Blue upconversion luminescence in Tm3+/Yb3+ co-doped new oxyfluoride tellurite glass

The thermal stability, Raman spectrum and upconversion properties of Tm3+/Yb3+ co-doped new oxyfluoride tellurite glass are investigated. The results show that Tm3+/Yb3+ co-doped oxyfluoride tellurite glass possesses good thermal stability, lower phonon energy, and intense upconversion blue luminescence. Under 980-nm laser diode (LD) excitation, the intense blue (475 nm) emission and weak red (649 nm) emission corresponding to the 1G4 → 3H6 and 1G4 → 3F4 transitions of Tm3+ ions respectively,were simultaneously observed at room temperature. The possible upconversion mechanisms are evaluated.The intense blue upconversion luminescence of Tm3+/Yb3+ co-doped oxyfluoride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.     

Strong upconversion luminescence in Er~(3+)/Yb~(3+)-doped halide modified tellurite glass

Upconversion luminescence of Er3+/Yb3+-doped halide tellurite glass is investigated experimentally upon 976-nm excitation. Three intense emissions centered at 525, 545 and 655 nm owing to the transitions 2H11/2→4I15/2,4S3/2→4I15/2 and 4F9/2→4I15/2, respectively, are observed when pumping power is as low as 20 mW. The upconversion mechanisms and power dependent intensities are discussed. The high-populated 4I11/2 level is supposed to serve as the intermediate state responsible for the upconversion processes.     

Research on upconversion luminescence in new Er3+/Yb3+codoped oxyfluoride borosilicate glass ceramics

The upconversion luminescence of Er3+/Yb3+ ions is researched in a novel transparent oxyfluoride borosil icate glass and glass ceramics under 980-nm excitation.Fluoride nanocrystals Ba2 YF7 are successfully precipitated in glass matrix,which is affirmed by the X-ray diffraction results.Compared with the parent glasses.significant enhancement of upconversion luminescence is observed in the Er3+/Yb3+ codoped transparent glass-ceramics.which may be due to the variation of coordination environment around Er3+ and Yb3+ ions after crvstallization.The possible upconversion mechanism is also discussed.     

基于铒镱共掺光纤光栅光学上转换的实验研究

通过载氢和紫外光曝光在铒镱共掺光纤上制作了光纤光栅,当波长为976.4nm的半导体连续激光泵浦该光栅时,在只有4mW的抽运功率水平下,便可以观察到显著的上转换蓝绿光辐射,随泵浦功率的增加,辐射强度也在增加。通过单色仪和光电倍增管记录到了绿光、蓝光、紫光和紫外等多波长的上转换辐射光。利用显微镜数码相片证实在同种铒镱共掺光纤中没有上转换现象。     

Highly efficient upconversion emission and luminescence switching from Yb3+/Tm3+ co-doped water-free low silica calcium aluminosilicate glass

We present highly efficient 480 and 800 nm upconversion emissions in Tm³⁺/Yb³⁺ co-doped water-free low silica calcium aluminosilicate glass under excitation at 976 nm. As a result of this efficient upconversion process, a luminescent switching with the excitation intensity has been observed. The switching is explained and discussed using rate equations analysis and saturation effects. By means of fitting of the experimental data point, it was possible to obtain the value of the energy transfer parameter related to the transition ²F_5/2, ³H₄→²F_7/2, ¹G₄. The value of this parameter is higher than that of materials like YLF. This switching mechanism could be used in the development of sensors and networks for optical processing and optical communications.     

Tm3+/Yb3+共掺氧卤碲酸盐玻璃上转换发光研究

研究了Tm3+/Yb3+共掺氧卤碲酸盐玻璃的上转换发光光谱,分析了TmO3量对Tm3+/Yb3+共掺氧卤碲酸盐玻璃上转换发光的影响机理.结果表明:在Tm3+/Yb3+共掺氧卤碲酸盐玻璃的上转换发光中,Tm3+存在较强的浓度猝灭效应.随Tm2O3含量增加,Tm3+的上转换蓝光和红光强度先增加,后降低,在0.1 mol% Tm2O3达到最大.该结果有助于进一步提高Tm3+的上转换发光效率.     

Yb3+/Ho3+/Tm3+共掺碲酸盐玻璃的上转换白光发射及其机理研究

采用高温熔融法分别制备了Yb3+/Ho3+,Yb3+/Tm3+和Yb3+/Ho3+/Tm3+共掺的碲酸盐玻璃。在980nm红外激光激发下,Yb3+/Ho3+/Tm3+共掺的玻璃样品显示了强的蓝光、绿光和红光发射,分别对应于Tm3+的1 G4→3 H6跃迁、Ho3+的5 F4(5 S2)→5I 8跃迁以及Ho3+的5 F5→5I 8和Tm3+的1 G4→3 F4跃迁。通过对比发现,Yb3+/Ho3+/Tm3+共掺样品中的红、绿光积分发射强度比值(3.95)明显大于Yb3+/Ho3+共掺样品(1.69),这是由于Ho3+和Tm3+间存在交叉弛豫过程3 H4(Tm3+)+5I 6(Ho3+)→3 F4(Tm3+)+5 F5(Ho3+)和3 F4(Tm3+)+5I 8(Ho3+)→3 H6(Tm3+)+5I 7(Ho3+)所致。在激发功率密度为8.2 W.cm-2时,Yb3+/Ho3+/Tm3+共掺样品的上转换发光色坐标值为x=0.345,y=0.338,非常接近于等能白光(x=0.333,y=0.333)。     

Tm3+/Yb3+共掺铋碲酸盐玻璃中的高效蓝色上转换荧光

制备了高折射率Tm3+/Yb3+共掺杂铋碲酸盐玻璃,利用棱镜耦合法测量出玻璃在632.8和1550 nm波长处的折射率分别为2.0365和1.9795. 对玻璃的吸收、荧光和红外透过光谱展开了测试与分析,根据Judd-Ofelt理论对吸收光谱进行拟合,求得Tm3+的振子强度参数Ωt(t=2,4,6)分别为3.90×10-20, 2.03×10-20和9.03×10-21 cm2,并进一步计算了Tm3+在玻璃中各能级跃迁的振子强度、自发辐射跃迁概率、辐射寿命和荧光分支比等光谱参数. 在980 nm激光激发下测得强的蓝色三光子上转换和近红外双光子上转换荧光. 宽的红外透过窗口、高的折射率和强的蓝色上转换荧光表明,Tm3+/Yb3+共掺铋碲酸盐玻璃有希望成为高效的上转换发光和激光材料.     

Yb3+/Er3+共掺锗碲酸盐玻璃上转换发光增强机理的研究

玻璃的最大声子能量决定稀土离子的上转换发光强度，但本研究发现：Yb^3 ／Er^3 共掺锗碲酸盐玻璃在980nm LD抽运下，上转换荧光强度随着Bi2O3对PbO的取代和碱金属离子半径的增大而明显增强．而Raman光谱显示基质玻璃的最大声子能量并不随Bi2O3对PbO的取代和碱金属离子半径的增大而变化，但玻璃的最大声子密度随着Bi2O3对PbO取代和碱金属离子半径的增大而降低．从玻璃无辐射跃迁概率的角度，通过分析表明，最大声子密度的降低是玻璃上转换发光强度增强的主要原因．     

卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃上转换发光研究

研究了卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃的热稳定性能、Raman光谱和上转换发光光谱,分析了Tm3+/Yb3+共掺氧卤碲酸盐玻璃的上转换发光机理.结果发现:混合卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃具有好的热稳定性能、低的声子能量、强的上转换蓝光.这表明混合卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃是一种上转换蓝光激光器的潜在基质材料.     

高光强激发下Er3+/Yb3+共掺TiBa玻璃的绿光上转换发光

制备了Er3+Yb3+共掺微米级高折射率TiBa玻璃颗粒和微球,玻璃基材主要成分为TiO2BaCO3Ba(NO3)2CaCO3SiO2等,掺入1mol%Er2O3+3mol%Yb2O3.用976nm激光激发测量了它们的上转换绿光发射,发现当抽运功率大于30mW(功率密度约为1000W·cm-2)时,524nm峰的强度大于547nm峰的强度,随功率的增大,其强度差越来越大,实验判断,这是由于材料吸收抽运光而升温所致 关键词： 上转换发光 掺Er3+Yb3+玻璃 微球     

Infrared to visible upconversion luminescence in Er3+/Yb3+ doped titanate glass prepared by containerless processing

Er³⁺ doped TiO₂–La₂O₃ glasses modified by ZrO₂ have been successfully fabricated by the containerless method with incorporated Yb³⁺ ions as sensitizers. Under the excitation of 980 and 808 nm diode lasers, visible emissions centered at 534, 554 and 674 nm are observed, which are assigned to the Er³⁺ transitions of ²H_11/2→⁴I_15/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2, respectively. The emission signals are so strong that they can be observed by naked eyes even at pumping power as low as 20 mW. Measurements of pump-power dependent intensity and time-resolved decay behavior of upconversion luminescence show that two-photon excited state absorption (ESA) and energy transfer (ET) between rare earth ions are the predominant mechanisms for upconversion emissions. Besides, the intensity of upconversion luminescence has been enhanced by increasing the concentration of ZrO₂ in these rare earth doped bulk titanate glasses.     

Ultraviolet and visible upconversion emission in Tb3+/Yb3+ co-doped fluorophosphate glasses

Ultraviolet and visible upconversion emissions in Tb³⁺/Yb³⁺ co-doped YF₃–BaF₂–Ba(PO₃)₂ glasses were observed under 980-nm laser diode excitation. The dependence of the emission intensities of Tb³⁺ on the pump power reveals that two-photon processes account for blue cooperative emission of Yb³⁺ at 476 nm and green upconversion emission of Tb³⁺ at 543 nm, and three-photon processes for ultraviolet emission of Tb³⁺ in the wavelength range of 379–435 nm. The effects of Tb³⁺ concentration on the emission intensity and the lifetime of Tb³⁺ and Yb³⁺ are investigated in detail. It is found that the cooperative energy transfer from a pair of excited Yb³⁺ ions to a ground Tb³⁺ ion is responsible for the appearance of blue and green upconversion emissions due to the ⁵D₄→⁷F _J (J=6,5,4,3) transitions of Tb³⁺, and the resonance energy transfer from Yb³⁺ to Tb³⁺ accounts for the population on the ⁵D₃,⁵G₆ level and ultraviolet upconversion emission.     

Sensitized thulium ultraviolet upconversion luminescence in Tm3+/Yb3+/Nd3+ triply doped nanoglass ceramics

Intense four- and five-photon ultraviolet upconversion processes through sensitization of Tm3+ ions in transparent SiO2-Al2O3-NaF-YF3 glass ceramics triply doped with Tm3+/Yb3+/Nd3+ under 796 nm excitation were investigated. Judd-Ofelt analyses evidenced the incorporation of rare-earth ions into the precipitated beta-YF3 nanocrystals. In contrast with the triply doped one, no ultraviolet upconversion luminescence was observed in the Tm3+/Nd3+ codoped glass ceramic, indicating that Yb3+ acts as bridging ions to enhance the energy transfer efficiency between Nd3+ and Tm3+. Based on the pumping power dependence of luminescence, upconversion mechanisms were proposed.     

Blue upconversion luminescence of CaMoO4:Li+/Yb3+/Tm3+ phosphors prepared by complex citrate method

Li⁺/Tm³⁺/Yb³⁺ co-doped CaMoO₄ upconversion (UC) phosphor was prepared by complex citrate-gel method and UC luminescence properties were investigated. Li⁺/Tm³⁺/Yb³⁺ co-doped CaMoO₄ has intense blue emission induced by ¹G₄??³H₆ transition at 476?nm that is improved 10 times more than that of Li⁺ undoped sample and weak red emission at 647 nm generated by ³F₂??³H₆ transition under excitation at 980?nm. The optimum doping concentration of Li⁺ ions was investigated and UC mechanism of Li⁺/Tm³⁺/Yb³⁺ co-doped CaMoO₄ was discussed in detail.     

Tm3+/Yb3+共掺碲铅锌镧玻璃的能量传递和上转换发光

制备了Tm3+/Yb3+共掺TeO2-PbO-ZnO-La2O3玻璃,研究了玻璃红外吸收光谱和980 nm激光抽运下上转换发光光谱,分析了上转换发光机制.基于Tm3+和Yb3+的能级图及上转换机制建立了速率方程,得出了稀土离子各能级的粒子数分布密度以及Tm3+与Yb3+之间的能量转移系数Cbi(i=0,1,3).结果表明,随着PbO加入,Yb3+:2F5/2与Tm3+:3H4间的能量转移不断增加,上转换蓝光的发光强度明显增强.     

Optical parameters and upconversion fluorescence in Tm3+/Yb3+ codoped tellurite glass

Tm³⁺/Yb³⁺ codoped tellurite glass has been prepared. Density, refractive index, optical absorption, Judd-Ofelt parameters and spontaneous transition probabilities of Tm³⁺ have been measured and calculated, respectively. Intense blue three-photon upconversion fluorescence and S-band (1470 nm) fluorescence were investigated under the excitation of a 980 nm diode laser at room temperature. Judd-Ofelt parameters, strong blue three-photon upcoversion emission of Tm³⁺ in glass indicate that Tm³+/Yb³⁺ codoped tellurite glass is a promising blue color upconversion optical and laser material. In addition, experiment results showed the 980 nm laser was more efficient than 808 nm laser when pumping Tm³⁺/Yb³⁺ codoped tellurite glass, Tm³⁺/Yb³⁺ codoped tellurite glass also could be a promising material for S-band amplification.     

Infrared-to-visible upconversion emission of Er3+/Yb3+-codoped SrMoO4 phosphors as wide-range temperature sensor

Er³⁺/Yb³⁺-codoped SrMoO₄ phosphors were prepared by a high-temperature solid-state reaction method. At room temperature, all the as-prepared samples exhibited strong upconversion properties and the emission intensity increased dramatically with the increase of Yb³⁺ ion concentration, reaching its maximum value when the concentration was 5 mol%. The dependence of emission intensity on the pump power suggested that the upconversion emission was a two-photon process. Furthermore, the optical temperature sensing properties based on green upconversion emissions of the SrMoO₄:0.01Er³⁺/0.05Yb³⁺ phosphor were studied. It is found that the SrMoO₄:0.01Er³⁺/0.05Yb³⁺ phosphor can be operated over a very wide temperature range of 93–773 K with a maximum sensitivity of ∼0.0128 K⁻¹, indicating that low- and high-temperature thermometry can be simultaneously realized in this phosphor.     

Nonlinear blue upconversion luminescence in Gd2O3: Er3+/Yb3+ nanowires

Gd₂O₃: Er³⁺/Y b³⁺ nanowires were prepared by a hydrothermal method. The upconversion luminescence was studied with 978-nm excitation. Ultraviolet and blue upconversion luminescence in which thermalization processes were involved, green and red upconversion luminescence were observed respectively. We analyzed the mechanism of upconversion luminescence. According to the ratio of ² H_11/2–⁴I_15/2 emission intensity to ⁴ S_3/2–⁴I_15/2 emission intensity, the temperature of the sample exposed to radiation of 978-nm laser was given.     

Er3+/Yb3+共掺Gd3Sc2Ga3O12晶体的上转换发光

研究了提拉法生长的Er3+/Yb3+:Gd3Sc2Ga3O12和Er3+:Gd3Sc2Ga3O12晶体在室温下320-1700 nm范围的吸收光谱和500-750 nm范围内的上转换荧光谱,同时对其上转换荧光的可能发生机制、途径以及上转换过程可能对Er3+的2.8 μm波段激光振荡产生的影响进行了分析和讨论.结果表明:Yb3+的敏化显著地增强了晶体在966 nm附近的吸收能力,大幅度加宽了晶体在该处的吸收带宽.在940 nm激光的激发下,Er3+/Yb3+:Gd3Sc2Ga3O12中的上转换荧光强度明显强于Er3+:Gd3Sc2Ga3O12中的上转换荧光强度,表明Yb3+与Er3+之间存在高效率的能量传递,其主要上转换机制可能为Yb3+-Er3+,Er3+-Er3+能量传递.