Rare-earth doped sol-gel materials for optical waveguides

Neodymium doped SiO2-Al2O3 samples have been produced by the sol-gel method and characterized by refraction index and fluorescence measurements. TiO2 co-doping has been used to control the refraction index n up to a concentration of TiO2:SiO2 of 1:1 where n has increased from 1.46 to 1.73. Refraction index measurements of thin films have been done by white light interferometry. The fluorescence spectra and lifetimes upon 808 nm excitation have been measured. The results show that TiO2 co-doping of Nd3+:SiO2-Al2O3 sample does not lead to a significant decrease of the fluorescence lifetime. A fiber preform with a neodymium doped sol-gel core has been manufactured and successfully drawn to a fiber, which showed laser action.