Spectroscopic properties and mechanism of Tm^(3+)/Er^(3+)/Yb^(3+) co-doped oxyfluorogermanate glass ceramics containing BaF_2 nanocrystals

Transparent Tm^3＋/Er^3＋/yb^3＋ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals are prepared. Under excitation of a 980-nm laser diode （LD）, compared with the glass before heat treatment, the Tm^3＋/Er^3＋/yb^3＋ co-doped oxyfluorogermanate glass ceramics can emit intense blue, green and red up-conversion luminescence and Stark- split peaks; X-ray diffraction （XRD） and transmission electron microscope （TEM） results show that BaF2 nanocrystals with an average diameter of 20 nm are precipitated from the glass matrix. Stark splitting of the up-conversion luminescence peaks in the glass ceramics indicates that Tm^3＋, Er^3＋ and （or） Yb^3＋ ions are incorporated into the BaF2 nanocrystals. The up-conversion luminescence intensities of Tm^3＋, Er^3＋ and the splitting degree of luminescence peaks in the glass ceramics increase significantly with the increase of heat treat temperature and heat treat time extension. In addition, the possible energy transfer process between rare earth ions and the up-conversion luminescence mechanism are also proposed.

Er^(3+)-Yb^(3+)双掺Li_2O-ZnO-SiO_2系透明玻璃陶瓷的制备及表征

采用熔融-晶化技术合成了Er3+-Yb3+掺杂的Li2O-ZnO-SiO2系(LZS)透明玻璃陶瓷。利用DTA,XRD,SEM,UV-Vis-NIR等对样品进行了表征,并分析了影响玻璃陶瓷析晶的因素。结果表明,LZS系玻璃具有良好的结晶性能,其最佳热处理温度为700℃,最佳热处理时间为50min,其主晶相为石英和Li8Zn10Si7O28。该玻璃陶瓷在可见光区的透过率可达85%。经SEM分析,粒子直径为30~40nm。荧光光谱显示,玻璃陶瓷的发射光谱较之基质玻璃有了极大的提高,而且在1530nm附近获得一较强发射峰。

Enhancement in Laser Performance of Er^(3+)/Yb^(3+) Co-doped Phosphate Glass Materials

Er3＋/Yb3＋co-doped phosphate are presented, laser glass materials with composition of P2O5-A12O3-Ba CO3-KNO3-Li2O-Zn O-Er2O3-Yb2O3（R-PABKLZ） are presented, in which an optimal molar ratio of 1：4 between Er3＋ and Yb3＋ was observed for achieving peak laser gain. Furthermore, due to adding 4.7 mol% Li1＋ and 4.6 mol% Zn2＋ ions into the glass, an optimum composition structure based laser material was demonstrated. On the other hand, since the high temperature melting method with changeable temperature control was used, the emission cross section of fl uorescence, excited lifetime, and an effective spectral half width reached 9.70 × 10-21 cm2, 8.20 ms, and 53.16 nm, respectively, so that a laser gain（semi× rad） of 103.05 was obtained, which is signifi cantly higher than previously reported results. The manuscript also argued the mechanism of relevant laser gain improvement.

Li^+共掺杂对Er^(3+)-Yb^(3+):TiO_2紫外、可见和红外发光同步增强研究(英文)

采用溶胶-凝胶(Sol-gel)法制备了Li+共掺杂的Er3+-Yb3+∶TiO2粉末。976 nm激光激发下在波长350~1700 nm范围内观察到了紫外、蓝色、绿色和红色上转换发光和红外下转换发光。随着Li+共掺杂浓度由0增大到20mol%,Er3+-Yb3+∶TiO2的紫外、可见和红外发光强度同步增强。低Li+共掺杂浓度引起的Li+固溶以及高Li+共掺杂浓度引起的相变过程相继破坏了Er3+的晶体场对称性,导致紫外、可见和红外发光显著增强。结果表明共掺杂Li+是一种提高Er3+掺杂材料发光性能的有效方法。

Er^(3+)-Yb^(3+)共掺杂ZrO_2-TiO_2粉末的上转换发光性质

通过共沉淀方法制备了Er3+和Yb3+共掺的ZrO2-TiO2上转换发光材料。用X射线衍射(XRD)对合成的物相结构进行了检测,并对样品在980 nm激光激发下的上转换发光性质进行了研究。观察到了位于528、550和662 nm附近的绿色和红色发光,分别对应于Er3+离子的2H11/2,4S2/3→4I15/2and4F9/2→4I15/2跃迁。样品的红光和绿光强度随着ZrO2和TiO2配比的变化而变化。随着烧结温度的升高,样品整体发光强度增加。讨论了上转换发光可能的机理:激发态吸收(ESA)和能量传递上转换(ET)过程。

Yb^(3+)掺杂对Er^(3+):NaYF_4上转换发光的调制作用

采用溶胶-凝胶(Sol-gel)法制备了2mol%Er3+、0,20和80mol%Yb3+共掺杂NaYF4上转换发光粉末.Er3+:NaYF4为α-NaYF4相和β-NaYF4相的混合结构,Yb3+共掺杂促进了β相到α相的转变.在976nm半导体激光器(LD)激发下获得了对应于Er3+的2 H11/2/4S3/2→4I15/2和4F9/2→4I15/2跃迁的绿色和红色上转换发光.随Yb3+掺杂浓度增大,绿色和红色上转换发光强度(Igreen和Ired)先增大后减小,强度比Igreen/Ired逐渐减小,对应2 H11/2/4S3/2→4I15/2跃迁的两个绿色上转换发光强度比(IH/IS)逐渐增加.表现为Er3+:NaYF4上转换发光随Yb3+浓度增大发生了调制,颜色由绿色逐渐变为黄色和红色.Yb3+掺杂对Er3+:NaYF4上转换发光的调制与Yb3+-Er3+间的能量传递紧密相关.

PbF_2:Er^(3+),Yb^(3+)荧光粉的制备和多波长响应双向转换发光机理（英文）

采用高温固相法制备了PbF_2∶Er^(3+),Yb^(3+)双向转换荧光粉。通过X射线粉末衍射分析(XRD)、结构精修分析、功率-强度测试和荧光光谱分析对样品进行了表征。通过X射线衍射和精修结果分析了样品的相组成和晶胞参数的变化。荧光光谱分析表明,在紫外光(378 nm)和不同波长的红外光(808、980、1 064和1 550 nm)激发下,样品在540～550 nm范围内具有强绿光发射和在650～660 nm范围内的弱红光发射。最后,通过强度-功率测试讨论了样品在不同波长的红外光下激发的上转换发光机理,并分析了在378 nm激发的下转换发光机理。

Preparation and characterization of Er^(3+)-Yb^(3+)-Ce^(3+) co-doped transparent glass ceramic containing nano Ca_5(PO4)_3F crystals

A transparent glass ceramic tri-doped with Ce3＋/Er3＋/yb3＋ was fabricated by the high-temperature melting technique and following heat-treatment. X-ray diffraction and transmission electron microscope results demonstrated that Cas（PO4）3F（FAP） nanocrystals, possessed with preferable emission performances for the 1.54 μm transition for doping Er3＋, were homogeneously pre- cipitated among the glass matrix with a mean size of 30 rim. Addition of Ce3＋ greatly enhanced 1.54 ~tm fluorescence of Er3＋ by the cross relaxation energy transfer between Er3＋ and Ce3＋. Meanwhile, incorporation of Ce3＋ dramatically decreased the visible upcon- version emission intensity of glass ceramic than that of glass, suggesting that Ce3＋ might incorporate into the FAP nanocrystals. The properties of this transparent glass ceramic showed the potential application as an efficient 980 nm pumped infrared laser medium.

Structural and optical studies of Yb^(3+),Er^(3+) and Er^(3+)/Yb^(3+) co-doped phosphate glasses

Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy. The absorption, emission spectra and fluorescence decay studies were carried out both at low and room temperatures. Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass. Up-conversion and cooperative fluorescence were also discussed.

Emissions of Er3+ and Yb3+ co-doped SrZrO3 nanocrystals under near-infrared and near-ultraviolet excitations

In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions under a near-ultraviolet(near-UV)excitation.The NCs were synthesized by the combustion method,and the as-synthesized NCs were post-annealed at high temperatures.The X-ray diffraction patterns revealed that the grain sizes and crystallinity degrees of the samples increased with increasing annealing temperatures.The photoluminescence spectra of our samples exhibited strong green and very weak red emissions with the near-UV excitation,originating from the f-f transitions in the Er3+ions.Interestingly,under near-infrared(near-IR)excitation,we identified sizable visible emissions at 525,547,and 660 nm in our NCs,which indicated that the UC process successfully occurred in our NCs.These UC emissions were maximized in the NCs with an Er3+concentration of 0.02 and thermal annealing at 1000°C.We found that the intensity ratios of red to green emissions increased with increasing annealing temperatures.We discussed the differences in the emissions between near-UV and near-IR excitations.

Silver nanoparticles enhanced near-infrared luminescence of Er^3＋/Yb^3＋ co-doped multicomponent phosphate glasses

A new way to improve the 1.53μm emission in Er3＋/Yb3＋ co-doped multicomponent phosphate glass was demonstrated by introducing silver nanoparticles （NPs） in rare-earth doped glass. The existence of Ag NPs was confirmed by absorption spectra and transmission electron microscopy （TEM） measurements. The homogeneous distribution of silver NPs could be observed by the TEM images. UV-Vis-NIR absorption spectra revealed that the surface plasmon band was centered at about 420 nm. The photoluminescence spectra of glass samples were used to investigate the effect of silver NPs on the fluorescence properties of Er3＋. Efficient 1.53μm emis-sion was obtained in prepared samples when pumped at 980 nm laser diode （LD）. The 1.53μm emission intensity could be enhanced 87% by doping 2 mol.% AgCl due to the increased localized field effect in the vicinity of NPs and the possible energy transfer from silver NPs to Er3＋ions. Our present work may point out one way to enhance the gain coefficient of Er3＋/Yb3＋ co-doped glass fiber.

Effect of concentration quenching on the spectroscopic properties of Er^(3+)/Yb^(3+) co-doped AlF_3-based glasses

A series of highly Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses have been investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and upconversion spectra have been performed to examine the effect of Er^(3+)/Yb^(3+) concentration quenching on spectroscopic properties. In the glasses with Er^(3+) concentrations below 10 mol%, concentration quenching is very low and the Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses have stronger fluorescence of 1.54μm due to the ~4I_(13/2)→~4I_(15/2) transition than that of Er^(3+) singly-doped glasses. As Er^(3+) concentrations above 10 mol% in the Er^(3+)/Yb^(3+) co-doped samples, concentration quenching of 1.54μm does obviously occur as a result of the back energy transfer from Er^(3+) to Yb^(3+). To obtain the highest emission efficiency at 1.54μm, the optimum doping-concentration ratio of Er^(3+)/Yb^(3+) was found to be approximately 1:1 in mol fraction when the Er^(3+) concentration is less than 10 mol%.

Er^(3+)-Yb^(3+) codoped borosilicate glass for optical thermometry

Infrared to green up-conversion emissions centered at the wavelengths of about 524 and 550 nm of the Er3+-Yb3+ codoped borosilicate glass are recorded,using a 978 nm semiconductor laser diode(LD) as an excitation source.The fluorescence intensity ratio(FIR) of the green up-conversion emissions at about 524 and 550 nm in the Er3+-Yb3+ codoped borosilicate glass has been studied as a function of temperature over the temperature range of 295-873 K.The maximum sensitivity and the temperature resolution derived from the FIR of the green up-conversion emissions are approximately 0.0038 K-1 and 0.2 K,respectively.It is demonstrated that the prototype optical temperature sensor based on the FIR technique from the green up-conversion emissions in the Er3+-Yb3+ codoped borosilicate glass plays a major role in temperature measurement.

Up-conversion emissions of Er^(3+)-Yb^(3+) codoped Al_2O_3 nanoparticles by the arc discharge synthesis method

The Er3+-Yb3+ codoped Al2O3 nanoparticles with an average particle size of about 50 nm have been synthesized by an arc discharge synthesis method. The green and red up-conversion emissions centered at about 526, 547 and 677 nm, corresponding respectively to the 2H11/2→4I15/2, 4S3/2→4I15/2 and 4 F9/2→4I15/2 transitions of Er3+, were detected by a 978-nm semiconductor laser diode excitation. The Annealing has evident effect on the up-conversion emissions of the samples: The red up-conversion emission is noticeable before annealing; however, the green up-conversion emission becomes predominant after annealing. The mixture of (Er,Yb)3Al5O12 and α-(Al,Er,Yb)2O3 phases is more favorable for green up-conversion emissions due to an enhancement of the ESA (I) of 4I11/2+a photon→4F7/2 and ET (III) of 2F5/2(Yb3+)+4I11/2(Er3+)→2F7/2(Yb3+)+4F7/2(Er3+) processes. The two-photon absorption up-conversion process is involved in the green and red up-conversion emissions. The results have proved that arc discharge synthesis is a new promising preparation technology for optical materials.

Investigation of Silver Nanostructures and Their Influence on the Fluorescence Spectrum of Erbium-Doped Glasses

Sodium borate glasses embedded with silver were made by the melt quenching technique. Glass transition temperature was recorded by thermal analysis of the sample. As made glasses revealed emission in the visible region under nitrogen laser and excimer laser excitations. Heat treatment was used to induce silver metallic particles. Absorption spectra revealed a peak at 417 nm due to surface Plasmon resonance. Particle size was estimated to be 2.6 ± 0.2 nm. Erbium and silver co-doped multielement oxide glasses were made by the melt quenching technique followed by heat treatment to induce nanoparticles. In heat treated samples, Er3+ luminescence increased 4× due to enhanced field in the vicinity of silver particles. Under excimer laser excitation, Er3+ and 2% Ag co-doped glass revealed Er3+ transitions due to enhanced field at the rare-earth ions. Under 795 nm laser excitation Er3+ green upconversion signals are found to be 4× stronger in 2% Ag co-doped, heat treated sample, than the others.

Multiphoton process and optical amplification in Er^(3+)-Yb^(3+)-doped fiber pumped by Ti:Al_2O_3 tunable laser at 980-nm band

The .Er3+-Yb3+-doped fiber has a broadened absorption spectrum, which means the pumping sources can work efficiently from 810 to 1100nm. Among them 980nm is the maximum.absorption （10 dB/km） wavelength. By energy transferring and multiphoton process, the visible and ultraviolet radiation occurs when the Er3+-Yb3+-doped fiber is pumped by the laser at 980-nm band. Further researches on the mechanism of the fluorescence of Er3+-Yb3+-doped silica fiber pumped by Ti: A12O3 tunable laser at 980-nm band are helpful

An investigation on the magneto-optic properties of terbium gallium garnet under high magnetic field

This paper reports that a series of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J-O intensity parameters Ωk （k = 2, 4, 6）, spontaneous radiative lifetime Trad, spontaneous transition probability A, fluorescence branching ratio β and oscillator strength fed of the Nd3＋ ions at room temperature are calculated based on Judd-Ofelt （J-O） theory. The temperature dependence of the up-conversion photoluminescence characteristics in a Nd3＋：Er3＋：Yb3＋ co-doped sample is studied under a 978 nm semiconductor laser excitation, and the energy transfer mechanisms among Yb3＋, Er3＋ and Nd3＋ ions are analysed. The results show that the J-O intensity parameters Ω2 increase when the Nd3＋ concentration of the Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses increases. The possibility of spontaneous transition is small and lifetimes are long at levels of 4F5/2 and 4F3/2. The intensity of Nd3＋ emissions at 595, 691, 753, 813 and 887 nm axe markedly enhanced when the sample temperature exceeds 400 K. The reasons being the cooperation of the secondary sensitization from Era＋ to Nd3＋ and the contribution of a multi-phonon.

基于Er-Yb共掺杂硼硅酸盐玻璃的光学温度传感

采用978nm激光二极管泵浦Er-Yb共掺杂硼硅酸盐玻璃,获得中心波长约为524和550nm的绿色上转换发光,在295-873K范围内,研究了Er-Yb共掺杂硼硅酸盐玻璃的524和550nm的荧光强度比和温度的函数关系,得到的最大灵敏度和温度分辨率分别约为0.0038K-1和0.2K.结果表明基于Er-Yb共掺杂硼硅酸盐玻璃绿色上转换发光的荧光强度比技术的光学温度传感样品在温度测量方面具有一定的应用潜力.