Enhanced electronic transition probabilities and line intensities of Er + 3 ion in a (W, La)-tellurite glass as revealed from Judd–Ofelt analysis

Abstract

A series of tellurite glasses containing dispersed Er 2WO 6 nanocrystals of different concentration was prepared, and the optical properties of the best luminescent sample (1 g mol% of Er 2O 3) were investigated by Judd–Ofelt theory. The intensity parameters Ω 2 ( = 8.410 × 1 0 − 20 cm 2 ) , Ω 4 ( = 4.833 × 1 0 − 20 cm 2 ) , Ω 6 ( = 2.027 × 1 0 − 20 cm 2 ) of the Er +3 ion in the glass were determined and then used to calculate parameters such as the radiative transition probabilities ( A r ), radiative life-times ( τ f ), fluorescence branching ratios ( β c ) and the integrated emission cross-section ( Σ σ ) of different transitions. The experimental optical constant and the calculated oscillator strength values ( P ) suggest that the Er +3 ions in the glass can most effectively be excited by 4 I 15 / 2 → 4 F 7 / 2 (489 nm) and 4 I 15 / 2 → 2 H 11 / 2 (522 nm), 4 I 15 / 2 → 4 F 9 / 2 (653 nm) and 4 I 15 / 2 → 4 I 13 / 2 (1533 nm) transitions while the spontaneous emission rate ( A r ) values show that strong visible emissions should occur respectively through ( 4 F 9 / 2 → 4 I 15 / 2 ) and ( 4 S 3 / 2 → 4 I 15 / 2 ) transitions and strong NIR emissions through ( 4 I 13 / 2 → 4 I 15 / 2 ), ( 4 S 3 / 2 → 4 I 11 / 2 ), ( 4 F 9 / 2 → 4 I 13 / 2 ), ( 4 I 11 / 2 → 4 I 15 / 2 ), ( 4 S 3 / 2 → 4 I 13 / 2 ) transitions. The spectroscopic parameters show that the glass is a superior photonic material compared to other known Er +3 doped glass and crystals.