Investigation of near-infrared luminescence properties of er3+ doped different phosphate glasses for optical amplifier applications

Different phosphate glasses, 69.5P2O5-15Na2CO3-15MCO3 (M= Li, Mg, Ca and Ba) doped with 0.5 mol% erbium were prepared by melt quenching method. The spectroscopic and structural properties were characterized by X-ray diffraction, optical absorption, photoluminescence and solid state 31P NMR techniques. Optical properties were characterized through optical absorption and emission spectra using Judd-Ofelt (J-O) theory. The J-O parameters were used to characterize the absorption and luminescence spectra of these glasses. From the theory, radiative properties like radiative transition probabilities (AR), branching ratios (βR) and radiative lifetimes (τR) of certain excited states have been evaluated for the fluorescent levels of Er3+ in these glasses matrices. The emission spectra in the NIR region show one transition i.e. 4I13/2→4I15/2 which is more intense. For this transition effective bandwidths (∆ν) and emission cross sections (σp) have been evaluated. The decay curve analysis has been done for obtaining the decay constants of Er3+ for 4I13/2 excited level in all the phosphate glasses. These results are compared with the literature and discussed. From the magnitudes of stimulated emission cross-sections and branching ratios certain glasses are suggested for laser applications.