Spectroscopic properties and diode-pumped 1594 nm laser performance of Er:Yb:Li6Y(BO3)3 crystal

An Er³⁺/Yb³⁺-codoped Li₆Y(BO₃)₃ crystal was grown by the Czochralski method. The polarized absorption spectra and the fluorescence decay curve were recorded. The efficiency of energy transfer from Yb³⁺ to Er³⁺ ions was estimated. Quasi-continuous-wave output power of 325 mW at 1594 nm was realized under the absorbed pump power of 10.4 W in a hemispherical cavity. The absorbed pump threshold and slope efficiency of the laser are 6.0 W and 7.2%, respectively. PACS 42.55.Xi; 42.70.Hj     

掺铒矾酸钇晶体上转换荧光研究

使用波长为808和658nm的半导体激光器和染料激光器作为激发源，测量了Er³⁺：YVO₄晶体的波长在553和410nm附近的上转换荧光.对激发过程的分析表明，贡献于上转换荧光的主要激发机制为激发态吸收.在不同浓度下对上转换荧光的寿命测量结果显示，随Er³⁺浓度的提高，553nm绿光的荧光寿命随浓度的增加而减小，但410nm的荧光寿命随Er³⁺浓度无明显变化.结合绿光强度随掺杂浓度增加而减小的结果，认为在所测浓度范围内 关键词：     

Spectroscopic characteristics of Pr<Superscript>3+</Superscript> in biaxial La<Subscript>2</Subscript>(WO<Subscript>4</Subscript>)<Subscript>3</Subscript> crystal

A Pr³⁺-doped La₂(WO₄)₃ crystal grown by the Czochralski method has been investigated as a promising laser material. The principal axes of the optical indicatrix and Pr³⁺ concentration of the crystal were determined. The polarized absorption, fluorescence spectra and fluorescence decay curves of the main emission multiplets of the crystal were measured at room temperature. The spectroscopic parameters were obtained by the modified Judd–Ofelt theory combined with the normalized method. The peak stimulated emission cross-sections of the major emission lines were estimated. The good spectroscopic properties imply that the Pr³⁺:La₂(WO₄)₃ crystal is a potential laser gain medium for solid-state laser and self-stimulated Raman laser applications. PACS 78.20.-e; 42.70.Hj     

Fluorescence Spectra of Eu3+ and Tb3+ Doped Na6 Ln (BO3)3 (Ln = La,Gd, Y) Phosphors

The fluorescence properties of Eu^{3 +} and Tb³⁺ doped Na₆La(BO₃)₃, Na₆Gd(BO₃)₃, Na₆Y(BO₃)₃, Na₆(Gd, Y) (BO₃)₃ powder phosphors are reported. These phosphors display fluorescent RED and GREEN colours when droped with Eu³⁺ and Tb³⁺ ions, respectively. The best fluorescence performance was consistantly observed from the Na-Gd based hosts. The photoluminescence spectra were analysed by evaluating colour coordinates, relative intensity ratios, and stimulated emission cross-sections.     

Growth and spectroscopic properties of Yb-doped Li6Y(BO3)3 single crystal

The spectroscopic properties of high-quality Czochralski grown 20% Yb³⁺-doped Li₆Y(BO₃)₃ single crystal as new promising laser material are presented. The crystal was seeded-grown in the 〈0 1 0〉 direction and its crystallinity was measured using X-ray rocking curve analysis. Low temperature transmission spectrum exhibits broad bands in a short range of wavelengths and two sharp lines at 972.5 and 978 nm, interpreted as two zero-lines of two nonequivalent Yb³⁺ centers inside the lattice. The fluorescence lifetimes associated to these two intense lines are different: 0.867 and 1.33 ms. An attempt of determination of the Stark sublevels energies of the ⁴F_5/2 and ⁴F_7/2 manifolds of the two Yb³⁺ nonequivalent ions is given. The polarized absorption and emission spectra were also recorded at room temperature and we conclude that the most favorable emission line for laser application could be around 1042 nm in n_g polarization.     

Emission analysis of Li6LuY(BO3)3:Tb3+,Dy3+ phosphors

In this paper, we present the synthesis and luminescence properties of Tb³⁺ and Dy³⁺-doped lithium lutetium yttrium borate (Li₆LuY(BO₃)₃) phosphors. We have adopted the well-known solid state reaction method for the synthesis of these phosphors. The emission intensities of the synthesized phosphors were found to reach their maximum, when doped by 1 mol% of Tb³⁺ and 3 mol% of Dy³⁺, beyond which emission intensities decrease due to concentration quenching. The homogeneous phase, crystalline structure and uniform morphology of the synthesized phosphors were confirmed by X-ray diffraction analysis (XRD) and Scanning electron microscopy (SEM). The X-ray and UV–VIS-induced luminescence, decay time and CIE chromaticity were investigated for the synthesized phosphors.The X-ray induced integrated light yield was measured to be 82% for Li₆LuY(BO₃)₃:Tb³⁺ (LLYBO) and 59% for Li₆LuY(BO₃)₃:Dy³⁺ of that of commercially available X-ray imaging material; Gd₂O₂S:Tb³⁺ (Gadox).LLYBO:Tb³⁺ phosphor displayed five major emission bands that correspond to ⁵D_j → ⁷F_j transitions. The 1931 Commission Internationale de l'Eclairage (CIE) chromaticity coordinates were also measured.     

Growth and spectroscopic characterization of Er: Sr3Y(BO3)3 crystal

This paper reports the growth and spectroscopic characterization of Er³⁺:Sr₃Y(BO₃)₃ crystal. Er³⁺:Sr₃Y(BO₃)₃ crystal with dimensions up to ∅20×35 mm³ has been grown by Czochralski method. The polarized spectroscopic properties of Er³⁺:Sr₃Y(BO₃)₃ crystal were investigated. Based on the Judd-Ofelt theory, the effective intensity parameters Ω_t were obtained: Ω₂=1.71×10⁻²⁰ cm², Ω₄=1.39×10⁻²⁰ cm², Ω₆=0.74×10⁻²⁰ cm² for π-polarization, and Ω₂=1.77×10⁻²⁰ cm², Ω₄=1.44×10⁻²⁰ cm², Ω₆=0.65×10⁻²⁰ cm² for σ-polarization. The emission cross-section σ_em was calculated to be 4.75×10⁻²¹ cm² for π-polarization at 1536 nm and 6.30×10⁻²¹ cm² for σ-polarization at 1537 nm. The investigated results showed that Er³⁺:Sr₃Y(BO₃)₃ crystal may be regarded as a potential laser host material for 1.55 μm IR solid-state lasers.     

Growth, spectroscopic characteristics and laser potential of Yb3+:Ca3La2(BO3)4 crystal

Crystal of Yb³⁺-doped Ca₃La₂(BO₃)₄ has been grown by the Czochralski technique. The room temperature absorption and fluorescence spectra of the crystal have been investigated. The result showed that this crystal exhibits broad absorption and emission with the FWHM of 11 nm at 978 nm and 66 nm FWHM at 1025 nm, respectively. The stimulated emission cross-section of Yb³⁺ ions were calculated using the reciprocity method and Fuchtbauer-Ladenburg method, respectively. The room temperature fluorescence decay curves of ² F _5/2 manifold of Yb³⁺ ions were recorded for both crystal and powder samples. The effect of radiation tapping on the spectroscopic properties is discussed. The result that the lifetime of the powder sample is shorter than that of the bulk sample demonstrates the existence of radiation trapping effect. The laser potentiality was also evaluated and the results show that this crystal is a good candidate for tunable and ultrashort pulse lasers.     

Enhanced 1.53-μm and lowered upconversion luminescence in Er-doped Ga2O3-GeO2-Bi2O3-Na2O glass by codoping rare earths

Spectroscopic properties and energy transfer (ET) in Ga₂O₃-GeO₂-Bi₂O₃-Na₂O (GGBN, glass doped with Er³⁺ and rare earths (RE³⁺; RE³⁺=Ce³⁺, Tb³⁺) have been investigated. Intense 1.53-μm emission with the peak emission cross-section achieved to 7.58×10⁻²¹ cm² from Er³⁺-doped GGBN glass has been obtained upon excitation at 980 nm. Effects of RE³⁺ (RE³⁺=Ce³⁺, Tb³⁺) codoping on the optical properties of Er³⁺-doped GGBN glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 μm emission intensity and decrease of upconversion (UC) fluorescence with increasing Ce³⁺ concentration have been observed. The incorporation of Tb³⁺ into Er³⁺-doped GGBN glass could significantly decrease the UC emission intensity, but meanwhile decrease the 1.53 μm emission intensity due to the ET from Er³⁺:⁴I_13/2 to Tb³⁺:⁷F₂. The results indicate that the incorporation of Ce³⁺ into Er³⁺-doped GGBN glass can effectively improve 1.53-μm and lower UC luminescence, which makes GGBN glass more attractive for use in C-band optical fiber amplifiers.     

Luminescent properties of (Y,Gd)BO3:Bi,RE (RE=Eu, Tb) phosphor under VUV/UV excitation

Bi³⁺- and RE³⁺-co-doped (Y,Gd)BO₃ phosphors were prepared and their luminescent properties under vacuum ultraviolet (VUV)/UV excitation were investigated. Strong red emission for (Y,Gd)BO₃:Bi³⁺,Eu³⁺ and strong green emission for (Y,Gd)BO₃:Bi³⁺,Tb³⁺ are observed under VUV excitation from 147 to 200 nm with a much broader excitation region than that of single Eu³⁺-doped or Tb³⁺-doped (Y,Gd)BO₃ phosphor. Strong emissions are also observed under UV excitation around 265 nm where as nearly no luminescence is observed for single Eu³⁺-doped or Tb³⁺-doped (Y,Gd)BO₃. The luminescence enhancement of Bi³⁺- and RE³⁺-co-doped (Y,Gd)BO₃ phosphors is due to energy transfer from Bi³⁺ ion to Eu³⁺ or Tb³⁺ ion not only in the VUV region but also in the UV region. Besides, host sensitization competition between Bi³⁺ and Eu³⁺ or Tb³⁺ is also observed. The investigated phosphors may be preferable for devices with a VUV light 147-200 nm as an excitation source such as PDP or mercury-free fluorescent lamp.     

Thermally stimulated recombination processes and luminescence in Li<Subscript>6</Subscript>(Y,Gd,Eu)(BO<Subscript>3</Subscript>)<Subscript>3</Subscript> crystals

The thermally stimulated recombination processes and luminescence in crystals of the lithium borate family Li₆(Y,Gd,Eu)(BO₃)₃ have been investigated. The steady-state luminescence spectra under X-ray excitation (X-ray luminescence spectra), the temperature dependences of the X-ray luminescence intensity, and the glow curves for the Li₆Gd(BO₃)₃, Li₆Eu(BO₃)₃, Li₆Y_0.5Gd_0.5(BO₃)₃: Eu, and Li₆Gd(BO₃)₃: Eu compounds have been measured in the temperature range 90–500 K. In the X-ray luminescence spectra, the band at 312 nm corresponding to the ⁶ P _J → ⁸ S _7/2 transitions in the Gd³⁺ ion and the group of lines at 580–700 nm due to the ⁵ D ₀ → ⁷ F _J transitions (J = 0–4) in the Eu³⁺ ion are dominant. For undoped crystals, the X-ray luminescence intensity of these bands increases by a factor of 15 with a change in the temperature from 100 to 400 K. The possible mechanisms providing the observed temperature dependence of the intensity and their relation to the specific features of energy transfer of electronic excitations in these crystals have been discussed. It has been revealed that the glow curves for all the crystals under investigation exhibit the main complex peak with the maximum at a temperature of 110–160 K and a number of weaker peaks with the composition and structure dependent on the crystal type. The nature of shallow trapping centers responsible for the thermally stimulated luminescence in the range below room temperature and their relation to defects in the lithium cation sublattice have been analyzed.     

荧光俘获效应对掺饵氧化物玻璃光谱性质的影响

测试了不同掺杂浓度和样品厚度下掺铒磷酸盐和碲酸盐玻璃的吸收光谱、荧光光谱和荧光寿 命，计算了Er³⁺离子在1.53 μm处的吸收截面(σ_a)、发射截面(σ _e)、自发辐射跃迁概率(A_rad)、辐射跃迁寿命(τ_rad) 、以及辐射跃迁量子效率(η)等光谱参数.讨论了荧光俘获效应对掺铒磷酸盐和碲酸盐玻璃 光谱性质及光谱参数的影响.结果表明即使在铒离子低掺杂浓度(0.1 mol% Er₂O ₃)下，荧光俘获效应也普遍存在于掺铒玻璃材料中，使得荧光寿命(τ_{f)和荧光半高宽(FWHM)随样品的厚度和铒离子掺杂浓度增加而增大，导致碲酸盐和磷酸 盐玻璃中τf分别增加11%—37％和6%—17%，FWHM分别增加15%—64%和11%—55% ，使得掺铒玻璃材料的放大品性参数(σe×FWHM) 也相应被估高.由于铒离子在 碲酸盐玻璃中在1.53 μm处吸收和发射截面重叠面积较大，加之铒离子在前者基质中的发射 截面高于后者，使得掺铒碲酸盐玻璃中的荧光俘获效应高于磷酸盐玻璃. 关键词： 荧光俘获 铒离子 碲酸盐玻璃 磷酸盐玻璃}     

掺铒高硅氧玻璃光谱性质的研究

应用Judd-Oflet理论计算了新型掺铒高硅氧玻璃中铒离子的强度参量Ω_t(t=2,4,6)，Ω₂=8.15×10^-20，Ω₄=1.43×10^-20，Ω₆=1.22×10^-20，相比于其他氧化物玻璃，表现出较大的Ω_2,6值，反映了铒离子周围的近邻结构不对称性和Er-O键的离子键成分较高.利用McCumber理论计算得到了能级^{关键词： 掺铒高硅氧玻璃 Judd-Ofelt理论 量子效率}     

混合形成体对掺铒碲酸盐玻璃的热力学稳定性和发光性能的影响

研究了混合形成体效应对掺铒碲酸盐玻璃热力学稳定性、1.53 μm发光特性和上转换发光强度的影响.通过拉曼光谱测试,分析了WO₃,Nb₂O₅,GeO₂等氧化物对Er³⁺离子配位场结构,以及对发光谱的非均匀展宽机理的作用.结果表明,通过掺杂适当声子能量的网络形成体氧化物,不但可获得热力学稳定性较好的玻璃,还可有效降低Er³⁺离子⁴I_11/2能级的寿命,在抑制Er³⁺离子在可见光波段的上转换发光的同时不致劣化其在1.53 μm的发光特性.本文制得的碲酸盐玻璃具有较大的受激发射截面((9.64—10.96)×10^-21cm²)和荧光半高宽(FWHM)(50—67 nm),热力学稳定性良好,是一种理想的掺Er³⁺宽带有源光纤用基质玻璃. 关键词： 掺铒碲酸盐玻璃 混合形成体 1.53 μm发光 声子能量     

GENERATION OF MULTI-WAVELENGTH VISIBLE LIGHT IN Er3+-DOPED AND Er3+/Yb3+-DOPED SINGLE-MODE OPTICAL FIBER PUMPED AT 1313 nm

We report the generation of multi-wavelength visible light through amplified spontaneous emission (ASE) in Er³⁺-doped and Er³⁺/Yb³⁺-doped germanosilicate single-mode optical fiber pumped by a Nd:YLF laser at 1313nm. In the Er³⁺-doped fiber, the intense multi-wavelength blue emission hnes around 463-510nm corre-spond to transitions born ²G_7/2 etc. excited states to the metastable ⁴I_13/2 state, and their pumping mechanists is aecomphshed by a stepwise four-photon absorption. Some emission hnes in this wavelength region are attributed to the three-wave sum-frequency process of 1313 and 1530nm (corresponds to ⁴I_13/2 -⁴I_15/2). The intense green emission hnes at 525 and 540 nm are also observed in the Er³⁺-doped fiber. In the Er³⁺/Yb³⁺-doped fiber the blue and green lines are very weak compared with those in the Er³⁺-doped fiber.     

Er3+，Tm3+共掺的NaY(WO4)2晶体的光谱分析和上转换发光

在室温下，测量了Er:Tm:NaY(WO₄)₂晶体的吸收光谱、激发光谱、发射光谱以及上转换发光，并运用J-O理论对测量的结果进行了计算，得出了Er:Tm:NaY(WO₄)₂晶体的强度参数.报道了Tm，Er离子间特殊的能量传递和相关上转换，解释了离子间的能级跃迁过程.同时，对于Er增强Tm离子近红外发光的特性也作了充分研究. 关键词： 4)₂晶体')" href="#">Er:Tm:NaY(WO₄)₂晶体 吸收光谱 发射光谱 激发光谱 上转换     

Polarized spectral analysis of Er3+ ions in biaxial Bi2(MoO4)3 crystal

An Er³⁺:Bi₂(MoO₄)₃ single crystal has been grown by the Czochralski technique. The Stark sublevels of the ⁴I_15/2 and ⁴I_13/2 multiplets of Er³⁺ ions in the crystal were determined. The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curve of the crystal were measured at room temperature and the relevant spectroscopic parameters, including the Judd–Ofelt intensity parameters, spontaneous emission probability, fluorescence branching ratio, radiative lifetime, and stimulated emission cross section, were estimated. The effect of re-absorption on the spectroscopic parameters was discussed. When the crystal was excited at 977 nm, up-conversion green fluorescence was observed and discussed.     

单晶电子顺磁共振研究中零场分裂张量主轴的确定

用电子顺磁共振二维旋转测角器确定量子化轴即零场分裂张量的一个主轴,根据矢量的正交关系计算与量子化轴垂直的主轴平面上的取向二维角组、以便按照计算的二维角组测量电子顺磁共振谱,确认零场分裂张量的另外两个主轴,同时确定了主轴座标系(X,Y,Z)相对实验座标系(x,y,z)的Euler角。以渗Cr³⁺的Na₃(AlMo₆O₂₄H₆)·8H₂O单晶的电子顺磁共振测量作为上述方法的一个应用例子。 关键词：     

WO3对掺铒碲酸盐玻璃光谱性质的影响

制备了掺铒碲钨酸盐玻璃(80-x)TeO₂-(10+x)WO₃-8BaO-2Na₂O-0.5Er₂O₃(x=0,5,10,15,20)玻璃,研究了WO₃对掺铒碲钨酸盐玻璃的光谱性质. 研究发现：随着WO₃含量的增加,Ω₄,Ω₆先增加后减小,受 关键词： 碲钨酸盐玻璃 3+光谱性质')" href="#">Er³⁺光谱性质 Judd-Offelt理论     

Upconversion emission enhancement in Er/Yb-codoped BaTiO3 nanocrystals by tridoping with Li ions

Er³⁺/Yb³⁺/Li⁺-tridoped BaTiO₃ nanocrystals were prepared by a sol-gel method to improve the upconversion (UC) luminescence of rare-earth doped BaTiO₃ nanoparticles. Effects of Li⁺ ion on the UC emission properties of the Er³⁺/Yb³⁺/Li⁺-tridoped BaTiO₃ nanocrystals were investigated. The results indicated that tridoping with Li⁺ ion enhanced the visible green and red UC emissions of Er³⁺/Yb³⁺-codoped BaTiO₃ nanocrystals under the excitation of a 976 nm laser diode. X-ray diffraction and decay time of the UC luminescence were studied to explain the reasons of the enhancement of UC emission intensity. X-ray diffraction results gave evidence that tridoping with Li⁺ ion decreased the local symmetry of crystal field around Er³⁺, which increased the intra-4f transitions of Er³⁺ ion. Moreover, lifetimes in the intermediate ⁴ S_3/2 and ⁴I_11/2 (Er) states were enhanced by Li⁺ ion incorporation in the lattice. Therefore, it can be concluded that Li⁺ ion in rare-earth doped nanocrystals is effective in enhancing the UC emission intensity.