Judd-Ofelt analysis of Er +3 activated lead free fluoro-tellurite glass

A series of lead free fluoro-tellurite glasses containing different concentration of Er ₂O ₃ were prepared and the optical properties of the best luminescent sample (1 g mol% of Er ₂O ₃) have been investigated by Judd-Ofelt theory to judge its suitability as practical photonic material. Three intensity parameters Ω ₂ = 4.935 × 10 ^-20 cm ², Ω ₄ = 3.148 × 10 ^-20 cm ², Ω ₆ = 1.745 × 10 ^-20 cm ² of the ion in the glass, were determined from the optical absorption data, which were used to calculate the parameters like the radiative transition probabilities ( A_r), radiative life-times ( τ_f), fluorescence branching ratios ( β_c) and the integrated emission cross-section ( Σσ) of its different transitions. Experimental optical absorption intensity and the calculated values of oscillator strength (P), suggested that the Er ⁺³ ions in the glass can most effectively be excited by ⁴I _15/2 → ⁴G _11/2 (376 nm), ⁴I _15/2 → ⁴F _7/2 (486 nm) and ⁴I _15/2 → ²H _11/2 (519 nm) transitions while calculated spontaneous emission rate ( A_r) values showed that strong visible emissions at 650 nm and 546 nm should occur, respectively, through ( ⁴F _9/2 → ⁴I _15/2) and ( ⁴S _3/2 → ⁴I _15/2) transitions and NIR emissions at 1532, 1222, 974 and 838 nm, respectively, through ( ⁴I _13/2 → ⁴I _15/2), ( ⁴S _3/2 → ⁴I _11/2), ( ⁴I _11/2 → ⁴I _15/2), and ( ⁴S _3/2 → ⁴I _13/2) transitions. The spectroscopic data indicate that the present glass is a prospective photonic material for practical applications in the visible and NIR region.