Effect of lithium-potassium mixed alkali on spectroscopic properties of Er3+-doped aluminophosphate glasses

Er3+-doped lithium-potassium mixed alkali aluminophosphate glasses belonging to the oxide system xK(2)O-(15x)Li2O-4B(2)O(3)-11Al(2)O(3)-5BaO-65P(2)O(5) are obtained in a semi-continuous melting quenching process. Spectroscopic properties of Er3+-doped glass matrix have been analysed by fitting the experimental data with the standard Judd-Ofelt theory. It is observed that Judd-Ofelt intensity parameters-Omega(t)(t=2, 4 and 6) of Er3+ change when the second alkali is introduced into glass matrix. The variation of line strength S-ed[I-4(13/2),I-4(15/2)] follows the same trend as that of the Omega(6) parameter. The effect of mixed alkali on the spectroscopic properties of the aluminophosphate glasses, such as absorption cross-section, stimulated emission cross-section, spontaneous emission probability, branching ratio and the radiative lifetime, has also been investigated in this paper.

Intense frequency upconversion fluorescence of Er3+/Yb3+-codoped novel potassium-barium-strontium-lead-bismuth glasses

Er3+/Yb3+-codoped potassium-barium-strontium-lead-bismuth glasses for developing potential upconversion lasers have been fabricated and characterized. Based on the results of energy transfer efficiency, the optimal Yb3+/Er3+ concentration ratio is found to be 5:1. Intense green and red emissions centered at 525, 546, and 657 run, corresponding to the transitions H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), and F-4(9/2) -> I-4(15/2), respectively, were observed. The quadratic dependence of the 525, 546, and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs under 975 nm excitation. The long-lived I-4(11/2) level is supposed to serve as the intermediate state responsible for the upconversion processes. (c) 2004 Elsevier B.V. All rights reserved.

Effect of lithium-sodium mixed-alkali on phase transformation kinetics in Er3+/Yb3+ co-doped aluminophosphate glasses

Er3+ doped aluminophosphate glasses with various Na2O/Li2O ratios were prepared at 1250 degrees C using a silica crucible to study mixed alkali effect (MAE). The effect of relative alkali content on glass transition temperature, crystallization temperature and thermal stability were investigated using differential scanning calorimetry (DSC). In addition, apparent activation energies for crystallization, E, were determined employing the Kissinger equation. The effect of Al2O3 content on the magnitude of MAE was also discussed. No mixed-alkali effect is observed on crystallization temperature. (c) 2006 Elsevier B.V. All rights reserved.

Influence of phosphate precursors on the structures of sodium aluminophosphate sols, gels and glasses

Transparent and homogeneous aluminophosphate gels and glasses have been widely synthesized through an aqueous sol-gel route, extending significantly the glass-forming range compared to that accessible via the melt-cooling route. Different phosphorus precursors, sodium polyphosphate (NaPO3) and orthophosphate species (NaH2PO4 and/or H3PO4) were compared with regard to the macroscopic properties and the microscopic structure of the resultant gels and glasses as characterized by extensive high-resolution liquid- and solid-state NMR. Sodium polyphosphate solution results in a substantially wider composition range of homogenous gel formation than orthophosphate solutions, and the two routes produce significant structural differences in the sol and xerogel states. Nevertheless, the structures of the glasses obtained upon gel annealing above 400 degrees C are independent of the P-precursors used. (c) 2007 Elsevier B.V. All rights reserved.

Broadband near-infrared emission from transparent Ni2+-doped sodium aluminosilicate glass ceramics

Broadband neat-infrared emission from transparent Ni2+-doped sodium aluminosilicate glass-cermaics is observed. The broad emission is centered at 1290 nm and covers the whole telecommunication wavelength region (1100-1700 nm) with full width at half maximum of about 340 nm. The observed infrared emission could be attributed to the T-3(2)(F) -> (3)A(2)(F) transition of octahedral Ni2+ ions that occupy high-field sites in nanocrystals. The product of the lifetime and the stimulated emission cross section is 2.15 x 10(-24) cm(2)s. It is suggested that Ni2+-doped sodium aluminosilicate glass ceramics have potential applications in tunable broadband light sources and broadband amplifiers.