Fluorescence spectroscopy and structure of erbium doped tin fluorophosphate glass

Fluorescence, Raman and EXAFS spectroscopy were used to study glasses of Sn-F-P-O composition doped with different amounts of erbium. Increasing intensity of fluorescence with Er concentration in the range 390-600 nm is observed for 340 nm excitation. Raman spectroscopy measurements show that Er$_{2}$O$_{3}$ modifies the glass spectrum with P-F bonds being replaced by Er principally bonding with F. ErF$_{3}$ and SnF$_{2}$ bands are also identified in the Raman spectra of the doped glasses. EXAFS data give a coordination of Sn to O of 1.5 in an undoped sample, while Er coordination is determined to be 9, indicating that ErF3 is the most likely environment for the rare-earth atoms. Glass transition temperature T$_{\mathrm{g}}$ of 80$^{\circ}$C is determined for undoped glass increasing to 87$^{\circ}$C for the samples doped with 0.25 mol. {\%} of Er.