Glass-ceramics coating of silica microspheres

Silica spheres with diameters in the order of 100 ?m were coated by Er3+-activated silica-hafnia films and then annealed in order to induce formation and growth of nanocrystals. The spectroscopic and morphologic properties of the spheres have been characterized by photoluminescence and atomic force microscopy techniques, respectively. The preliminary information are discussed, taken in account the previous consolidated results obtained in the case of amorphous and glass-ceramic waveguides as well as spherical microresonators coated by amorphous silica-hafnia films.