Upconversion Luminescence Properties of Ho^(3+),Tm^(3+),Yb^(3+) Co-Doped Nanocrystal NaYF_4 Synthesized by Hydrothermal Method

Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3＋ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The result shows that Ho^3＋ ,Tm^3＋ , and Yb^3＋ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.

The effects of Er^(3+) ion concentration on 2.0-μm emission performance in Ho^(3+)/Tm^(3+) co-doped Na_(5)Y_(9)F_(32) single crystal under 800-nm excitation

Na_(5)Y_(9)F_(32) single crystals doped with ~0.8-mol% Ho^(3+),~1-mol% Tm^(3+),and various Er^(3+) ion concentrations were prepared by a modified Bridgman method.The effects of Er^(3+)ion concentration on 2.0-μm emission excited by an800-nm laser diode were investigated with the help of their spectroscopic properties.The intensity of 2.0-μm emission reached to maximum when the Er^(3+) ion concentration was ~1 mol%.The energy transfer mechanisms between Er^(3+),Ho^(3+),and Tm^(3+) ions were identified from the change of the absorption spectra,the emission spectra,and the measured decay curves.The maximum 2.0-μm emission cross section of the Er^(3+)/Ho^(3+)/Tm^(3+)tri-doped Na_(5)Y_(9)F_(32) single crystal reached 5.26 × 10^(-21) cm^(2).The gain cross section spectra were calculated according to the absorption and emission cross section spectra.The cross section for ~2.0-μm emission became a positive gain once the inversion level of population was reached 30%.The energy transfer efficiency was further increased by 11.81% through the incorporation of Er^(3+) ion into Ho^(3+)/Tm^(3+) system estimated from the measured lifetimes of Ho^(3+)/Tm^(3+)-and Er^(3+)/Ho^(3+)/Tm^(3+)-doped Na_(5)Y_(9)F_(32)single crystals.The present results illustrated that the Er^(3+)/Ho^(3+)/Tm^(3+)tri-doped Na_(5)Y_(9)F_(32) single crystals can be used as promising candidate for 2.0-μm laser.

Up-conversion photoluminescence characteristics of Yb^(3+):Er^(3+):Tm^(3+) co-doped borosilicate glasses

Yb^3＋：Er^3＋：Tm^3＋co-doped borosilicate glasses are prepared. Their strong up-conversion photoluminescence spectra in a range from ultra-violet to near-infrared, which are excited by a 978-nm laser diode, are measured, and the mechanisms of energy transfer among Yb^3＋ Er^3＋ and Tm^3＋ ions are discussed. The results show that there is an unexpected wavelength at 900-nm emission from Yb^3＋ Stark splitting levels to pump Tm^3＋ ions and there exists an optimum pump power. The concentration of the Tm^3＋ dopant gives rise to a prominent effect on the intensity of visible and near-infrared emissions for the yb^3＋：Er^3＋：Tm^3＋ co-doped borosilicate glasses.

1565nm激光泵浦Tm^3＋：Ho^3＋共掺石英光纤激光器动态特性

利用1565nm激光作为Tm3+:Ho3+共掺石英光纤激光器的泵浦带是一项较新的研究内容,动态特性能够有效反映激光振荡机制建立过程中能级粒子数和激光功率的变化情况,为系统实验的优化提供理论依据。建立了该泵浦带下系统的理论模型,基于速率方程和功率传输方程,采用离散算法,在Matlab软件中设置泵浦功率为3W、光纤长度2.5m条件下,分别对Tm3+:Ho3+共掺石英光纤的输入端、中点处和输出端的动态变化特性进行理论研究。结果表明:不同位置处,光纤对泵浦功率的吸收程度不同;光纤中粒子数和激光功率的弛豫振荡开始和持续的时间表现出较大差异,信号光振荡峰值远大于达到稳态时的功率;系统的光-光转化效率达到56%。

Tm^(3+)/Ho^(3+)共掺碲酸盐玻璃2.0μm发光性质研究

研究了Tm3+/Ho3+离子共掺碲酸盐玻璃的光谱性质,应用Judd-Ofelt理论计算了玻璃的各项光谱参数,推导了速率方程。表明3H4→3F4自发辐射跃迁几率很小,这一跃迁发射为一自终止系统。Tm3+离子3F4上粒子数主要来源于3H4+3H6→23F4的交叉弛豫过程。玻璃的荧光光谱表明,随着Ho2O3浓度的增加,Tm3+离子3F4→3H6跃迁的1.8μm发光强度降低,而Ho3+离子5I7→5I8跃迁的2.0μm发光强度迅速升高,说明Ho2O3浓度的增加,Tm3+离子和Ho3+离子间的能量转移作用逐渐加强。

Ho^3＋／Tm^3＋掺杂氟磷酸盐玻璃的研究

氟磷酸盐玻璃具有声子能量低、离子键性强、稀土离子掺杂浓度高、发光效率高等优点。采用正交设计法确定氟磷酸盐玻璃的配方为44KH2P04—40AlF3·3．5H2O-10BaF2—0．1Nb2O5，并采用该配方为基质制备了稀土Ho^3＋、Tm^3＋掺杂的氟磷酸盐玻璃，通过差热分析研究了该玻璃的形成过程；研究了Ho^3＋、Tm^3＋的掺杂量和Ho^3＋、Tm^3＋在该玻璃中的能级结构，测试了玻璃样品的吸收光谱，结果表明稀土掺杂的样品在416nm、448nm、537nm、641nm、684nm、791nm和1035nm处有明显的吸收峰，当稀土离子Ho^3＋、Tm^3＋的掺杂量为0．3mol％和1．5mol％时，稀土离子的特征吸收相对最强。

Tm^3＋与Ho^3＋单掺杂锗酸盐玻璃的增益特性

制备了掺杂浓度分别为2.0mol%的Tm3+及Ho3+单掺的两种锗酸盐玻璃。根据McCumber理论计算了Tm3+离子能级3H6←→3F4(1.8μm)跃迁和Ho3+离子能级5I8←→5I7(2.0μm)跃迁的吸收截面和受激发射截面。同时,根据所获得的吸收截面、发射截面以及掺杂离子的浓度分别获得了Tm3+离子和Ho3+离子在两种不同锗酸盐玻璃基质中的增益截面函数,从该函数可反映出材料的粒子数反转特性。对于Tm3+离子掺杂的锗酸盐玻璃,其吸收截面、发射截面和增益截面的最大值大于在氟锆酸盐、氟化物和氟氧化物玻璃中;对于Ho3+掺杂的锗酸盐玻璃,其吸收截面、发射截面和增益截面的最大值也大于在氟锆铝酸盐玻璃。因此,Tm3+和Ho3+掺杂的两种锗酸盐玻璃在~1.8和~2.0μm波段的中红外激光器中将有潜在的应用前景。

应用于2.1μm激光的Tm^(3+)/Ho^(3+)共掺氟碲酸盐微结构光纤研究

采用棒管法制备了低羟基含量的Tm^(3+)/Ho^(3+)共掺氟碲酸盐微结构光纤。当使用波长为1 560 nm的激光器泵浦Tm^(3+)/Ho^(3+)共掺光纤时,处于Tm^(3+)基态3H6的电子被激发至3F4能级,进一步通过Tm^(3+)和Ho^(3+)间的能量传递过程3F4→3H6(Tm^(3+)):5I8→5I7(Ho^(3+))(能量失配为745 cm-1)布居Ho^(3+)的5I7能级,5I7能级上的电子向5I8能级跃迁发射出2.1μm的光。使用1 560 nm光纤激光器作为泵浦源,18 cm长的Tm^(3+)/Ho^(3+)氟碲酸盐微结构光纤作为增益介质,获得了波长为2 063 nm的激光输出。所得激光的斜率效率为12.9%,激光阈值为163 m W,未饱和的最大输出功率为40 m W。研究结果表明,Tm^(3+)/Ho^(3+)共掺氟碲酸盐微结构光纤可用于制作2.1μm光纤激光器。

α-TeO2∶Tm^(3＋),Ho^(3＋),Yb^(3＋)纳米材料的红绿蓝色上转换发光(英文)

利用简单的水热合成法成功制备出α-TeO2∶Ho3+,Yb3+、α-TeO2∶Tm3+,Yb3+和α-TeO2∶Tm3+,Ho3+,Yb3+纳米材料,用980 nm的近红外光作为激发光源测定了样品的室温上转换发射光谱。结果表明:样品α-TeO2∶Ho3+,Yb3+分别发射绿光(545 nm)和红光(651 nm),分别对应于Ho3+离子的5S2→5I8和5F5→5I8能级跃迁。随着Yb3+的摩尔分数从5%增加到15%,样品在545 nm处的绿光强度明显变大,发光颜色由黄光向绿光转变。样品α-TeO2∶Tm3+,Yb3+在476 nm处发射出蓝光,对应于Tm3+离子的1G4→3H6能级跃迁,两个弱红光峰(651,675 nm)分别对应于Tm3+离子的1G4→3F4和3F2→3H6能级跃迁。随着Yb3+离子浓度的提高,蓝光与红光的相对强度也在显著提高。基于可调控性蓝光、绿光和红光的产生,α-TeO2∶Tm3+,Ho3+,Yb3+纳米材料能产生不同颜色的光,包括白光。

Tm^(3+)/Ho^(3+)离子掺杂中红外超快激光技术研究进展(特邀)

稀土离子Tm^(3+)/Ho^(3+)掺杂中红外2μm波段超快激光由于广泛的应用前景成为近十余年来激光领域的研究热点之一。文中首先综述了稀土离子Tm^(3+)/Ho^(3+)掺杂固体/光纤2μm波段超快激光锁模技术进展,包括主动锁模技术以及饱和吸收、克尔透镜、非线性偏振旋转、非线性光环形镜、非线性多模干涉等被动锁模技术;其次,结合激光增益介质及色散管理技术回顾了Tm^(3+)/Ho^(3+)掺杂固体和光纤锁模激光脉冲宽度压缩进展;再次,总结了Tm^(3+)/Ho^(3+)大能量/高功率超快激光技术及进展;最后,对2μm波段超快激光发展趋势进行了总结和展望。

Gain properties of germanate glasses singly doped with Tm^(3+) and Ho^(3+) ions

Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H6←→3F4 transitions of Tm3＋（at 1.8 μm） and the 5I8←→5I7 transitions of Ho3＋（at 2.0 μm） were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations.For Tm3＋-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses.For Ho3＋-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses.Hence, these Tm3＋-doped and Ho3＋-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.

LaF3:Yb^3+/Tm^3+、LaF3:Yb^3+/Ho^3+亚微米晶体的制备及表征

采用一步的离子热方法,以离子液体BmimBF4作为反应介质,成功制备了LaF3:Yb^3+/Tm^3+、LaF3:Yb^3+/Ho^3+自组装亚微米序列。产物发生了自组装现象,形成了类似于糖葫芦状的有趣形貌。研究发现,反应时间、反应温度、溶剂组成和混合溶剂中离子液体与水的比例等实验参数对最后产物的形貌有极大影响。这种材料具有理想的自组装形貌、良好的水分散性和明亮的上转换发光,因此使得它在生物标记和显示等领域具有潜在的应用。

Yb3+/Ho3+/Tm3+三掺杂LiTaO_(3)多晶材料的上转换发光特性

采用高温固相合成法制备了多组Yb^(3+)/Ho^(3+)/Tm^(3+)不同物质的量分数掺杂的LiTaO_(3)多晶材料,测试了双掺Yb^(3+)/Ho^(3+),Yb^(3+)/Tm^(3+)和三掺Yb^(3+)/Ho^(3+)/Tm^(3+)的LiTaO_(3)多晶的X射线衍射图谱、紫外-可见吸收谱和上转换荧光发射谱。X射线衍射(XRD)结果显示,稀土离子掺杂没有改变LiTaO_(3)多晶的物质结构,这表明稀土离子以取代基质离子的方式进入了晶格中。样品的紫外吸收边显示,增加Ho^(3+)或Tm^(3+)物质的量分数会导致吸收边先红移再蓝移。在980 nm泵浦光激发下,可见光区域中出现上转换蓝光(475 nm)、绿光(545 nm)和红光(663 nm和650 nm)发射,通过改变LiTaO_(3)中的激活离子Ho^(3+)-Tm^(3+)物质的量分数,可对上转换荧光色度进行调节,物质的量分数配比为2.0%Yb^(3+)/0.05%Ho^(3+)/0.4%Tm^(3+)的掺杂LiTaO_(3)多晶材料实现了最为接近标准白光的发射。

Sr_2CeO_4/Ln^(3+)(Ln=Er,Ho,Tm)的微波合成与荧光性质

首次采用微波法合成了Sr2CeO4/Ln3+(Ln=Er,Ho,Tm)荧光体.研究了样品的荧光性质,并观察到Er3+,Ho3+,Tm3+掺杂的Sr2CeO4材料的上转换发光现象.荧光光谱证实,存在基质Sr2CeO4向稀土离子Ln3+的能量传递.

Tm3+/Ho3+/Yb3+掺杂Ga2O3-GeO2-Li2O玻璃的上转换发光性能研究

采用熔融淬冷法制备了Tm^3＋/Ho^3＋/Yb^3＋掺杂的Ga2O3-GeO2-Li2O玻璃。测试了样品的拉曼光谱、吸收光谱、980 nm和808 nm泵浦下的上转换发射光谱。详细调查了在980 nm和808 nm激发下不同的Yb2O3掺杂含量对Tm^3＋/Ho^3＋掺杂的镓锗锂玻璃的上转换发射光谱的影响,分析了稀土离子间的能量传递。研究发现：980 nm泵浦下样品观察到明显的545 nm和657 nm发射和微弱的476 nm发射峰。随着Yb^3＋浓度的增大,由于Yb^3＋对Tm^3＋和Ho^3＋的有效的能量传递增强了红光和绿光发射强度,红光的增长率是快于绿光的,Yb2O3的掺杂量为0.7 mol%时I657/I545强度比率达到最高。808 nm激发下可以观察到弱的476 nm的蓝光和545 nm的绿光及强烈693 nm发射。

Energy transfer and 2 μm emission in Tm^(3+)/Ho^(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders

（Y0.87La0.1Zr0.03）2O3 nanopowders doped with various concentrations of Tm^3＋ and Ho^3＋ were prepared by the citrate method. The standard cubic Y2O3 phase can be matched in the Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2 O3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm^3＋ to Ho^3＋ and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to 3 F4→3 H6 transition of Tm^3＋ and 5 I7→5 I8 transition of Ho^3＋, respectively.Better spectral properties were achieved in Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2O3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm^3＋ and 1 mol% Ho^3＋.

稀土离子掺杂CaY_(1-x)AlO_(4):xRE^(3+)(RE=Dy,Ho,Sm,Tm)荧光材料的发光性能

采用溶胶凝胶法合成稀土离子掺杂Ca Y_(1-x)Al O_4∶xRE^(3+)(RE=Dy,Ho,Sm,Tm)荧光粉。采用X射线粉末衍射仪(XRD)、高分辨率透射电镜(TEM)和荧光分光光度计(PL)分别对荧光粉的物相结构、形貌以及荧光性能进行表征。研究结果表明,所合成样品为四方晶系结构的纳米级材料,在紫外光激发下,掺杂离子均表现出特征的f-f电子跃迁发射,当Dy^(3+)、Ho^(3+)、Sm^(3+)和Tm^(3+)的掺杂摩尔分数分别为0.03,0.015,0.015,0.02时,样品发光强度最大,分别发射出白光、绿光、橙光和蓝光。

Enhanced 1.8 μm emission in Er^(3+)/Tm^(3+) co-doped lead silicate glasses under different excitations for near infrared laser

A detailed study of the fluorescence emission properties and energy transfer mechanism in Er^（3＋）/Tm^（3＋） co-doped lead silicate glasses was reported. Enhanced near infrared 1.8 μm and visible up-conversion emissions were investigated under 808 and 980 nm excitations, respectively. The energy transfer mechanism between Er^（3＋） and Tm^（3＋） was analyzed according to the absorption spectra, the emission spectra and the level structures of Er^（3＋） and Tm^（3＋）. The energy transfer efficiency between Er^（3＋） and Tm^（3＋） reached 68.1% in the Er^（3＋）/Tm^（3＋） co-doped lead silicate glasses when pumped by 808 nm laser diode. Based on the absorption spectra, the Judd-Ofelt parameters, spontaneous emission probability, absorption and emission cross sections, gain coefficients were calculated and analyzed. It was found that the calculated emission cross section and the maximum gain coefficient around 1.8 μm were 4.9×10^（–21）cm^2 and 1.12 cm^（–1）, respectively. These results indicated that the Er^（3＋）/Tm^（3＋） co-doped lead-silicate glasses had potential application in near infrared lasers.

Bi_2O_3对Tm^(3+)/Ho^(3+)/Yb^(3+)共掺碲酸盐玻璃三基色上转换发光的影响

用高温熔融法制备了Tm3+/Ho3+/Yb3+共掺碲酸盐玻璃样品,在TeO2-ZnO-La2O3玻璃组分的基础上,引入声子能量较低的重金属氧化物Bi2O3,研究了Bi2O3组分对基质样品拉曼光谱和Tm3+/Ho3+/Yb3+共掺样品上转换发光光谱的影响。结果发现,在975 nm波长激光二极管(LD)激励下,制备的碲酸盐玻璃样品中可以观察到强烈的红光(662 nm)、绿光(546 nm)和蓝光(480 nm)三基色上转换发光。随着重金属氧化物Bi2O3组分含量的增加,玻璃基质的最大声子能量降低,Tm3+/Ho3+/Yb3+共掺样品的三基色上转换发光强度均有所提高,且Bi2O3组分的引入对上转换蓝光发光强度的影响要大于其对绿光和红光的影响。

Tm^(3+)/Ho^(3+)共掺镓铋酸盐玻璃1.47μm发光特性和能量传递的研究

报道了Tm3+/Ho3+共掺的镓铋酸盐玻璃14Ga2O3-25Bi2O3-20GeO2-31PbO-10PbF2玻璃1.47μm(S波段)发光和能量传递特征,应用Judd-Ofelt理论计算了玻璃的强度参数Ωt(t=2,4,6),自发辐射概率A、荧光分支比β,荧光辐射寿命τ等各项光谱参数以及有效荧光线宽Δλeff和峰值发射截面σepeak.通过测量荧光光谱和荧光寿命研究了Ho3+离子掺杂浓度对Tm3+离子1.47μm波段发光性能的影响,分析了Tm3+和Ho3+之间的能量传递过程.结果表明一定浓度内Ho3+的共掺迅速降低了Tm3+:3F4能级的粒子数,而对3H4能级粒子数影响不大,从而降低了3F4和3H4能级间布居数反转的难度,极大地提高了1.47μm发光效率.研究表明镓铋酸盐玻璃是适用于S波段光纤放大器的一种潜在基质材料,而掺杂一定浓度的Ho3+离子有利于提高Tm3+离子在1.47μm波段的发光效率.