Upconversion properties of Er^3＋/Yb^3＋ co-doped TeO2-Nb2O5-Li2O glasses

The Er^3＋/Yb^3＋ co-doped TeO2-Nb2O5-Li2O glass is prepared by conventional melting method, and its upconversion spectra are measured. The intense green upconversion luminescence upon excitation with a 976 nm laser diode is observed with the naked eyes. The dependence of luminescence intensity on the ratio of Yb^3＋/Er^3＋ is discussed in detail, and the relationship between the ratio of green luminescence intensity to red luminescence intensity and the ratio of Yb^3＋/Er^3＋ is also studied, The luminescence intensity increases with the ratio of Yb^3＋/Er^3＋ increasing. The ratio of Yb^3＋/Er^3＋ plays a more important role than the concentration of Er^3＋ in determining the upconversion luminescence intensity. The ratio of green luminescence intensity to red luminescence intensity reaches a maximum when ratio of Yb^3＋/Er^3＋ is 3. Thus the glass could be one of the potential candidates for LD pumping solid-state lasers.     

Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） Glasses for 1.47-μm Optical Amplifications

We report the spectroscopic properties and thermal stability of Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） glasses for 1.47-μm optical amplifications. Effects of PbF2 doping on the optical properties and thermal stability of Tm^3＋ -doped gallate-germanium-bismuth-lead glass are inestigated. The measured peak wavelength and full width at half-maximum of the fluorescence are 1465nm and - 120 nm, respectively： Siguificant enhancement of the 1.47-μm emission and the lifetime of a a^3H4 level with increasing PbF2 doping have been observed. The presence of GeO2 provides two potentials of increasing the thermal stability and shortening the ultraviolet cutoff band of host glasses.     

Effect of B2O3 on Judd—Ofelt parameters of Er^3＋—doped tellurite glasses

We have prepared Er^3 -doped borotellurite glasses using conventional melting and quenching method.The absorption spectrum analysis is performed on the basis of Judd-Ofelt theory.The effects of B2O3 on the spectroscopic parameters such as intersity parameters,line strengths of electric-dipole transitions,and sopontaneous emission probability are discussed.     

High Efficiency Infrared to Visible Upconversion in Er3＋／yb3＋—Doped Lead Halide Tellurite Glass

Strong upconversion luminescence of Er3 /Yb3 -doped lead halide tellurite glass under 976nm excitation is demonstrated. Three emission bands centred at 525 nm, 545 nm, and 655 nm resulting from the transitionsfrom the excited states 2H11/2, 4S3/2, and 4F9/2 to the ground state 4I15/2, respectively, are observed evenat 60mW pumping power. The power dependent intensity and the upconversion mechanisms responsible forthe luminescence are evaluated and discussed. The obtained results might provide useful information for thedevelopments of upconversion lasers.     

Preparation and spectral characterization of new Er3+-doped TeO2－B2O3－WO3－ZnO－ZnS glasses

Erbium-doped TeO_2-based oxysulfide glasses have been prepared in argon atmosphere in graphite crucibles. The results of thermal analysis and spectroscopic properties of Er^{3+} have been studied in terms of sulfide influence. As a function of composition, we have measured principally the optical absorption, spontaneous emission, and lifetime of the materials. Judd－Ofelt theory was introduced to calculate bandwidth and emission cross-section of Er^{3+}. The results demonstrate that addition of sulfide in tellurite glasses results in broad emission spectra, with high emission cross-section, slightly low emission lifetime and a comparatively high thermal stability as pure oxide glasses.     

Er3+,Yb3+共掺磷酸盐玻璃沟道波导放大器

在自行研制的Er3 ，Yb3 共掺磷酸盐玻璃基质上用离子交换方法制作出沟导光波导放大器。在110mW的抽运功率下(抽运光波长为980nm)，在1．8cm长的器件上获得了3．8dB的小信号(信号光波长为1．55μm)增益，单位长度上的增益为2．1dB／cm。     

Er3+和Yb3+共掺碲酸盐玻璃的光谱性质

研究了Er3+ 和Yb3+ 共掺碲酸盐玻璃的吸收和荧光光谱性质 ,分析了碲酸盐玻璃中Er3 + 的上转换发光机制 ,应用Judd Ofelt理论计算了玻璃的强度参量Ωt(t =2 ,4,6 ) ,分别为Ω2 =4.74× 10 - 2 0 cm2 ,Ω4=1.46× 10 - 2 0 cm2 ,Ω6 =0 .6 4× 10 - 2 0 cm2 ,计算了Er3+ 离子的自发跃迁几率、荧光分支比 ,应用McCumber理论计算了受激发射截面 ,并比较了Er3 + 在不同基质玻璃中的光谱特性。     

Ar^2＋离子和H2,O2分子碰撞过程中激发态的研究

在Ar~(2 )离子和H_2,O_2分子碰撞实验研究中,发现这两个碰撞体系都存在三个激发通道:(1)双电子俘获激发通道,(2)单电子俘获激发通道,(3)靶直接激发通道。实验结果得到了ArⅠ,ArⅡ和HⅠ,OⅠ的发射截面,并分别比较了Ar~(2 ) H_2,Ar~(2 ) O_2,He~(2 ) H_2,He~(2 ) O_2碰撞体系的发射截面。     

Cd3Al2SiO12玻璃中Er^3＋的光学跃迁

根据Judd-Ofelt理论,利用镉铝硅酸盐玻璃中Er^3 的吸收光谱,计算了实验与理论振子强度,用量小二乘法拟合实验与理论振子强度得到了三个J－O强度参数Ω2,Ω4,Ω6。并由此计算了Er^3 在不同能级之间的自发辐射系数A、辐射寿命τ、荧光分支比β以及积分发射截面∑。根据这些参数分析认为掺铒镉铝硅酸盐玻璃可能实现近红外激光输出。     

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.     

纳米晶Gd2O3：Eu^3＋的制备及发光性能

采用低温燃烧合成法制备了Gd2O3：Eu^3＋纳米晶。用X射线衍射仪（XRD）、高分辨透射电子显微镜（HRTEM）和荧光光谱仪分别对样品的结构、形貌和发光性能进行了研究。结果表明，改变甘氨酸与稀土离子的比例（G／M）、退火温度可以制备出不同结构和晶粒尺寸的Gd2O3：Eu^3＋纳米晶。在退火温度为800℃，G／M等于0．83和1．0时，均得到了纯立方相的Gd2O3：Eu^3＋纳米晶，随着G／M的增加，Gd2O3：Eu^3＋从立方相逐渐向单斜相转变。粉末的晶粒尺寸随着退火温度的增高而增大，晶粒尺寸在10-30nm之间。立方相的Gd2O3：Eu^3＋纳米晶主发射峰位置在612nm（^5D^0→^7F2跃迁），激发光谱中电荷迁移态发生了红移。     

含Eu3+离子的Na2O-K2 O-SiO2-Al2O3系统玻璃的制备及其变温发射光谱与结构特性

通过高温熔融法制备了含Eu^3 离子的Na2O-K2O-SiO2-Al2O3系统玻璃。在488nm波长光的激发下，系统地研究了上述玻璃从77K到700K温度范围的变温发光特征。发现总的荧光强度首先随温度的升高而大幅度升高，然后随温度的升高而减少，用声子辅助吸收与热激活过程及温度淬灭效应定性地解释了上述强度的变化，同时测量与分析了Eu^3 离子的晶格场参量。结果表明，Eu^3 离子与氧离子的距离随着温度升高而变短，而Eu^3 离子的配位数不随温度而变化。     

不同介质里Gd2O3：Eu^3＋纳米晶中Eu^3＋的自发辐射

对不同介质包围的Gd2O3：Eu^3＋纳米颗粒的发光性质进行了研究。从发射光谱观察到Eu^3＋的4f组态内跃迁峰位受周围介质的影响不大。Gd2O3纳米颗粒中Eu^3＋的^5D0的自发发射寿命受周围介质的局域场影响很大,主要与介质的有效折射率和纳米颗粒的填充率有关。有两种模型可以描述自发辐射寿命与周围介质的相互作用：Onsanger-实腔模型与Lorentz虚腔模型。本实验结果表明,实腔模型比较合理,而虚腔模型与实验数据偏差较大。     

纳米晶Gd2O3：Eu^3＋的制备与发光性质

利用共沉淀法制备了纳米晶Gd2O3:Eu3+发光粉体. 在不同掺杂浓度、不同煅烧温度的系列样品中,均观测到Eu3+离子的特征发射.样品的晶相与发射性质的研究表明:所制备的样品经800~1 300 ℃热处理后,晶相为立方相,1 400 ℃时开始向单斜相转变.荧光强度与Eu3+离子掺杂浓度关系研究表明:在不同掺杂浓度中,Eu3+离子浓度为4%时其相对发射强度最强.在三个不同的煅烧温度中,经800 ℃煅烧的样品其发光效果最好.此外还观察到电荷转移激发态以及基质、Gd3+与Eu3+之间的能量传递.激发谱包含三部分,即电荷转移带、Eu3+的4f内壳层电子跃迁和Gd3+的激发谱.     

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.     

Sr3B2O6：Tb^3＋，Li^＋绿色荧光粉的发光特性

用高温固相法合成了Sr3B2O6：Tb^3＋,Li^＋绿色荧光粉,并研究粉体的发光性质。发射光谱由位于黄绿区的4个主要荧光发射峰组成,峰值分别位于495,548,598,625nm,对应了Tb^3＋的^5D4→^7F6,^5D4→^7F5,^5D4→^7和^5D4→^7F3特征跃迁发射,548nm的发射最强。激发光谱表现从200—400nm的宽带,可以被近紫外光辐射二极管（near-ultraviolet light-emitting diodes,UVLED）管芯产生的350-410nm辐射有效激发。研究了Tb^3＋掺杂和电荷补偿剂对样品发光亮度的影响。Sr3B2O6：Tb^3＋,Li^＋是一种适用于白光LED的绿色荧光粉。     

Luminescence and Energy Transfer of Eu^2＋, Mn^2＋ in SrZnP2O7

The SrZnP2OT：Eu^2＋, Mn^2＋ phosphor is synthesized by high temperature solid state reaction. The luminescence properties and the energy transfer between Eu^2＋ and Mn^2＋ are investigated. The emission bands of this phosphor peaked at 42Ohm and 67Ohm are originated from the 5d → 4f transition of Eu^2＋ and from the 4T1 （4G） --〉 6A1 （6S） transit/on of Mn^2＋, respectively. With the increasing Mn^2＋ concentration, the intensity of fixed concentra- tion Eu^2＋ decreases and the intensity of Mn^2＋ also increases. It is suggested that there is an energy transfer from Eu^2＋ to Mn^2＋ in SrZnP2O7 host. According to Dexter＇s energy transfer formula of multipolar interaction, the energy transfer between Eu^2＋ and Mn^2＋ is due to the electric dipole-quadrupole interaction of the resonance transfer.     

Visible Upconversion Emission in Er3＋—Doped GeO2—PbO—PbF2 Glass

The upconversion fluorescence emission of Er3 -doped 60GeO2-2OPbO-2OPbF2 glass was experimentally investigated under the pump of 976-nm laser diode. The results reveal the existence of intense emission bands centred around 524, 545, and 657nm at room temperature. The green emission at 524 and 545nm is due to the 4S3/2 2 Hll/2→ 4I15/2 transition and the red emission of 657nm originates from the 4F9/2-→4I15/2 transition of Er3 . The quadratic dependence of the green and red emissions on excitation power indicates that a two-photonabsorption process occurs under the 976-nm excitation. The excited- state absorption from 4I ll/2 and the cross relaxation between two Er3 ions in the 4I ll/2 state contribute to the green emission. The red emission at 657nm is attributed to the excited-state absorption and cross relaxation processes in the 4I13/2 level as well as the 4S3/2 level nonradiative transition of Er3 .