Glasses with composition 20B_(2)O_(3).(79.5-x)Bi_(2)O_(3).xSiO_(2) (10 ≤ x ≤ 40) containing 0.5mol% of Er~(3+) ions were prepared by melt-quench technique. Optical absorption and fluorescence spectra were recorded at room temperature for all glass samples. Based on the Judd-Offelt theory, spectroscopic properties of Er~(3+) ions are discussed by changing the host glass compositions. The intensity parameters Ω_(2), Ω_(4), and Ω_(6) are determined by applying least square analysis method. The variation of Ω_(2) and Ω_(6) with Bi_(2)O_(3) content has been attributed to changes in the asymmetry of the ligand field at the rare earth ion site and to the changes in the rare earth oxygen (RE-O) covalency. The variation of Ω_(4) with Bi_(2)O_(3) content has been attributed to rigidity of the samples. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross-section of various emission lines have been evaluated. An intense green luminescence bands with maximum around 516 nm and 536 nm are assigned to the ~(2)H_(11/2)→ ~(4)I_(15/2) and ~(4)S_(3/2)→ _(4)I_(15/2) transitions respectively has been obtained.
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