Spectroscopic properties and mechanism of Tm^(3+)/Er^(3+)/Yb^(3+) co-doped oxyfluorogermanate glass ceramics containing BaF_2 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.

氟氧化物玻璃材料中Er^(3+)的光谱性质

利用J O理论计算了Er3 + 掺杂的氟氧化物玻璃材料MFT的光学性质 ,得到了一些能级间跃迁的振子强度、跃迁几率、分支比、及寿命等数据。并通过实验测量了吸收光谱、激发光谱和发射光谱等。

Er^(3+)和Yb^(3+)共掺氟氧化物微晶玻璃的研究

制备了Er3+、Yb3+共掺的SiO2-Al2O3-PbF2-CdF2系统玻璃,并进行相应的微晶化热处理,研究了氟氧化物微晶玻璃中Er3+离子的上转换发光特性.研究结果表明:原始玻璃经热处理后得到的β-PbF2相氟氧化物微晶玻璃,Er3+和Yb3+所在局域基质声子能量的降低,使微晶玻璃中Er3+上转换发光强度显著提高,而微晶化后Er3+、Yb3+离子局域环境发生变化,导致微晶玻璃中Er3+离子的绿光上转换荧光强度较强,而红光上转换荧光强度相对较弱.

Yb^(3+)-Er^(3+)共掺硼磷酸盐玻璃光谱性质的成分依赖性

以Yb3+-Er3+共掺的B2O3 -P2O5 -MO-R2O-Al2O3 (M=Zn,Ca,Sr,Ba;R=Li,Na,K)玻璃系统为研究对象,分别分析了B2O3 的含量以及加入不同种类的碱金属和碱土金属氧化物对玻璃的光谱性质的影响.研究结果表明,随着B2O3 含量的提高,玻璃的自发辐射跃迁几率降低,辐射寿命增长,但吸收截面、相应的积分吸收截面和发射截面减小,玻璃的折射率在B2O3 含量为15% (摩尔分数)时达到极小值.随着修饰体阳离子场强的升高,吸收截面和发射截面有增大趋势.

Investigation of Silver Nanostructures and Their Influence on the Fluorescence Spectrum of Erbium-Doped Glasses

Sodium borate glasses embedded with silver were made by the melt quenching technique. Glass transition temperature was recorded by thermal analysis of the sample. As made glasses revealed emission in the visible region under nitrogen laser and excimer laser excitations. Heat treatment was used to induce silver metallic particles. Absorption spectra revealed a peak at 417 nm due to surface Plasmon resonance. Particle size was estimated to be 2.6 ± 0.2 nm. Erbium and silver co-doped multielement oxide glasses were made by the melt quenching technique followed by heat treatment to induce nanoparticles. In heat treated samples, Er3+ luminescence increased 4× due to enhanced field in the vicinity of silver particles. Under excimer laser excitation, Er3+ and 2% Ag co-doped glass revealed Er3+ transitions due to enhanced field at the rare-earth ions. Under 795 nm laser excitation Er3+ green upconversion signals are found to be 4× stronger in 2% Ag co-doped, heat treated sample, than the others.

Structural and optical studies of Yb^(3+),Er^(3+) and Er^(3+)/Yb^(3+) co-doped phosphate glasses

Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy. The absorption, emission spectra and fluorescence decay studies were carried out both at low and room temperatures. Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass. Up-conversion and cooperative fluorescence were also discussed.

Preparation and characterization of Er^(3+)-Yb^(3+)-Ce^(3+) co-doped transparent glass ceramic containing nano Ca_5(PO4)_3F crystals

A transparent glass ceramic tri-doped with Ce3＋/Er3＋/yb3＋ was fabricated by the high-temperature melting technique and following heat-treatment. X-ray diffraction and transmission electron microscope results demonstrated that Cas（PO4）3F（FAP） nanocrystals, possessed with preferable emission performances for the 1.54 μm transition for doping Er3＋, were homogeneously pre- cipitated among the glass matrix with a mean size of 30 rim. Addition of Ce3＋ greatly enhanced 1.54 ~tm fluorescence of Er3＋ by the cross relaxation energy transfer between Er3＋ and Ce3＋. Meanwhile, incorporation of Ce3＋ dramatically decreased the visible upcon- version emission intensity of glass ceramic than that of glass, suggesting that Ce3＋ might incorporate into the FAP nanocrystals. The properties of this transparent glass ceramic showed the potential application as an efficient 980 nm pumped infrared laser medium.

Silver nanoparticles enhanced near-infrared luminescence of Er^3＋/Yb^3＋ co-doped multicomponent phosphate glasses

A new way to improve the 1.53μm emission in Er3＋/Yb3＋ co-doped multicomponent phosphate glass was demonstrated by introducing silver nanoparticles （NPs） in rare-earth doped glass. The existence of Ag NPs was confirmed by absorption spectra and transmission electron microscopy （TEM） measurements. The homogeneous distribution of silver NPs could be observed by the TEM images. UV-Vis-NIR absorption spectra revealed that the surface plasmon band was centered at about 420 nm. The photoluminescence spectra of glass samples were used to investigate the effect of silver NPs on the fluorescence properties of Er3＋. Efficient 1.53μm emis-sion was obtained in prepared samples when pumped at 980 nm laser diode （LD）. The 1.53μm emission intensity could be enhanced 87% by doping 2 mol.% AgCl due to the increased localized field effect in the vicinity of NPs and the possible energy transfer from silver NPs to Er3＋ions. Our present work may point out one way to enhance the gain coefficient of Er3＋/Yb3＋ co-doped glass fiber.

Effect of concentration quenching on the spectroscopic properties of Er^(3+)/Yb^(3+) co-doped AlF_3-based glasses

A series of highly Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses have been investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and upconversion spectra have been performed to examine the effect of Er^(3+)/Yb^(3+) concentration quenching on spectroscopic properties. In the glasses with Er^(3+) concentrations below 10 mol%, concentration quenching is very low and the Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses have stronger fluorescence of 1.54μm due to the ~4I_(13/2)→~4I_(15/2) transition than that of Er^(3+) singly-doped glasses. As Er^(3+) concentrations above 10 mol% in the Er^(3+)/Yb^(3+) co-doped samples, concentration quenching of 1.54μm does obviously occur as a result of the back energy transfer from Er^(3+) to Yb^(3+). To obtain the highest emission efficiency at 1.54μm, the optimum doping-concentration ratio of Er^(3+)/Yb^(3+) was found to be approximately 1:1 in mol fraction when the Er^(3+) concentration is less than 10 mol%.

An investigation on the magneto-optic properties of terbium gallium garnet under high magnetic field

This paper reports that a series of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J-O intensity parameters Ωk （k = 2, 4, 6）, spontaneous radiative lifetime Trad, spontaneous transition probability A, fluorescence branching ratio β and oscillator strength fed of the Nd3＋ ions at room temperature are calculated based on Judd-Ofelt （J-O） theory. The temperature dependence of the up-conversion photoluminescence characteristics in a Nd3＋：Er3＋：Yb3＋ co-doped sample is studied under a 978 nm semiconductor laser excitation, and the energy transfer mechanisms among Yb3＋, Er3＋ and Nd3＋ ions are analysed. The results show that the J-O intensity parameters Ω2 increase when the Nd3＋ concentration of the Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses increases. The possibility of spontaneous transition is small and lifetimes are long at levels of 4F5/2 and 4F3/2. The intensity of Nd3＋ emissions at 595, 691, 753, 813 and 887 nm axe markedly enhanced when the sample temperature exceeds 400 K. The reasons being the cooperation of the secondary sensitization from Era＋ to Nd3＋ and the contribution of a multi-phonon.