Spectral analysis and line strengths of Tm2O3 doped ZrF4-BaF2-LaF3-AlF3-NaF glass under upconversion excitation at a pumping wavelength of 1064 nm

Abstract

In the visible range at blue 455 nm, 482 nm, and red 670 nm under upconversion pumping at a wavelength of 1064 nm, spectroscopic characteristics, and transition rates in Tm3+ doped 0.53 ZrF4, 0.2 BaF2, 0.04 LaF3, and 0.03 AlF3 and 0.2 NaF (ZBLAN) glass matrix are described. The Judd-Ofelt theory is applied to calculate the contributions from electric and magnetic dipoles to the optical intensity parameters (Ωt), which are found to be as follows: Ω2 = 1.4703 ± 0.0675, Ω4 = 0.7477 ± 0.0536, Ω6 = 0.6202 ± 0.0212. For transitions originating from the 1D2, 1G4, 2F2, 3F3, and 3F4 levels, branching ratios (β), radiative lifetimes (τ rad in ms units), and transition probabilities (in s−1) have been calculated. Additionally, we evaluated the optical gain at 455 nm, 467 nm, and 670 nm, as well as the absorption/emission cross sections for the three visible transitions. According to the obtained results, the transition at 455 nm (1D2 → 3F4) had the largest emission cross section values compared to transitions at 482 nm (1G4 → 3H6) and 670 nm (3F2 → 3H6). Furthermore, the transition probability.is theoretically calculated for the ultraviolet (UV) range 172–283.8 nm. A good agreement is found between the calculations and the measurements for the visible range.