Preparation and spectroscopic properties of Er3+-doped high silica glass fabricated by sintering nanoporous glass

A compact nonporous high silica (SiO2 % > 96%) glass containing 3400 ppm Er3+ ions, which was about ten times higher than that in Er-doped silica fiber amplifier (EDSFA), was synthesized by sintering porous glass immersed into erbium nitrate solution. The 1532 nm fluorescence has a FWHM (Full Width at Half Maximum) of 45 nm wider than that of EDSFA and possesses the glass with potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that Er3+ ions are located in a higher covalent environment which are comparable to those of aluminosilicate glass. (c) 2005 Elsevier B.V. All rights reserved.

Spectroscopic properties of neodymium doped high silica glass and aluminum codoping effects on the enhancement of fluorescence emission

Nd3+ -codoped and Al3+-Nd3+-codoped high silica glasses have been prepared by sintering nanoporous glasses impregnated with Nd3+ stop and Al3+ ions. The Judd-Ofelt intensity parameters Omega(2,4,6) of Nd3+-doped high silica glasses were obtained and used to analyze aluminum codoping effects. Fluorescence properties of Nd3+-doped high silica glasses strongly depend on the Al3+ concentration. While Nd3+ ion absorption and emission intensities of obviously increase when aluminum is added to Nd3+-doped high silica glasses, fluorescence lifetimes decrease and aluminum codoping has almost no influence on the radiative quantum efficiencies. This indicates that aluminum codoping is responsible for an anti-quenching effect through a local modification of rare-earth environments rather than through physical cluster dispersion.

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.

Spectroscopic properties of Nd3+-doped high silica glass prepared by sintering porous glass

A new kind of Nd3+, -doped high silica glass (SiO2 > 96% (mass fraction)) was obtained by sintering porous glass impregnated with Nd3+, ions. The absorption and luminescence properties of high silica glass doped with different Nd3+, concentrations were studied. The intensity parameters Omega(t) (t = 2, 4, 6), spontaneous emission probability, fluorescence lifetime, radiative quantum efficiency, fluorescence branching ratio, and stimulated emission cross section were calculated using the Judd-Ofelt theory. The optimal Nd3+ concentration in high silica glass was 0.27% (mole fraction) because of its high quantum efficiency and emission intensity. By comparing the spectroscopic parameters with other Nd3+ doped oxide glasses and commercial silicate glasses, the Nd3+-doped high silica glasses are likely to be a promising material used for high power and high repetition rate lasers.

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.

High quantum efficiency and high concentration erbium-doped silica glasses fabricated by sintering nanoporous glasses

A new method was used to prepare erbium-doped high silica (SiO2% > 96%) glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in silica glasses prepared by using conventional methods. The fluorescence of 1532 nm has an FWHM (Full Wave at Half Maximum) of 50 nm, wider than 35 nm of EDSFA (erbium-doped silica fiber amplifer), and hence the glass possesses potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that the quantum efficiency of this erbium-doped glass is about 0.78, although the erbium concentration in this glass (6 x 103) is about twenty times higher than that in silica glass. These excellent characteristics of Er-doped high silica glass will be conducive to its usage in optical amplifiers and microchip lasers.

Spectroscopic properties and thermal stability of Er3+-doped tungsten-tellurite glass for waveguide amplifier application

Tungsten-tellurite glass with molar composition of 60TeO(2)-30WO(3)-10Na(2)O has been investigated for developing planar broadband waveguide amplifier application. Spectroscopic properties and thermal stability of Er3+-doped tungsten-tellurite glass have been discussed. The results show that the introduction Of WO3 increases significantly the glass transition temperature and the maximum phonon energy. Er3+-doped tungsten-tellurite glass exhibits high glass transition temperature (377 degrees C), large emission cross-section (0.91 x 10(-20) cm(2)) at 1532 nm and broad full width at half maximum (FWHM), which make it preferable for broadband Er3+-doped waveguide amplifier application. (c) 2005 Elsevier B.V. All rights reserved.

Preparation and spectroscopic properties of Yb-doped and Yb-Al-codoped high silica glasses

Yb-doped and Yb-Al-codoped high silica glasses have been prepared by sintering nanoporous glasses. The absorption, fluorescent spectra and fluorescent lifetimes have been measured and the emission cross-section and minimum pump intensities were calculated. Codoping aluminum ions enhanced the fluorescence intensity of Yb-doped high silica glass obviously. The emission cross-sections of Yb-doped and Yb-Al-codoped high silica glasses were 0.65 and 0.82 pm(2), respectively. The results show that Yb-Al-codoped high silica glass has better spectroscopic properties for a laser material. The study of high silica glass doped with ytterbium is helpful for its application in Yb laser systems, especially for high-power and high-repetition lasers. (C) 2007 Elsevier B.V. All rights reserved.

New transparent Er3+-doped oxyfluoride tellurite glass ceramic with improved near infrared and up-conversion fluorescence properties

Transparent glass ceramics have been obtained by nucleation and growth of Y2Te6O15 or Er2Te5O13 cubic phase in a new Er3+-doped oxyfluoride tellurite glass. Effect of beat treatment on absorption spectra, luminescence and up-conversion properties in the oxyfluoride tellurite glass has been investigated. With heat treatment the ultraviolet absorption edge red shifted evidently for the oxyfluoride telluride glass. The near infrared emission that corresponds to Er3+:I-4(13/2)-> I-4(15/2) can be significantly enhanced after heat treatment. Under 980 nm LD pumping, red and green up-conversion intensity of Er3+ in the glass ceramic can be observed much stronger than that in the base glass. (C) 2006 Elsevier B.V. All rights reserved.

Host dependent frequency upconversion of Er3+-doped oxyfluoride germanate glass

Er3+-doped oxyfluoride germanate glasses have been synthesized by the conventional melting and quenching method. The Judd-Ofelt intensity parameters were calculated based on the Judd-Ofelt theory and absorption spectra measurements. With the substitution of PbF2 for PbO, the Omega(2) parameter decreases, while the Omega(6) parameter increases. These change trends indicate that fluoride anions come to coordinate erbium cations and the covalency of the Er-O bond decreases. Structural and thermal stability properties were obtained by Raman spectra and differential thermal analysis, indicating that PbF2 plays an important role in the formation of glass network and has an important influence on the maximum phonon energy and thermal stability of host glasses. 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. With increasing PbF2 content, the intensity of red (657nm) emissions increases significantly, while that of the green (525 and 546nm) emission increases slightly. The results indicate that PbF, has more influence on the red (657nm) emission than the green (525 and 546nm) emissions in oxyfluoride germanate glasses. The possible upconversion luminescence mechanisms have also been estimated and discussed. (c) 2005 Elsevier B.V. All rights reserved.

Frequency upconversion fluorescence emission of Er3+-doped oxychloride germanate glass

Frequency upconversion fluorescence property of Er3+-doped oxychloride germanate glass is investigated. Intense green and red emissions centred at 525, 546, and 657nm, corresponding to the transitions H-2(11/2) -> I-4(15/2), S-4(3/2) -> 4I(15/2), and F-4(9/2) -> I-4(15/2), respectively, were simultaneously 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 laser diode (LD) excitation. The Raman spectrum investigation indicates that oxychloride germanate glass has the maximum phonon energy at similar to 805 cm(-1). The thermal stability of this oxychloride germanate glass is evaluated by differential scanning calorimetry, and thermal stability factor Delta T (Delta T = T-x-T-g) is 187 degrees C. Intense upconversion luminescence and good thermal stability indicate that Er3+-doped oxychloride germanate glass is a promising upconversion laser material.

Spectral properties and stability of Er3+-doped TeO2-WO3 glass

Er3+-doped TeO2-WO3 glass was fabricated and characterized by absorption spectrum, fluorescence spectrum, Raman spectrum and stability. The Judd-Ofelt parameter ohm(t)(t = 2, 4, 6) were calculated from the absorption spectrum by the Judd-Ofelt theory. The fluorescence spectrum indicates that the fluorescence width at half-maximum (FWHM) is 66nm. The stimulated emission cross-section of Er3+ in TeO2-WO3 glass at 1532 nm was calculated to be 0.80 x 10(-20) cm(2) by McCumber theory. The phonon energy of TeO2-WO3 glass is found to be 931 cm(-1). The difference between crystallization onset temperature and glass transition temperature Delta T is 112 degrees C. These results show that Er3+-doped TeO2-WO3 glass has higher stability and good spectral properties, which were useful for broadband amplifier. (c) 2005 Elsevier B.V. All rights reserved.

Upconversion emission in Er3+ doped novel bismuthate glass

Novel Er3+-doped bismuth lead strontiam glass was fabricated and characterized, and the absorption spectrum and upconversion spectrum of the glass were studied. The Judd-Ofelt intensity parameters Omega(t)(t = 2, 4, 6) were found to be Omega(2) = 3.27 x 10(-20) cm(2), Omega(4) = 1.15 x 10(-20) cm(2), and Omega(6) = 0.38 x 10(-20) cm(2). The oscillator strength, the spontaneous transition probabilities, the fluorescence branching ratios, and excited state lifetimes were also measured and calculated. The upconversion emission intensity varies with the power of infrared excitation intensity. A plot of log I-up vs log I-IR yields a straight line with slope 1.86, 1.88 and 1.85, corresponding to 525, 546, and 657 nm emission bands, respectively, which indicates that a two-photon process for the red and green emission.