Localization of Yb3+, Er3+ and Co2+ Dopants in an Optical Glass Ceramics of MgAl2O4 Spinel Nano-crystals Embedded in SiO2 Glass

NATO-Advanced-Study-Institute Meeting on Nano- Structures for Optics and Photonics - Nano-Optics - Principles Enabling Basic Research and Applications, Erice, ITALY, JUL 04-19, 2015; International audience; The main goal of this research is the localization of Yb3+ and Er3+ rare earth ions and Co2+ transition metal ion as dopants in a glass ceramics composed of MgAl2O4 spinel nano-crystals of 10-20 nm size embedded in SiO2 glass. This is the first step of a compact self-Q-switched microchip laser. We conjugate, that is rather rare, both TEM-EDX and optical spectroscopy techniques. The use of TEM-EDX technique associated with both the elemental mapping of each dopant and the direct visualization of the heavier rare earth ions is unique way in luminescent materials which has led to the result that Er3+ and Yb3+ rare earth ions are preferentially located in the spinel nano-crystals. Regarding the Co2+ low concentration, this technique was not enough accurate and finally absorption spectroscopy technique have probed the main presence of Co2+ ions in the spinel nano-crystals. The use of site selective spectroscopy technique applied to Yb3+ structural probes allows to identify the 0-phonon broad line at 975 nm with both that of the disordered glass and that of the spinel inverted phases. A new Yb3+ radiationless center has been pointed out by the presence of a strong absorption line at 970 nm which has been assigned to the strongly perturbed area of the spinel nano-crystallite surface. This dopant characterization worthwhile to be shown in this School by applying both TEM-EDX and optical spectroscopy techniques as a pedagogical case in the research of rare earth ions and transition metal ions localization.