Spectroscopic properties and mechanism of Tm^3＋/Er^3＋/Yb^3＋ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals

Transparent Tm^3＋/Er^3＋/yb^3＋ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals are prepared. Under excitation of a 980-nm laser diode （LD）, compared with the glass before heat treatment, the Tm^3＋/Er^3＋/yb^3＋ co-doped oxyfluorogermanate glass ceramics can emit intense blue, green and red up-conversion luminescence and Stark- split peaks; X-ray diffraction （XRD） and transmission electron microscope （TEM） results show that BaF2 nanocrystals with an average diameter of 20 nm are precipitated from the glass matrix. Stark splitting of the up-conversion luminescence peaks in the glass ceramics indicates that Tm^3＋, Er^3＋ and （or） Yb^3＋ ions are incorporated into the BaF2 nanocrystals. The up-conversion luminescence intensities of Tm^3＋, Er^3＋ and the splitting degree of luminescence peaks in the glass ceramics increase significantly with the increase of heat treat temperature and heat treat time extension. In addition, the possible energy transfer process between rare earth ions and the up-conversion luminescence mechanism are also proposed.     

Research on upconversion codoped oxyfluoride luminescence in new Er^3＋/Yb^3＋ borosilicate glass ceramics

The upconversion luminescence of Er^3＋/Yb^3＋ ions is researched in a novel transparent oxyfluoride borosil- icate glass and glass ceramics under 980-nm excitation. Fluoride nanocrystals Ba2YF7 are successfully precipitated in glass matrix, which is affirmed by the X-ray diffraction results. Compared with the parent glasses, significant enhancement of upconversion luminescence is observed in the Er^3＋/Yb^3＋ codoped transparent glass-ceramics, which may be due to the variation of coordination environment around Er^3＋ and Yb^3＋ ions after crystallization. The possible upconversion mechanism is also discussed.     

Cooperative Quantum Cutting of Nano-Crystalline BaF2：Tb^3＋, Yb^3＋ in Oxyfluoride Glass Ceramics

We report on cooperative quantum cutting in Tb^3＋- Yb^3＋ codoped glass ceramics. Precipitation of BaF2 nanocrystals is confirmed by XRD and HRTEM analysis. Near-infrared emission due to transition of Yb^3＋ ions under 485 nm excitation indicates cooperative energy transfer from Tb^3＋ to Yb^3＋. The quantum efficiency of this process reaches 145%. The realization of quantum cutting in glass ceramics may have promising applications in solar cells.     

Upconversion Luminescence Dynamics in Er^3＋/Yb^3＋ Codoped Nanocrystalline Yttria

The upconversion luminescence and dynamics in Er^3＋ /Yb^3＋ codoped nanocrystalline yttria （7-65 nm） are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the green emission of ^2H11/2/^4S3/2 in nanoparticles with lower concentration of Yb^3＋ result from a two-photon excitation, In nanocrystals with higher Yb^3＋ concentration, the red emissions from a two-photon excitation, while the green emissions from a three-photon excitation, The luminescence dynamics indicates that as the particle size decreases, both the rise and the decay time constants become shorter, As the size decreases to several nanometres, the rise process nearly disappears, suggesting that the upconversion luminescence originates mainly from self-excitation of Er^3＋, instead of the energy transfer of Yb^3＋→ Er^3＋.     

Upconversion luminescence of Tm^3＋/Yb^3＋ codoped oxyfluoride glasses

Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - （4.9 - x） AlF3（x=0, 0.5, 1.0, 1.5, 2.0） in tool fraction, Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm^3＋： ^1D2 →^3F4, ^1G4 →^3H6, ^1G4 →^3F4, and ^3H4 →^3H6, respectively, are observed. Due to the sensitization of Yb^3＋ ions, all the upconversion luminescence intensities are enhanced considerably with Yb^3＋ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.     

White light generation of glass ceramics containing Ba_2LaF_7：Eu~（2＋）,Tb~（3＋） and Sm~（3＋） nanocrystals

The Eu 2＋ /Tb 3＋ /Sm 3＋ co-doped oxyfluoride glass ceramics containing Ba2LaF7 nanocrystals are prepared in the reducing atmosphere.The X-ray difiraction results show that Eu 2＋ ,Tb 3＋ and Sm 3＋ ions are enriched into the precipitated Ba2LaF7 nanophase after the annealing process.It deduces efficient energy transfers from Eu 2＋ to Tb 3＋ and Sm 3＋ and intenses warm white luminescence of the glass ceramics. Comparing with the glass,the luminescence quantum yield of the glass ceramics is also enlarged by about 3 times.This demonstrates the potential white light-emitting diode application of the glass ceramics produced in this letter.     

Broadband and High Efficient 1530 nm Emission from Oxyfluoride Glass Ceramics Codoped with Er3＋ and Yb3＋ Ions

The emission at 1530nm and its applications in optical communications are discussed. The efficient width of the emission band △eff, which is up to 91 nm, is larger as compared with silica-based glass, bismuth glass and ZrF4-BaF2-LaFa-AIF3-NaF （ZBLAN） glass doped by Er^3＋ ions. Under the excitation of 785 nm laser, the emission integral intensity of 153Onto increases about five times in the glass ceramics higher than that in the glass. This is explained by the quantum cutting process by two-photon emission with phonon assistance. The results indicate that the glass ceramics are a promising candidate for developing broadband optical amplifiers in wavelength-division multiplexed systems.     

Blue Upconversion Luminescence in Tm^3＋／Yb^3＋-Codoped Lead Chloride Tellurite Glass

The upconversion properties of Tm^3 /Yb3 -codoped lead chloride tellurite glass under 980hm excitation were investigated. The intense blue (476nm) emission and weak red (649 nm) emission corresponding to the ^1G4→4 ^3H6 and ^1G4→^3H4 transitions of Tm^3 ions, respectively, were simultaneously observed at room temperature. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms are evaluated. The intense blue upconversion luminescence of Tm^3 /Yb^3 -codoped lead chloride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.     

Transparent Ni^2＋-Doped MgO-Al2O3-SiO2 Glass Ceramics with Broadband Infrared Luminescence

We report on transparent Ni^2＋-doped MgO-Al2O3-SiO2 glass ceramics with broadband infrared luminescence. Ni^2＋-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 4.3 nm. No luminescence is detected in the as-prepared glass sample, while broadband infrared luminescence centred at around 1315 nm with full width at half maximum （FWHM） of about 300 nm is observed from the glass ceramics. The observed infrared emission could be attributed to the ^3T2g（^3F）→^3A2g（^3F） transition of octahedral Ni^2＋ ions in the MgAl2O4 crystallites of the transparent glass ceramics. The product of the fluorescence lifetime and the stimulated emission cross section is about 1.6×10^-24 s cm^2.     

Enhancement of up-conversion Yb3＋/Tm3＋/Er3＋ tri-doped tellurite glass luminescence properties in transparent oxyfluoride ceramics

Optically transparent Er3＋/Tm3＋/Yb3＋ tri-doped oxyfluoride tellurite based nano-crystallized glass ceramics with the batching composition of 73TeO2-15ZnO-7ZnF2-3YF3-1.5YbF3-0.3ErF3-0.2TmF3 （mol%） is prepared by a conventional melting quenching and the subsequent heat treatment processes. The sizes of grown nano-crystals in glass matrix appear to be smaller than 100 nm from the scanning electron mi- croscope measurement. Visible up-conversion luminescence of the as melted glass and glass ceramics is investigated. The three-color up-conversion luminescence intensities by 980-nm pumping are increased significantly due to the heat treatment, and the blue intensity increases with a higher magnitude than other wavelengths after heat treatment.     

Enhancement of up-conversion luminescence properties in Yb~(3+)/Tm~(3+)/Er~(3+) tri-doped transparent oxyfluoride tellurite glass ceramics

<正>Optically transparent Er~(3+)/Tm~(3+)/Yb~(3+) tri-doped oxyfluoride tellurite based nano-crystallized glass ceramics with the batching composition of 73TeO_2-15ZnO-7ZnF_2-3YF3-1.5YbF3-0.3ErF3-0.2TmF_3(mol%) is prepared by a conventional melting quenching and the subsequent heat treatment processes.The sizes of grown nano-crystals in glass matrix appear to be smaller than 100 nm from the scanning electron microscope measurement.Visible up-conversion luminescence of the as melted glass and glass ceramics is investigated.The three-color up-conversion luminescence intensities by 980-nm pumping are increased significantly due to the heat treatment,and the blue intensity increases with a higher magnitude than other wavelengths after heat treatment.     

Tm3+和Ho3+双掺氟锗酸盐玻璃的中红外发光性质质

用高温熔融法制备了Tm3+和Ho3+离子双掺的65GeO2-12AlF3-10BaF2-8Li2O-5La2O3氟锗酸盐玻璃,应用Judd-Ofelt理论,获得了Ho3+离子的强度参量（Ω2,Ω4,Ω6）,自发辐射跃迁几率Ar,辐射寿命τ等光谱参量。根据McCumber理论,计算了玻璃中Tm3+和Ho3+离子的吸收截面σa、受激发射截面σe和增益光谱G(λ)。在808nm激光二极管激发下,研究分析了Tm3+离子的交叉弛豫过程和Tm3+敏化Ho3+离子的2.0µm的红外发射光谱。结果表明,一定浓度Ho3+的共掺提高了Tm3+（3F4）→Ho3+（5I7）之间的能量转移效率,增强了~2.0µm的红外发光。     

掺铋BaF2晶体的制备及其近红外发光研究

通过温度梯度法制备了Bi₂O₃:BaF₂以及BiF₃:BaF₂晶体.在Bi₂O₃:BaF₂晶体中观察到了发光峰位于961 nm,半高宽202 nm的超宽带红外发光.在BiF₃:BaF₂晶体中检测到Bi²⁺和Bi³⁺可见区的发光,但是没有观察到红外发光.通过γ射线辐照实现了BiF₃:BaF₂晶体的近红外发光, 发光峰位于1135 nm,半高宽192 nm.讨论了Bi₂O₃和BiF₃掺杂BaF₂晶体的红外发光的机理. 关键词： 近红外发光 铋 氟化钡晶体 γ辐照     

Er3+/Yb3+共掺碲酸盐玻璃陶瓷的光谱性质

利用熔融淬火法在900℃下成功制备出原料比为60TeO2 -10CaF2 -25 H3 BO3-1 Er2 O3-4Yb2 O3的Er3+/Yb3+共掺杂透明玻璃陶瓷.利用XRD和TEM验证了玻璃陶瓷中存在Er2Te5O13纳米微晶,并由Raman测试得知其声子能量为886 cm-1.分别测量了其上转换和下转换发射谱,...     

Er~(3+)/Ce~(3+)共掺TeO_2-Bi_2O_3-TiO_2玻璃的热稳定性和光谱特性研究

用高温熔融法制备了Er3+/Ce3+共掺新型碲酸盐玻璃(TeO2-Bi2O3-TiO2).采用差热分析方法研究了玻璃的热稳定性,测试并分析了不同Ce3+离子掺杂浓度下Er3+离子的吸收光谱、上转换光谱和荧光光谱特性.研究结果表明,制备的碲酸盐玻璃具有很好的热稳定性,玻璃析晶温度Tx与玻璃转变温度Tg之差(ΔT=Tx-Tg)达到了185℃,高于其它文献的报道;同时,Ce3+离子共掺引入的能量转移(Ce3+∶2F5/2+Er3+∶4I11/2→Ce3+∶2F7/2+Er3+∶4I13/2)有效地抑制了Er3+离子上转换发光并显著增强了1.53μm波段荧光强度,而发射截面随着Ce3+离子掺杂浓度相应增大.优异的热稳定性以及光谱性能揭示Er3+/Ce3+共掺碲酸盐玻璃是一种潜在的制备宽带掺铒光纤放大器的理想增益介质.     

Determination of energy transfer and upconversion constants for Yb~(3+)/Er~(3+) codoped phosphate glass

<正>The energy transfer and cooperation upconversion processes are investigated in Yb~(3+)/Er~(3+) codoped phosphate glass.Based on the measured curves of output power versus incident power,the laser and spectroscopic parameters of the glass are fitted and analyzed.We focus on the resonant energy transfer constant k from Yb~(3+) to Er~(3+) as well as the cooperation upconversion coefficient C_(up) from ~4I_(13/2) of Er~(3+).The fitted k and C_(up) can give almost the same results for different thicknesses of glass disk with the same doping concentrations.The determination of these parameters is helpful for the development of Yb~(3+)/Er~(3+) codoped laser glass.     

Eu2+/Dy3+共掺SrSiO3透明微晶玻璃的光学性质

在还原气氛中采用高温熔融法制备了Eu2+-Dy3+共掺硅酸盐玻璃,热处理后得到了Eu2+-Dy3+共掺透明SrSiO3微晶玻璃。测试了样品的激发光谱和发射光谱,研究了不同Eu2+-Dy3+物质的量比下微晶玻璃发光的变化并计算了对应的色坐标。研究发现,样品发射光谱范围在400～600nm,其中400～550nm(绿光)的宽发射谱带来自Eu2+的5d→4f跃迁,而位于483nm(蓝光)和575nm(黄光)的尖峰则来自Dy3+的4F9/2→6 H15/2和4F9/2→6 H13/2跃迁;在紫外(UV)光(365nm)激发下通过调控Eu2+-Dy3+物质的量比可得到发白光的微晶玻璃,当Eu2+-Dy3+物质的量比为1∶8时,Eu2+-Dy3+共掺SrSiO3透明微晶玻璃所发白光最佳,对应的色坐标(0.268,0.356)位于CIE标准色坐标图的白光区域且最接近理想白光。结果表明,Eu2+-Dy3+共掺SrSiO3透明微晶玻璃可作为一种潜在的白光发光二极管用基质材料。     

Diode-pumped 65 fs Kerr-lens mode-locked Yb(3+):Lu(2)O(3) and nondoped Y(2)O(3) combined ceramic laser

Diode-pumped Kerr-lens mode-locked laser operation of Yb(3+):Lu(2)O(3) and nondoped Y(2)O(3) combined ceramics has been achieved; 65 fs pulses with an average power of 320 mW under 5 W of pump power were obtained at the center wavelength of 1032 nm. The spectral bandwidth and the time bandwidth product were 18.9 and 0.345 nm, respectively. To our knowledge, this is the first demonstration of a Kerr-lens mode-locked laser operation based on Yb(3+):Lu(2)O(3) ceramic.     

Enhanced luminescence from transparent Ni-doped MgO–Al2O3–SiO2 glass ceramics by Ga2O3 addition

Transparent Ni²⁺-doped MgO–Al₂O₃–SiO₂ glass ceramics without and with Ga₂O₃ were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga₂O₃ addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni²⁺-doped glass ceramics was largely enhanced by Ga₂O₃ addition which could mainly be caused by increasing of Ni²⁺ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga₂O₃ content was all more than 200 nm. The emission lifetime increased with the Ga₂O₃ content and the longest lifetime is about 250 μs. The Ni²⁺-doped transparent glass ceramics with Ga₂O₃ addition have potential application as broadband optical amplifier and laser materials.     

Ce3+,Tb3+共掺BaYF5微晶玻璃的光学特性

采用高温熔融法制备了一种新型的Ce3 +/Tb3+共掺BaYF5微晶玻璃.测试了微晶玻璃的X射线衍射图(XRD)谱、激发光普和发射光谱.研究发现:660℃热处理2h后的玻璃基质中析出BaYF5纳米晶相,根据XRD结果用Scherrer公式计算得到晶粒大小约为27 nm;在近紫外光(338 nm)激发下,观察到BaYF5...