Upconversion fluorescence property of Er3+/Yb3+-codoped novel bismuth-germanium glass

Infrared-to-visible upconversion fluorescence property of Er3+/Yb3+ codoped novel bismuth-germanium glass under 975 nm LD excitation has been studied. 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 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. The structure of the bismuth-germanium glass has been investigated by peak-deconvolution of FT-Raman spectrum, and the structural information was obtained from the peak wavenumbers. This novel bismuth-germanium glass with low maximum phonon energy (similar to 750 cm(-1)) can be used as potential host material for upconversion lasers. (c) 2005 Elsevier Ltd. All rights reserved.

Intense upconversion luminescence in ytterbium-sensitized thulium-doped novel oxychloride bismuth-germanium glass

Structural and up-conversion fluorescence properties in ytterbium-sensitized thulium-doped novel oxychloride bismuth-germanium glass have been studied. The structure of novel bismuth-germanium glass was investigated by peak-deconvolution of Raman spectrum, and the structural information was obtained from the peak wave numbers. The Raman spectrum investigation indicates that PbCl2 plays an important role in the formation of glass network, and has an important influence on the up-conversion luminescence. Intense blue and weak red emissions centered at 477 and 650 mn, corresponding to the transitions 1G(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. This novel oxychloride bismuth-germanium glass with low maximum phonon energy (similar to 730 cm(-1)) can be used as potential host material for up-conversion lasers. (c) 2005 Elsevier Ltd. All rights reserved.

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

We study the structural and infrared-to-visible upconversion fluorescence properties of Er3(+)/Yb3+-codoped lead-free germanium-bismuth glass. The structure of lead-free germanium-bismuth-lanthanum glass is investigated by peak-deconvolution of Raman spectroscopy. Intense green and red emissions centred at 525, 546, and 657nm, corresponding to the transitions H-2(11/2) -> (IT15/2)-I-4 -> S-4(3/2) -> 4I(15/2), and F-4(9/2) -> I-4(15/2), respectively, are observed at room temperature. The quadratic dependence of the 525, 546, and 657nm emissions on excitation power indicates that a two-photon absorption process occurs under 975nm excitation.

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.

Optical transitions of Er3+ and Yb3+ ions in novel oxyfluoride bismuth-germanium glass: Observation of up-conversion

Er3+/Yb3+-codoped novel oxyfluoride bismuth-germanium glass was prepared and its up-conversion fluorescence property under 975 nm excitation has been studied. Intense green and weak red emissions centered at 525, 546, and 657 nm, corresponding to the transitions 2H(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 at room temperature. The possible up-conversion mechanism was also evaluated. The optimal Yb3+-Er3+ concentration ratio is found based on the direct lifetime measurements of excited levels for Er3+ ion. The structure of this novel oxyfluoride bismuth-germanium glass has been investigated by peak-deconvolution of FT-Raman spectrum, and the structural information was obtained from the peak wavenumbers. This novel oxyfluoride bismuth-germanium glass with relatively lower maximum phonon energy (similar to 731 cm(-1)) can be used as potential host material for up-conversion lasers. (c) 2005 Elsevier B.V. All rights reserved.

Transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics with broadband infrared luminescence

We report on transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics with broadband infrared luminescence. Ni2+-doped MgO-Al2O3-SiO2 glass is Prepared by using the conventional method. After heat treatment at high temperature, MgAl2O4 crystallites are precipitated, and their average size is about 4.3nm. No luminescence is detected in the as-prepared glass sample, while broadband infrared luminescence centred at around 1315nm with full width at half maximum (FWHM) of about 300nm is observed from the glass ceramics. The observed infrared emission could be attributed to the T-3(2g)(F-3) -> (3)A(2g)(F-3) transition of octahedral Ni2+ ions in the MgAl2O4 crystallites of the transparent glass ceramics. The product of the fluorescence lifetime and the stimulated emission cross section is about 1.6 X 10(-24) s cm(2).

Concentration quenching in erbium-doped tellurite glasses

Er2O3-doped TeO2-ZnO-La2O3 modified tellurite glasses were prepared by the conventional melt-quenching method, and the Er3+ : I-4(13/2) -> I-4(15/2) fluorescence properties have been studied for different Er3+ concentrations. Infrared spectra were measured in order to estimate the exact content of OH- groups in samples. Based on the electric dipole-dipole interaction theory, the interaction parameter, C-Er,(Er), for the migration rate of Er3+ : I-4(13/2) -> I-4(13/2) in modified tellurite glass was calculated. Finally, the concentration quenching mechanism using a model based on energy transfer and quenching by hydroxyl (OH-) groups was presented. (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.

Spectroscopic and fluorescence decay behaviors of Yb3+ -doped SiO2-PbO-Na2O-K2O glass

The spectroscopic and fluorescent decay behaviors of Yb3+-doped SiO2-PbO-Na2O-K2O glass is reported in this work. Yb2O3 contents of 1, 1.5 and 2mol% are added into the glass. Through the measurement of absorption and fluorescence spectra, and fluorescent decay rate at room temperature and at low temperature (18 K), it is found that the nonradiative decay rate of Yb3+ ions is mainly determined by the interaction between residual hydroxyl groups and Yb3+ ions. Concentration quenching effect can be omitted in this glass up to the Yb3+ ion concentration of 8.98 x 10(20)/cm(3). Multiphonon decay rate is also very small because of the large energy gap between F-2(5/2) and F-2(7/2) levels of Yb3+ ions. (c) 2004 Elsevier B.V. All rights reserved.

Energy transfer between Cr3+ and Ni2+ in transparent silicate glass ceramics containing Cr3+/Ni2+ co-doped ZnAl2O4 nanocrystals

The emission intensity of Ni2+ at 1200 nm in transparent ZnO-Al2O3-SiO2 glass ceramics containing ZnAl2O4 nanocrystals is improved approximately 8 times by Cr3+ codoping with 532 nm excitation. This enhanced emission could be attributed to an efficient energy transfer from Cr3+ to Ni2+, which is confirmed by time-resolved emission spectra. The energy transfer efficiency is estimated to be 57% and the energy transfer mechanism is also discussed. (C) 2008 Optical Society of America.

Enhanced broadband near-infrared luminescence in transparent silicate glass ceramics containing Yb3+ ions and Ni2+-doped Li Ga5 O8 nanocrystals

Spectral properties of Yb3+/Ni2+ codoped transparent silicate glass ceramics containing LiGa5O8 nanocrystals were investigated. The near-infrared emission intensity of Ni2+ was largely increased with Yb3+ codoping due to Yb3+-> Ni2+ energy transfer. The qualitative calculation of the energy transfer constant Cs-a and rate Ps-a showed that the Yb3+-> Ni2+ energy transfer was much greater than in the opposite direction. Yb3+/Ni2+ codoped glass ceramics with 0.75 mol % Yb2O3 exhibited a near-infrared emission with full width at half maximum of 290 nm and fluorescent lifetime of 920 mu s. The glass ceramics are promising for broadband optical amplification.

Inhomogeneous broadening, luminescence origin and optical amplification in bismuth-doped glass

Absorption and luminescence spectra and optical amplification in bismuth-doped germanate silicate glass were investigated. Two kinds of bismuth ion valence states could exist in the glass. One is Bi2+, which has shown red luminescence, another might be Bi+, which is the active center for infrared luminescence. The infrared luminescence excited at 700, 800, and 980 nm should be ascribed to the electronic transition P-3(1) --> P-3(0) of Bi+ ions in three distinct sites. The shifting, broadening, and multiple configuration of the luminescence could be due to the randomly disorder of local environment and multiple sites of the active centers. In this glass, obvious optical amplification was realized at 1300 nm wavelength when excited at 808 and 980 nm, respectively.

Fluorescence properties and laser demonstrations of Nd-doped high silica glasses prepared by sintering nanoporous glass

Porous glass with high-SiO2 content was impregnated with Nd ions, and subsequently sintered at 1100 degrees C into a compact non-porous glass in air or reducing atmosphere. Sintering in a reducing atmosphere produced an intense violet-blue fluorescence at 394 nm. However, the sintering atmospheres almost did not affect the fluorescence properties in the infrared range. A good performance Nd3+-doped silica microchip laser operating at 1064 nm was demonstrated. The Nd-doped sintering glasses with high-SiO2 content are potential host materials for high power solid-state lasers and new transparent fluorescence materials. (c) 2007 Elsevier B.V. All rights reserved.

Blue emission from Eu2+ -doped high silica glass by near-infrared femtosecond laser irradiation

Eu2+-doped high silica glass (HSG) is fabricated by sintering porous glass which is impregnated with europium ions. Eu2+-doped HSG is revealed to yield intense blue emission excited by ultraviolet (UV) light and near-infrared femtosecond laser. The emission profile obtained by UV excitation can be well traced by near-infrared femtosecond laser. The upconversion emission excited by 800 nm femtosecond laser is considered to be related to a two-photon absorption process from the relationship between the integrated intensity and the pump power. A tentative scheme of upconverted blue emission from Eu2+-doped HSG was also proposed. The HSG materials presented herein are expected to find applications in high density optical storage and three-dimensional color displays. (c) 2008 American Institute of Physics.