Optical Transitions and Excited State Absorption Cross Sections of SrLaGaO4 Doped with Ho3+ Ions

The spectroscopic properties of SrLaGaO4 (SLO) crystal doped with Ho3+ ions were studied in this work. Absorption, emission spectra and decay dynamics of excited states have been measured and discussed using the Judd–Ofelt model. Photoluminescence emissions were attributed to transitions from the excited 3D3, 5S2, 5F5, 5I6 and 5I7 multiplet manifolds. The experimental lifetimes for five excited states have been compared to the theoretical values, calculated using Judd–Ofelt theory, allowing for the determination of the multiphonon relaxation rates (WnR) of the respective states. The experimental data were approximately on a line expressed by WnR = W0 exp(−αΔE) with W0 = 0.5 × 107 s−1 and α = 2.6 × 10−3 cm. To discuss the excited state absorption (ESA) pathways, that originated from several excited levels, we used the Judd–Ofelt formalism allowing determination of the integrated cross section for ESA transitions.

Higher Intrinsic Quantum Yield of Eu3+-Doped Zn2sio4 Obtained by Sol-Gel Process, Calculated by Judd - Ofelt Theory

The sol-gel process allows the obtaining of Eu3+-doped Zn2SiO4with 1 mol% with different molar ratios between Zn2+ and Si4+. The materials reported here were obtained with a resistive furnace at 600, 900, 1000 and 1100°C degree, during 2 h. All the materials exhibited an intense photoluminescence emission with bands assigned to the Eu3+ transitions. Among the materials studied, the samples containing 70 and 80% of Si4+, exhibited higher Eu3+ lifetimes values. The predominance of the quartz phase decreases micro deformations and the location of the Eu3+ ions in higher symmetry sites, reducing the intensity of the photoluminescent materials. The increasing of annealing temperature contributes to the detrimental lifetime and luminescence materials due to the location of the Eu3+ in the site of high symmetry. Through Judd-Ofelt theory was possible to obtain higher values of intrinsic quantum yield (QLn Ln) between 32 and 66% dependent on the temperature of heat-treatment, in comparison with the same material reported in the literature. Keywords: Orthosilicates; Photoluminescence; Rare Earth; Europium;

Влияние концентрации фосфатов на спектральные свойства ионов тулия во фторфосфатных стеклах

The Jadd-Ofelt parameters for thulium ions in fluorophosphate glasses with different phosphate content are calculated. The proximity of the values of the parameters Ωt of glasses with a content of up to 10 mol% Ba(PO3)2 to the similar parameters of the fluoride glasses and a sharp increase in their values with a further increase in phosphates are shown. In the framework of the Jadd-Ofelt theory, the spectral-luminescent parameters of glasses are analyzed. The spontaneous transitions probabilities, branching coefficients (β), and radiation lifetimes (τrad) for various excited states of Tm3+ ions are obtained. It was found that, at low phosphate concentrations, glasses have a high radiation lifetime for the excited 3F4 laser level. It has been shown that the glasses with a content of up to 10 mol% Ba(PO3)2 are characterized by a wide flat gain spectrum, which makes them promising materials for creating broadband amplifiers.