NEW LANTHANIDE-DOPED FLUORIDE-BASED VITREOUS MATERIALS FOR LASER APPLICATIONS

By careful control of the immediate environment of rare-earth (RE) ion s as verified by site-selective photoluminescence, extended X-ray abso rption fine structure and transmission electron microscopy (image, mic rodiffraction and microanalysis), a new class of laser material has be en devised: the composition of starting materials-and the thermal anne aling conditions have been carefully controlled in such a way that the local crystal field of the RE ion is the same as in a polycrystalline powder. This allows a vitreous material with a much reduced inhomogen eous linewidth to be obtained. Because of this reduction, enlarged las er cross-sections have been obtained with ratios ranging from 1.3 to 1 .5 with respect to ZrF based glasses.