit the objectives of these devices on applications in photonic quantum systems.