Formation of Infrared Femtosecond Laser Induced Colour Centres in Tb^3＋－Doped and Tb^3＋／Ce^3＋－Codoped Heavy Germanate Glasses and Tb3＋／Ce3＋－Codoped Heavy Germanate Glasses ＊

The formation of infrared femtosecond laser induced colour centres was observed in Tb^3 -doped and Tb^3 /Ce^3 -codoped heavy germanate glasses. A rectangular scan was made by focusing the laser beam inside the glasssamples. A three-dimensional yellowish block was created from the path and it corresponded to the appearanceof broad absorption bands in the absorption spectra. The irradiation induced absorption coefficient μ(λ) wasused to characterize the distribution of radiation induced colour centres in the samples, whose peak was locatedat 380 nm and extended to the longer wavelength. Ce^3 ions were found not only to inhibit the formation ofcolour centres, but also to enhance the recovery.     

Laser Characteristics of Cladding-Pumped Short Er^3＋/yb^3＋ Codoped Single Mode Phosphate Glass Fibre

We experimentally investigate the laser characteristics of a series of short pieces of newly-developed Er^3＋/ Yb^3＋ codoped single mode phosphate glass fibres via the cladding pump of a 976nm multimode laser diode. A stable continuous-wave single transverse mode laser with over 85 m W at 1553nm is generated from a 5.5-em-long active fibre. Single mode laser output power per unit length is up to 15 mW/cm. Moreover, the slope efficiency is 11.8% when the pump power is below 940mW and the 3dB linewidth is 0.06nm at the maximum pump power. The numerical simulation results show that the laser emission slope efficiency can exceed 20% by means of increasing the coupling efficiency of the pump to the fibre core further.     

Efficient Fibre Amplifiers Based on a Highly Er3＋/Yb3＋ Codoped Phosphate Glass-Fibre

Highly Er3＋ /yb3＋-codoped single-mode phosphate glass fibre is fabricated by the rod-in-tube technique. The performances of high-concentration Er3＋ /yb3＋-codoped phosphate glass fibre amplifiers are investigated and discussed. An efficient optical fibre amplifier with a gain of 12.6 dB based on a 3.0 cm long Era＋ /ybe＋-codoped phosphate glass fibre is demonstrated under a dual-pump configuration with two 976 nm fibre-pigtail laser diodes, which make it attractive for compact Er3＋-doped fibre amplifiers. The obtedned noise figures of signal wavelength from 1525 to 1565nm are less than 6.0dB. Gain saturation behaviour at 1535nm is also investigated, and the obtained saturation output power is larger than 10 dBm.     

Spectroscopic properties in Er3＋/yb3＋ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.     

Determination of energy constants for Yb3＋/Er3＋ transfer and upconversion codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate 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 Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.     

Abnormal Visible Luminescence Mechanism of Tb^3＋-Yb^3＋ Codoped SiOu-Al2O3-CaF2 Glass Studied by Time-Resolved Spectra

The upconversion energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass is investigated by time-resolved spectra. The effect of donor ion Yb^3＋ is involved in the dynamic decay behavior of acceptor ion Tb^3＋, which provides direct proof for the energy transfer from Yb^3＋ to Tb^3＋. The pump power dependence curves show that the upconversion luminescence is a two-photon process. The measured decay curves of the 5D4 state （Tb^3＋） contain two parts： a slow decay process corresponding to its radiation, and a fast one with a decay parameter approximately twice the lifetime of the ^2F5/2 state （Yb^3＋ ）. The fast decay process is contradictory to the generally accepted cooperative sensitization upconversion rate equation model. Since the effect of the host environmental is excluded by comparative experiments, we believe that there should be another energy transfer mechanism in Tb^3＋-Yb^3＋ co-doped SiO2-Al2O3-CaF2 glass in addition to the cooperative sensitization process.     

稀土离子(Eu3+,Tb3+,Ce3+)掺杂ZnAl2O4/SiO2微晶玻璃的制备与发光性能

采用凝胶法分别制备出4.5ZnO-5.5Al2 O3-90SiO2 (ZAS)以及ZAS∶ RE3+(RE=Eu,Tb,Ce)透明微晶玻璃.利用X射线衍射仪(XRD)、透射电子显微镜(TEM)和荧光光谱仪(PL)等测试手段,研究了稀土离子掺杂浓度对ZAS微晶玻璃的结构和发光性能的影响.XRD结果表明,ZAS∶ RE3+(RE=Eu,Tb,Ce)微晶玻璃包含ZnAl2 O4晶相和SiO2非晶相,ZnAl2 O4平均晶粒尺寸约为30 nm,稀土离子的掺杂没有显著改变原来的ZnAl2O4晶体结构.TEM结果表明,900℃时ZnAl2O4从ZAS体系中析出.PL光谱显示,Eu3+存在5 D0→7F2跃迁,ZAS∶Eu3+在611 nm处发出强烈的红色光;由于Tb3+的5D4→7E跃迁,ZAS∶ Tb3+在541 nm处发出明亮的绿色光;ZAS∶ Ce3+在381 nm处显示了蓝光发射,对应于Ce3的5d→4f轨道跃迁.ZAS∶RE3+(RE =Eu,Tb,Ce)的PL发射光谱存在着浓度猝灭现象,Eu3+、Tb3+和Ce3+的最佳单掺杂摩尔分数分别为20％、20％和3％.CIE色度图表明,ZAS∶ RE3+(RE=Eu,Tb,Ce)的色坐标分别位于红光、绿光和蓝光区域.实验结果表明,ZAS∶RE3+(RE=Eu,Tb,Ce)微晶玻璃是一种良好的可用于全色显示的白光LED材料.     

Emission enhancement in Er^3＋/Pr^3＋-codoped germanate glasses and their use as a 2.7-μm laser material

Emission enhancement at 2.7 μm is observed in Er^3＋/Pr^3＋--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient energy transfer between Er^3＋ and Pr^3＋; the energy transfer efficiency is as high as 77.4%. The mechanisms of energy transfer are discussed in detail. The calculated emission cross-section of Er^3＋/Pr^3＋- codoped germanate glass is 8.44× 10 ^-21 cm^2, which suggests that Er^3＋/Pr^3＋-codoped germanate glass can be used to achieve efficient 2.7-μm emission.     

Spectroscopic properties and energy transfer processes in Er3＋/Nd3＋ co-doped tellurite glass for 2.7-μm laser materials

Intense 2.7-μm emissions are obtained from Er³⁺/Nd³⁺ co-doped tellurite glass samples under the 808-nm laser diode excitation.According to the absorption spectra,Judd-Ofelt parameters and radiative transition probabilities are calculated and analyzed using the Judd-Ofelt theory.The spectroscopic properties and energy transfer mechanism between Er³⁺ and Nd³⁺ are analyzed.The effects of OH^- content on the spectroscopic properties of Er³⁺/Nd³⁺ co-doped samples are discussed.The obtained results indicate that Er³⁺/Nd³⁺ co-doped tellurite glass can significantly develop optical properties of 2.7-μm emission,if OH^- exoups can be effectivelv eliminated.     

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...     

钇镓石榴石中Tb3+到Ce3+的无辐射能量传递特征

在Y₃Ga₅O₁₂石榴石中,室温下采用紫外激光选择激发光谱研究了能量从Tb³⁺的⁵D₃和⁵D₄能级无辐射传递给Ce³⁺的²D_3/2能级。实验结果符合Frster-IH直接无辐射传递理论。⁵D₃(Tb³⁺)→²D_3/2(Ce³⁺)能量传递是电偶-偶极子相互作用机理,其平均临界传递距离为R₀=16.3?,而⁵D₄(Tb³⁺)→²D_3/2能量传递是起主导作用的电偶-偶极子相互作用,其平均临界传递距离为11.2?。在⁵D₄的传递过程中,电偶-四极子相互作用也应予以考虑。 关键词：     

Decay of the Ce3+ luminescence of LaMgAl11O19 : Ce3+ and of CeMgAl11O19 activated with Tb3+ or Eu3+

Decay measurements have been performed on the Ce³⁺ luminescence of LaMgAl₁₁O₁₉ : Ce³⁺ and of CeMgAl₁₁O₁₉ activated with Tb³⁺. For all samples, the decay was found to be nearly exponential over at least two decades, and the decay time constant was practically the same, being ≈20 ns. From these results and from quantum efficiency data of the Ce³⁺ luminescence, conclusions are drawn about the various energy transfers and quenching interactions occurring in these compounds.     

Diffusion-limited energy transfer from Tb3+ → Nd3+ and Tb3+ → Ho3+ in DMSO

The energy transfer phenomenon has been studied from Tb³⁺ → Nd³⁺ and Tb³⁺ → Ho³⁺ in DMSO. A diffusion limited dipole-dipole mechanism of energy transfer is suggested for both systems. At high acceptor concentrations, P_da depends linearly on C² consistent with the Fong and Diestler theory of energy transfer. However, at low acceptor concentrations the observations of time evolutions of Tb³⁺ luminescence decay following flash excitation has enabled us to examine diffusion limited energy transfer from Tb³⁺ to Nd³⁺ and Tb³⁺ to Ho³⁺ in DMSO.     

Ce3+/Tb3+/Sm3+共掺CaO-B2O3-SiO2玻璃的光学性能调控

采用高温熔融法制备了Ce³⁺/Tb³⁺/Sm³⁺掺杂的CaO-B₂O₃-SiO₂（CBS）发光玻璃。通过傅利叶红外光谱仪、荧光光谱仪表征了该系列发光玻璃的微观结构和发光性质,并对Ce³⁺到Tb³⁺、Ce³⁺到Sm³⁺之间的能量传递机制进行了研究。结果表明,在339,378,407 nm激发下,单掺Ce³⁺、Tb³⁺和Sm³⁺的CBS玻璃分别发射紫蓝光、绿光和红光,恰好符合混合合成白光的条件。Ce³⁺/Tb³⁺和Ce³⁺/Sm³⁺双掺CBS玻璃的发射光谱以及Ce³⁺衰减寿命的变化证实了Ce³⁺→Tb³⁺和Ce³⁺→Sm³⁺之间存在能量传递,随Tb³⁺和Sm³⁺浓度增加,Ce³⁺的寿命减小,且传递效率由5.4%和5.7%分别增加至24.0%和27.1%。调节3种稀土离子的掺杂浓度并选择合适的激发波长,实现了发光颜色可调,并最终获得白光发射。     

Dy3+对Tb3+激活硅酸盐氟氧闪烁玻璃发光性能的影响

采用高温熔融法制备了Dy3+或Tb3+单掺和Dy3+/Tb3+共掺硅酸盐氟氧闪烁玻璃。通过对傅里叶变换红外光谱、透射光谱、光致激发和发射光谱、X射线激发发射光谱及荧光衰减曲线的分析,研究Dy3+与Tb3+之间的能量传递关系以及Dy3+对Tb3+激活硅酸盐氟氧闪烁玻璃发光性能的影响。实验结果表明：Dy3+/Tb3+共掺硅酸盐氟氧闪烁玻璃具有较高的密度和良好的可见区透过率,玻璃的网络结构是由[SiO₄]四面体和[AlO₄]四面体连接构成。在紫外光激发时,Dy3+单掺玻璃的发光源于Dy3+的4F_9/2→6H_15/2(483 nm),6H_13/2(576 nm)的跃迁发射,而Tb3+单掺玻璃的发光则源于Tb3+的5D₄→7F₆(489 nm),7F₅(544 nm),7F₄(586 nm)和7F₆(623 nm)的跃迁发射。对于Dy3+/Tb3+共掺玻璃,发射光谱则主要由Tb3+的荧光发射组成。通过对不同波长紫外光激发的发射光谱分析发现,Dy3+/Tb3+共掺闪烁玻璃中存在多种形式的能量传递。在以Dy3+的特征激发452 nm为激发波长时,Tb3+单掺玻璃的发光很弱。但随着Dy3+的引入,通过4F_9/2(Dy3+)→5D₄(Tb3+)的能量传递,Tb3+发光得到敏化增强。Dy3+/Tb3+共掺玻璃的发光强度随着Dy₂O₃含量的增多而增强,Dy₂O₃含量为1 mol%时达到最大,更高Dy₂O₃含量的样品由于Dy3+的浓度猝灭,减少了向Tb3+的能量传递,发光强度减弱。当激发波长减小到350 nm时,Dy3+和Tb3+均被激发到更高的能级6P_7/2(Dy3+)和5L₉(Tb3+),此时除了4F_9/2(Dy3+)→5D₄(Tb3+)的能量传递外,还出现了5D₄(Tb3+)→4F_9/2(Dy3+)的能量回传。Dy3+掺杂浓度较低时,Dy3+→Tb3+能量传递作用较强,Tb3+发光得到敏化增强。随着Dy₂O₃含量的增多,Tb3+→Dy3+能量传递作用增强。当Dy₂O₃含量超过0.4 mol%时,Tb3+→Dy3+能量传递强于Dy3+→Tb3+能量传递,减少了Tb3+的辐射跃迁发光,因此Dy3+/Tb3+共掺玻璃的发光强度开始减弱。由于Gd3+向Dy3+或Tb3+均可进行有效的能量传递,因此在以Gd3+的特征激发274 nm为激发光时,Dy3+/Tb3+共掺玻璃中出现了Dy3+和Tb3+对Gd3+传递能量的竞争。随着Dy₂O₃含量的增多,Tb3+所获得的能量不断减少,同时伴随着Tb3+→Dy3+能量回传和Dy3+之间的无辐射交叉弛豫作用,Dy3+/Tb3+共掺玻璃的发光强度不断减弱。对Dy3+/Tb3+共掺闪烁玻璃中Tb3+的5D₄→7F₅荧光衰减曲线分析还发现,随着Dy₂O₃含量的增多,Tb3+的荧光寿命从2.24 ms缩短到1.15 ms,曲线从单指数形式变为双指数形式,进一步证明玻璃中存在5D₄(Tb3+)→4F_9/2(Dy3+)的能量回传。X射线激发发射光谱显示,Dy3+的引入对Tb3+激活闪烁玻璃的辐射发光具有很强的负面影响,而这种负面影响不足以通过Dy3+→Tb3+能量传递来弥补,因此Dy3+/Tb3+共掺玻璃的辐射发光强度随着Dy₂O₃含量的增多而不断减弱。由此可见,在Tb3+激活硅酸盐氟氧闪烁玻璃中,不宜将Dy3+作为敏化剂,用于增强Tb3+的发光。     

Eu~(2+)-Yb~(3+)共掺磷酸盐玻璃中的合作能量传递(英文)

报道了在Eu2+-Yb3+共掺磷酸盐中,一个紫外光子(320nm)通过下转换发光变成两个近红外光子(约1 000nm)的现象.测试了不同样品的吸收、激发和发射光谱,证明了在本玻璃体系中量子剪裁现象的存在;Eu2+离子5d-4f能级发光的衰减曲线证明Eu2+到Yb3+之间的合作能量传递;用I-H理论模型拟合衰减曲线说明了能量传递的过程.最后计算出了能量传递的效率,当Yb3+浓度为1.0mol%时效率为23.05%,当其增加到2.0mol%时,能量传递效率提高到了53.6%.     

基质对Tb3+单掺荧光玻璃发光性质的影响

采用高温熔融法制备了Tb³⁺单掺硼酸盐、硅酸盐和磷酸盐荧光玻璃和相应的玻璃基质。根据紫外-可见透射光谱计算了Tb³⁺在不同基质中从⁷F₆ 到⁵D₃和 ⁵D₄能级的实验振子强度,解释了不同基质中Tb³⁺发射光谱的变化原因。结果表明：因为对称性差,在磷酸盐玻璃基质中,Tb³⁺在542 nm和585 nm处的发射峰有劈裂现象。在硼酸盐和硅酸盐基质中,Tb³⁺ 的⁵D₃能级上的粒子通过交叉弛豫过程被倒空并转移到⁵D₄能级,故⁵D₃能级发光（413 nm和436 nm）不明显;在磷酸盐基质中,Tb³⁺的⁵D₃能级上的粒子数较少,没有交叉弛豫产生,故⁵D₃能级发光最强。在3种基质中,Tb³⁺从⁵D₄能级发射的特征峰489,542,585,620 nm的强度顺序是硼酸盐>硅酸盐>磷酸盐,与Tb³⁺在不同基质中从⁷F₆ 到 ⁵D₄能级的实验振子强度顺序一致。