Effect of change in CaO concentration on spectroscopic properties of Tm3+ ions in phosphate glasses

Glasses of particular composition 50 P2O5-(25-x) CaO-22 Na2O-3 K2O: x Tm2O3 (0.2 x < 1.0 mol %) were prepared using conventional melt quenching. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterization studies reveal that the samples have amorphous nature. Further, spectroscopic investigations viz., optical absorption and fluorescence for all samples have been carried out in visible and NIR regions at room temperature. The absorption spectra has exhibited six bands and corresponding transitions have assigned. Similarly, the emission spectra has exhibited six bands in visible region when excited at 456 nm; two bands in NIR region excited at 698 nm. The reasons for variations in intensities and spectral positions of all bands have been discussed in detail with increase in concentration of thulium ions in addition to their structural changes.