Spectroscopic Properties of TmF[sub.3]-Doped CaF[sub.2] Crystals

In this study, we report the growth and comprehensive spectroscopic analysis of TmF[sub.3]-doped CaF[sub.2] crystals, grown using the vertical Bridgman method. The optical absorption and photoluminescence properties of both trivalent (Tm[sup.3+]) and divalent (Tm[sup.2+]) thulium ions were investigated. Optical absorption spectra in the UV-VIS-NIR range reveal characteristic transitions of Tm[sup.3+] ions, as well as weaker absorption bands corresponding to Tm[sup.2+] ions. The Judd–Ofelt (JO) formalism was applied to determine the intensity parameters Ω[sub.2], Ω[sub.4], and Ω[sub.6], which were used to calculate radiative transition probabilities, branching ratios, and radiative lifetimes for the Tm[sup.3+] ions. The emission spectra showed concentration-dependent quenching effects, with significant emissions observed for the concentration of 0.1 mol% TmF[sub.3] under excitation at 260 nm and 353 nm for Tm[sup.3] [sup.+] ions and at 305 nm for Tm[sup.2+] ions. A new UV emission associated with divalent Thulium is reported. The results indicate that higher TmF[sub.3] concentrations lead to increased non-radiative energy transfer, which reduces luminescence efficiency. These findings contribute to the understanding of the optical behavior of Tm-doped fluoride crystals, with implications for their application in laser technologies and radiation dosimetry.