Magneto-optical studies of defects in optical glasses

Doped glasses that can be fashioned into efficient optical devices such as lasers or fiber-optic components are highly valued by the telecommunications industry. The optical properties of these glasses are determined, to a significant extent, by the nature of defect centers introduced by either the fabrication process, exposure to electromagnetic radiation, or by the addition of dopant materials. In this dissertation, a series of experiments employing magneto-optical spectroscopic methods were conducted on various technologically-useful optical glasses in order to determine the nature of defect species present. In particular, these techniques allowed for unprecedented insight into the optical properties of defect centers.; First, the magnetic circular dichroism absorption (MCDA) technique was applied to the study of radiation-induced defect centers in Ge-doped silica glasses. Such centers are considered highly important in such optical phenomena as photosensitivity and second harmonic generation (SHG). Through use of MCDA and optically detected magnetic resonance (ODMR), unequivocal correlations were established between various induced defect species and optical absorption bands.; MCDA and ODMR were then utilized in the study of irradiated Ge-doped silica glasses loaded with hydrogen. These glasses are of particular interest since they show greatly enhanced photosensitive properties. Using the aforementioned magneto-optical techniques, paramagnetic hydrogen-related defects were directly attributed to UV-Vis absorptions. In addition, the interplay between preexisting network defects and interstitial H₂ was explored by varying initial network defect concentration and observing the effects on defect production as well as optical absorption and photoluminesence (PL); this gave substantial insight to photochemical processes involving hydrogen and the glass network.; Finally, the magnetic circular dichroism absorption (MCDA) technique was employed to examine Er+3-doped aluminosilicate glasses of varying concentrations. The MCDA data was used to obtain the Faraday Parameters for a number of optical absorption bands, and also to derive the spectroscopic splitting factor, g, for the Er+3 ion ground state. An alternative method of calculating the ground state g value from the saturation behavior of the magnetic circular dichroism signal with increasing field strength was also described. The values obtained by both methods are compared with each other and also with values obtained in other studies.