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.

Novel lithium-barium-lead-bismuth glasses

New lithium-barium-lead-bismuth glasses with low OH- concentration have been obtained. The role of the different components in the glass formation has been explored from the thermal, density, and refractive index measurements. The T-g, T-x, and T-x-T-g values of these glasses are in the range of 358-400, 453-575, and 87-197 degreesC, respectively. The densities (p) and refractive indices of these glasses are mainly affected by Bi2O3 and PbO contents. A wide transmitting window from visible to infrared (IR) regions for some compositions of these glasses has been observed, which makes them appealing candidates for different optical applications such as upconverting phosphors, new laser materials, optical waveguides, and crystal-free fibre drawing. (C) 2004 Elsevier B.V. All rights reserved.

Structural and upconversion fluorescence properties of Er3+/Yb3+-codoped oxychloride lead-germanium-bismuth glass

Structural and infrared-to-visible upconversion fluorescence properties of Er3+/Yb3+-codoped oxychloride lead-germanium-bismuth glass have been studied. The Raman spectrum investigation indicates that PbCl2 plays an important role in the formation of glass network, and has an important influence on the upconversion luminescence owing to lower phonon energy. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions H-2(11/2)-->I-4(15/2,) I-4(3/2)-->I-4(15/2), and F-4(9/2)-->I-4(15/2), respectively, were observed at room temperature. 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. (C) 2004 Elsevier Ltd. All rights reserved.

Structural and up-conversion luminescence properties in Tm (3+)/Yb3+-codoped heavy metal oxide-halide glasses

Tm3+/Yb3+-codoped heavy metal oxide-halide glasses have been synthesized by conventional melting and quenching method. Structural properties were obtained based on the Raman spectra, indicating that halide ion has an important influence on the phonon density and maximum phonon energy of host glasses. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions (1)G(4) -> H-3(6) and (1)G(4) -> H-3(4), respectively, were observed at room temperature. The possible up-conversion mechanisms are discussed and estimated. With increasing halide content, the up-conversion luminescence intensity and blue luminescence lifetimes of Tm3+ ion increase notably. Our results show that with the substitution of halide ion for oxygen ion, the decrease of phonon density and maximum phonon energy of host glasses both contribute to the enhanced up-conversion emissions. (c) 2005 Elsevier B.V. All rights reserved.

Upconversion properties of TM3+/Yb3+ codoped fluorophosphate glasses with low phonon density of states

Fluorophosphate glasses codoped with Tm3+ and Yb3+ were prepared and their thermal stability, phonon states, and upconversion properties were studied. It is found that the increment of phosphate content is good for the thermal stability but increases the phonon density of states. However, the phonon density of states of these fluorophosphate glasses is very low due to the low phosphate content in their composition. The upconversion luminescence spectra were measured under excitation of 970 nm laser diode, and the intense blue (476 nm) and near infrared (794 nm) emission were simultaneous obtained at room temperature. The sensitizing mechanisms of Yb3+ to Tm3+ for blue and red emission contain both sequential and cooperative sensitization. The near infrared emission is a two-photon upconversion process. These researches suggest that when the phosphate content in the composition is low enough, fluorophosphate glass can be suitable host material of Tm3+ codoped with Yb3+ for blue and near infrared upconversion luminescence. (c) 2005 Elsevier B.V All rights reserved.

Comparative investigation of up-conversion luminescence in Tm3+/Yb3+-codoped germanate-niobic and germanium-bismuth glasses: effect of phonon density on up-conversion emission

Tm3+/Yb3+-codoped gernianate-niobic (GN) and germanium-bismuth (GB) glasses have been synthesized by conventional ruching and quenching method. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions (1)G(4)->H-3(6) and (1)G(4)->H-3(4), respectively, were observed at room temperature. The possible Up-conversion mechanisms are discussed and estimated. GN glass showed a weaker up-conversion emission than GB glass, which is inconsistent with the prediction from the difference of maximum phonon energy between GN and GB glasses. In this paper, Raman spectroscopy was employed to investigate the origin of the difference in up-conversion luminescence in the two glasses. Compared with phonon side-band spectroscopy, Raman spectroscopy extracts more information including both phonon energy and phonon density. For the first time, our results reveal that, besides the maximum phonon energy, the phonon density of host glasses is also an important factor in determining the up-conversion efficiency. (c) 2005 Elsevier Ltd. All rights reserved.

Comparative investigation of up-conversion luminescence in Tm3+-doped oxide-chloride germanate and tellurite glasses

Tm3+-doped oxide-chloride germanate and tellurite glasses have been synthesized by conventional melting method. Intense up-conversion luminescence emissions were simultaneously observed at room temperature in these glasses. The possible up-conversion mechanisms are discussed and estimated. However, in these Tm3+-doped glasses, tellurite glass showed weaker up-conversion emissions than germanate glass, which is inconsistent with the prediction from the difference of maximum phonon energy between tellurite and germanate glasses. In this paper, Raman spectroscopy was employed to investigate the origin of the difference in up-conversion luminescence in the two glasses. Our results confirm that, besides the maximum phonon energy, the phonon density of host glasses is also an important factor in determining the up-conversion efficiency. (c) 2005 Elsevier Ltd. All rights reserved.

Up-conversion luminescence analysis in ytterbium-sensitized erbium-doped oxide-halide tellurite and germanate-niobic-lead glasses

Ytterbium-sensitized erbium-doped oxide-halide tellurite and germanate-niobic-lead glasses have been synthesized by conventional melting method. Intense green and red emissions centered at 525, 546 and 657 nm, 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 simultaneously observed at room temperature in these glasses. The quadratic dependence of the 525, 546 and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs. Tellurite glass showed a weaker up-conversion emission than germanate-niobic-lead glass, which is inconsistent with the prediction from the difference of maximum phonon energy between tellurite and germanate-mobic-lead glasses. In this paper, Raman spectroscopy was employed to investigate the origin of the difference in up-conversion luminescence in the two glasses. Compared with phonon side-band spectroscopy, Raman spectroscopy extracts more information including both phonon energy and phonon density. Our results reveal that the phonon density and the maximum phonon energy of host glasses are both important factors in determining the up-conversion efficiency. (c) 2005 Elsevier B.V. All rights reserved.

Intense upconversion luminescence in ytterbium-sensitized thullum-doped oxychloride germanate glass

Structural and upconversion fluorescence properties in ytterbium-sensitized thulium-doped oxychloride germanate glass have been studied. The structure of oxychloride germanate glass was investigated by peak-deconvolution of Raman spectrum, and the structural information was obtained from the peak wavenumbers. The Raman spectrum investigation indicates that PbCl2 plays an important role in the formation of glass network, and has an important influence on the upconversion luminescence. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions (1)G(4) ->(3) H-6 and (1)G ->H-3(4), respectively, were observed at room temperature. The possible upconversion mechanisms are discussed and estimated. Intense upconversion luminescence indicates that oxychloride germanate glass can be used as potential host material for upconversion lasers. (c) 2004 Elsevier B.V. All rights reserved.

Effect of F- ions on spectroscopic properties of Yb3+-doped zinc-tellurite glasses

this paper is retracted

Effect of bismuth oxide introduction on spectroscopic properties of Er3+/Yb3+ co-doped aluminophosphate glasses

The absorption spectra, emission spectra and infrared spectra of Er3+/Yb3+ co-doped xBi(2)O(3)-(65 - x)P2O5-4Yb(2)O(3)-11Al(2)O(3)-5BaO-15Na(2)O were measured and investigated. Spontaneous emission probability, radiative lifetime and branching ratios of Er3+ were calculated according to the Judd-Ofelt theory. The role of substitution of Bi2O3 for P2O5 on luminescence of Er3+/Yb3+ co-doped aluminophosphate glasses has been investigated. The calculated radiative lifetimes (tau(rad)) for I-4(13/2) and I-4(11/2) were decreasing with Bi2O3 content increases, whereas the measured total lifetime (tau(meas)) for I-4(13/2) showed linearly increasing trends. The effect of Bi2O3 introduction on OH- groups was also discussed according to the IR transmittance spectra of glasses. It was found that FWHM of glasses were not affected with the substitution of Bi2O3 for P2O5. The emission spectra intensity increased with Bi2O3 content due to the decreases of phonon energy and OH- content in glasses. (C) 2007 Elsevier B.V. All rights reserved.

Effects of chloride substitution on the chemical and physical properties and the crystallization behavior in heavy metal fluoride glasses

Effect of the substitutions of chloride for fluoride on the chemical and physical properties and the crystallization behavior in heavy metal fluoride glasses has been investigated. The characteristic temperature of the glass does not changed obviously when the fluoride was taken place by chloride. Compared with samples of being free of ErF3, the doping samples are more inclined to be surface crystallization. Optical basicity in the glass system increases with increasing the negative charge provided by the chloride atoms and the absorption peak red shifted is observed in absorption spectra. XRD measurements show that not a single crystalline phase appears in the heated glass samples, which indicate the substitutions of chloride for fluoride with a variety of crystalline precipitation trends. (c) 2007 Elsevier B.V All rights reserved.

Luminescence properties of bismuth-doped lime silicate glasses

Luminescences from bismuth-doped lime silicate glasses were investigated. Luminescences centered at about 400, 650, and 1300 nm were observed, excited at 280, 532 and 808 nm, respectively. These three luminescence bands arise from three different kinds of bismuth ions in the glasses. The visible luminescences centered at 400 and 650 nm arise from Bi3+, and Bi2+, respectively. The infrared luminescences cover the wavelength range from 1000 to 1600 nm when exited by an 808 nm laser diode. The full width at half maximum (FWHM) of the infrared luminescences is more than 205 urn. The intensity of the infrared luminescence decreases with the increment in CaO content. We suggest that the infrared luminescences might arise from Bi+. Such broadband luminescences indicate that the glasses may be potential candidate material for broadband fiber amplifiers and tunable lasers. (C) 2007 Elsevier B.V. All rights reserved.