Experimental
The Sm3 +-doped phosphate and fluorophosphate glasses were prepared by conventional melt quenching technique [24] using appropriate quantities (in mol%) of Al(PO3)3, KH2PO4, Sr(PO3)2, KF and Sm2O3. The glass compositions (in mol%) are shown in Table 1. Approximately 20 g of batch composition was thoroughly mixed and melted in an electric furnace at 1075 °C for about 90 min in a platinum crucible. The melt was then air quenched by pouring it on a preheated thick brass plate. The glass samples were annealed at 350 °C for 12 h to remove thermal strains and then polished for optical measurements [24]. The refractive indices of the samples were determined with an Abbe refractometer using monobromo naphthalene as an optical coating with an accuracy of ± 0.001 and the density measurements were carried out using Archimedes principle with water as an immersion liquid.