Enhancement of upconversion luminescence due to the formation of nanocrystals in Er~(3+)-doped tellurite glasses

Optically transparent Er3 -doped tellurite-based nanocrystallized glasses with the composition of 70TeO2·15Li2O·15Nb2O5·0.5Er2O3 (mol) have been prepared by a conventional melting quenching and the subsequent heat treatment processes. The sizes of grown nanocrystals in glass matrix appear to be 35-50 nm from the X-ray diffraction (XRD) measurement. The microhardness measurement shows that the Vickers hardness values of the nanocrystallized tellurite glasses are larger (33%-62%) than those in the base glass. The Raman spectra imply that the maximum phonon energy of the based glass decreases and shifts from 668 to 638 cm-1 after heat-treatment. Visible upconversion luminescence and infrared luminescence of the base glass and heat-treated glasses under 980-nm laser diode (LD) excitation are investigated. The 524-, 546- and 656-nm upconversion intensities by 980-nm pumping increase significantly.     

离子凝聚法制备负载流感疫苗的壳聚糖微球

采用三聚磷酸钠(TPP)作为离子交联剂, 应用离子凝聚法制备负载流感疫苗的壳聚糖微球. 筛选出壳聚糖起始质量分数为1%. TPP的浓度对壳聚糖微球的制备影响较大, 采用低浓度的TPP(200 μg/mL)制备的微球放置过夜均出现沉淀现象, 高浓度的TPP(800 μg/mL)在制备过程中出现絮状沉淀. 固化比影响微球的释放行为, 固化比为1∶1的微球爆炸式释放率达到90％, 固化比为1∶3的微球6 h后逐步释放, 12 h后释放率达到95％. 固化比为1∶5的微球6 h后没有明显的释放行为. 壳聚糖溶液的pH对微球的制备和释放没有显著的影响. 通过对负载流感疫苗的壳聚糖微球的制备条件和释放行为的研究结果表明, pH=5.6的壳聚糖溶液, 固化比为1∶3, TPP的质量浓度为400 μg/mL是较理想的流感疫苗壳聚糖微球的制备条件.     

铈离子价态和OH~-根浓度对Tb~(3+)掺杂磷酸盐玻璃发光性能的影响

通过控制熔制气氛获得了Ce/Tb离子共掺磷酸盐玻璃样品,利用吸收光谱判断Ce离子在玻璃中的价态,并研究了不同Ce离子价态下的激发光谱和发射光谱,进而分析了Ce离子价态对Tb3+离子发光性能的影响。通过除水工艺的控制,获得不同OH-根浓度的Ce/Tb离子共掺磷酸盐玻璃样品,研究了OH-根浓度对Tb3+离子发光性能的影响。结果表明,在Ce/Tb离子共掺磷酸盐玻璃中,采用还原气氛熔制和通气除水工艺,可大大提高Tb3+离子在545 nm处的发光强度。     

聚氨酯制备的多尺度模拟方案

针对聚氨酯材料特性设计了多尺度计算机模拟方案, 并研究了不同原料及相同原料但不同官能度对所制备的聚氨酯材料力学性能和玻璃化转变温度的影响. 基于原子级别的结构, 建立了耦合聚合反应的粗粒化耗散粒子动力学模型来描述组分扩散及交联网络结构的形成过程. 并反映射这个粗粒化结构到全原子级别来分析材料的力学性能和热力学性能. 这个多尺度研究方案也可推广到研究多个竞争性因素同时主导的复杂体系中.     

Brillouin gain spectrum characterization in Ge-doped large-mode-area fibers

The dependence of Brillouin gain spectrum (BGS) characteristics, including the Brillouin frequency shift (BFS) and the BGS bandwidth, on germanium concentration in large-mode-area Ge-doped passive fibers is investigated theoretically and experimentally. The simulation results show that the BFS is inversely proportional to GeO₂ concentration, and the BGS bandwidth initially increases with the augment of GeO₂ concentration, and then decreases. The BGSs of four fibers with core diameters of 10 μm and 20 μm for different GeO₂ concentrations are compared experimentally. Experimental results demonstrate that with the same core diameter, the variations of BFS and BGS bandwidths with GeO₂ concentration accord with the simulation results. Additionally, the BGS characteristics of three large-mode-area passive fibers with diameters of 10 μm, 25 μm, and 30 μm are measured, which confirm that the increasing of the fiber diameters will cause the BGS bandwidth to broaden. We believe that these results can provide valuable references for modulating the high-power narrow-linewidth fiber lasers and Brillouin fiber amplifiers.     

Large-mode-area neodymium-doped all-solid double-cladding silicate photonic bandgap fiber with an index step of ～0.5%

A large-mode-area neodymium-doped silicate photonic bandgap fiber was theoretically designed and experimentally demonstrated. The relative index step between the high-index rods and the background glass was ～0.5%,which is the lowest cladding index difference reported on rare-earth-doped all-solid photonic bandgap fibers to our knowledge. An output power of 3.6 W with a slope efficiency of 31% was obtained for a 100-cm-long fiber.     

氟氧化物纳米相玻璃陶瓷Tb(0.7)Yb(5)∶FOV的合作下转换发光

报道了氟氧化物纳米相玻璃陶瓷Tb(0.7)Yb(5)∶FOV的红外量子剪裁研究,测量了从可见到红外的荧光发光光谱、激发谱、和荧光寿命,分析了{1([5 D4→7 F6](Tb3+),2([2 F7/2→2 F5/2] (Yb3+)}的红外量子剪裁现象,发现了487.0nm光激发5 D4能级和378.0nm光激发(5 D3,5 G6)能级的理论量子剪裁效率ηx％Yb依次分别为121.35％和136.27％.首次发现了一种新颖的合作(共协)下转换发光现象{2([(5 D3,5 G6)→5 D4](Tb3+),1([2 F7/2→2 F/2](Yb+)},即首次发现施主Tb3+离子释放两个小能量光子[(5 D3,5 G6)→5 D4]的能量,导致出现一个受主Yb3+的[2 F5/2→2 F7/2]的中等能量的光子.     

Nd~(3+)/Yb~(3+)共掺磷酸盐玻璃光纤的发光与激光特性研究

以970 nm和808 nm半导体激光器作为抽运源,从光纤长度和抽运功率两个方面,探讨了Nd~(3+)/Yb~(3+)摩尔浓度比约为4:1的共掺磷酸盐玻璃光纤的发光与激光特性.在970 nm抽运下,光纤光谱以Yb~(3+)离子的发光为主,但Yb~(3+)→Nd~(3+)能量传递会对光纤光谱(激光和受激放大自发辐射)产生调制作用,调制作用随970 nm抽运功率或光纤长度的增加而显著,甚至出现显著的双波长激光现象.尽管玻璃样品中Nd~(3+)→Yb~(3+)的能量传递效率ηNd→Yb高达64%,但在808 nm抽运下,激光峰始终在1053 nm附近产生,且与808 nm抽运功率大小和光纤长度无关.为解释这一现象,推导了考虑Nd~(3+)离子受激辐射的能量传递模型.从理论模型来看,Nd~(3+)→Yb~(3+)能量传递作用随Nd~(3+)离子受激辐射信号光强度的增加而迅速减弱,这与该光纤实际测试的荧光光谱随808 nm抽运功率的变化规律相符合.因此,当采用Nd~(3+)离子来敏化Yb~(3+)离子时,需要考虑Nd~(3+)离子的受激辐射对Nd~(3+)→Yb~(3+)能量传递的抑制作用.     

Nd3+-doped silica glass and fiber prepared by modified sol-gel method

Large-size Al³⁺/Nd³⁺co-doped silica glass with 5000 ppm Nd³⁺and 50,000 ppm Al³⁺doping concentrations was prepared by the modified sol-gel method combined with high-temperature melting and molding technology. Electron probe microanalyzer tests indicated that high doping homogeneity was achieved with this sample preparation method. The spectral properties of the Nd³⁺ions were evaluated. Nd³⁺-doped silica fiber(NDF) with a core-to-cl...     

Bi掺杂高磷石英基光纤实现E波段放大

采用改进的化学气相沉积技术结合液相掺杂工艺制备了低损耗Bi掺杂高磷石英基光纤,P2 O5摩尔分数高达7.2％,光纤的背景损耗为18 dB/km@1550 nm.进一步采用1240 nm的可调谐拉曼激光器泵浦自制Bi掺杂高磷石英基光纤,在1355～1380 nm波段实现净增益,在1355 nm波长处的最高增益为5.14 ...