Excitation and luminescence of rare earth-doped lead phosphate glasses

Excitation and luminescence properties of Eu3+, Tb3+ and Er3+ ions in lead phosphate glasses have been studied. From excitation spectra of Eu3+ ions, the electron–phonon coupling strength and phonon energy of the glass host were calculated and compared to that obtained by Raman spectroscopy. Main intense and long-lived luminescence bands are related to the 5D0–7F2 (red) transition of Eu3+, the 5D4–7F5 (green) transition of Tb3+ and the 4I13/2–4I15/2 (near-infrared) transition of Er3+. The critical transfer distances, the donor–acceptor interaction parameters and the energy transfer probabilities were calculated using the fitting of the luminescence decay curves from 5D0 (Eu3+), 5D4 (Tb3+) and 4I13/2 (Er3+) excited states. The energy transfer probabilities for Eu3+ (5D0), Tb3+ (5D4) and Er3+ (4I13/2) are relatively small, which indicates low self-quenching luminescence of rare earth ions in lead phosphate glasses

Laser transition characteristics of Nd3+-doped fluorophosphate laser glasses

Fluorophosphate glasses of composition P2O5-K2O-MgO)-A1(2)O(3)-A1F(3) and P2O5-K2O-MgO-A1(2)O(3)-BaF2 were prepared with different Nd3+ ion concentrations. The absorption and emission spectra in the UV-VIS-NIR region were measured for these glasses. Judd-Ofelt analysis has been carried out using the absorption spectra of 1.0 mol% Nd3+-doped glasses to evaluate the radiative properties for some luminescent levels of the Nd3+ ion. The stimulated emission cross-sections of the F-4(3/2) -> I-4(11/2) laser transition for the present glasses are found to be higher than for other Nd3+-doped glasses. Branching ratio calculations also revealed the potentiality of the F-4(3/2) I-4(11/2) transition for laser action in these glasses. The observed concentration quenching of the lifetime of the 4 F3/2 level is explained as a result of cross-relaxation process between the Nd3+ ions

Luminescence characteristics of Nd3+ - doped K-Ba-Al-fluorophosphate laser glasses

Fluorophosphate glasses of composition P2O5 + K2O + KF + BaO + Al2O3 + Nd2O3 (PKFBAN), have been prepared with three (0.1, 1.0 and 2.0 mol%) Nd3+ ion concentrations and their detailed luminescence properties have been investigated. Judd-Ofelt theory has been used to analyse the optical absorption spectrum of 1.0 mol% Nd2O3-doped PKFBAN glass and evaluated the radiative properties. The predicted radiative lifetime of the F-4(3/2) level is found to be 348 mu s, which is slightly larger than the measured lifetime of 286 mu s. The measured lifetime of the F-4(3/2) level is found to decrease from 359 to 227 lis when the Nd2O3 ions concentration is increased from 0.1 to 2.0 mol%. The observed non-exponential nature of the decay curves is attributed to energy transfer between Nd3+ ions through dipole-dipole interaction. The systematic analysis yielded improved laser properties in K-Ba-Al-fluorophosphate glass with respect to those of K-Ba-Al-phosphate glasses

Composition and concentration dependence of spectroscopic properties of Nd3+-doped tellurite and metaborate glasses

The spectroscopic properties of tellurite glasses of composition (in mol%) TNKNd: (70 - x)TeO2-15Nb(2)O(5)-15K(2)O-xNd(2)O(3) (x = 0.1, 1.0, 1.5, 2.0 and 2.5) and TNLNd10: 69TeO(2)-15Nb(2)O(5)-15Li(2)O-1.0Nd(2)O(3) and lithium metaborate glass of composition LBNNd10: 89LiBO(2)-10Nb(2)O(5)-1.0Nd(2)O(3) have been investigated using absorption and emission spectra and decay curve analysis. An energy level analysis has been carried out considering the experimental energy positions of the absorption and emission bands, using the free-ion Hamiltonian model. The spectral intensities have been calculated by using the Judd-Ofelt theory and in turn the radiative properties such as radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes have been estimated. The decay curves at the lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (>= 1.0 mol%) due to energy transfer processes. The effective lifetimes for the F-4(3/2) level are found to decrease with increase in Nd2O3 concentration for all the glasses under investigation. The non-exponential decay curves have been well-fitted to the Yokota-Tanimoto model with S = 6, indicating that the nature of energy transfer is of dipole-dipole type and energy migration also plays an important role. The results obtained have been compared with Nd3+-doped phosphate, fluorophosphate, lead borate, tellurite, germanate and silicate glasses and Nd3+-doped VAG ceramic and Ca2Nb2O7 crystals. (C) 2010 Elsevier B.V. All rights reserved