Realization and characterization of randomly disordered fiber with tellurite glass

Silica multi-core optical fibers have been the common fiber for imaging but the growing interest in other fields aside telecommunication, such as medical and biological, requires new solutions. In these fields the wavelengths of interest are in the near and mid-IR known for their harmless interaction with biomedical objects. To operate in this range new materials are required, and tellurite glasses offers a broad transparency window for this. They also have a large refractive index, high thermal and chemical stability, low intrinsic loss, and they are easy to modify with dopants. Issues with the old silica multi-core fibers are not only caused by the material but by the quality of the image transported by them, that’s why new designs are studied. It has been demonstrated the higher quality of the images transmitted by disordered fibers with different materials compared to what is achievable with commercial multi-core fibers. The purpose of this thesis was to design, fabricate, and characterize a tellurite-air disordered optical fiber with a clad of commercial silica glass for imaging in the mid-IR region. The focus has been on the choice of the clad glass and its design to improve the quality of the fiber and increasing the chances of success of the drawing. The characterization techniques were made to identify the thermo-mechanical characteristics and optical properties of the glass chosen, a TeO2, Nb2O5, GeO2, PbO and ZnF2 (TNGPZ).The DTA showed a good stability against devitrification with a ΔT of 227.8°C with a Tg of 360.2°C while the refractive index measurement show a value of 2.0683 for 1533 nm. The fiber could not be realized but the characterization showed a large refractive index difference and transmittance in the mid IR-region, even if with important losses due to OH impurities. These results met the expectations and shows promising results for the fabrication of this kind of fiber.