Yb^(3+)/Nd^(3+)掺杂对Sr_(9)Ga(PO_(4))_(7)∶Cr^(3+)发光性能的影响

近红外荧光粉由于其独特的物理特性和广阔的应用前景吸引了人们极大的研究兴趣。本文通过高温固相反应法合成Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+)近红外荧光粉,使用460 nm蓝光激发样品的发射波长位于833 nm,半峰宽为117 nm。随后引入稀土离子合成Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),Yb^(3+)和Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),Nd^(3+)近红外荧光粉。相比Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),460 nm蓝光激发的Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),Yb^(3+)同时出现Cr^(3+)和Yb^(3+)特征发射峰,经过光谱分析和荧光寿命变化证明Cr^(3+)-Yb^(3+)存在能量传递通道,最高使Cr^(3+)-Yb^(3+)能量传递效率达80.2%,得益于Yb^(3+)卓越的热稳定性促使整体荧光光谱热稳定性提高约3.7倍。设计合成的Sr_(9)Ga(PO_(4))_7∶0.8Cr^(3+),Nd^(3+)样品调制出833,876,1 060 nm的多峰发射,显著拓宽了近红外光谱范围。最终,讨论了荧光粉在温度传感和无损检测领域的应用,证明该系列荧光粉具有广阔的应用前景。

Nd^(3+)/Yb^(3+)掺杂YNbO_4粉末上转换发光特性

采用高温固相法,以50Nb_2O_5-40Y2O_3-2Nd2O_3-8Yb_2O_3的量比在1 300℃下制备Nd^(3+)/Yb^(3+)掺杂YNbO_4粉末样品。运用Judd-Ofelt理论研究样品光谱特性。由吸收谱中各吸收峰面积计算得到谱线强度参数Ωλ(λ=2,4,6),进而得出理论振子强度及实验振子强度,二者均方根偏差δ_(rms)=1.618×10-7。计算了Nd^(3+)能级4F3/2→4IJ'(J'=15/2,13/2,11/2,9/2)跃迁几率、跃迁分支比和能级寿命。4F3/2→4I11/2跃迁分支比最高(56.91%),对应波长1 062 nm。且亚稳态4F3/2能级寿命较长,为1.435 2 ms,适合作为上转换中间能级。在980 nm半导体激光器激发下,观测到波长为487,541,662 nm上转换发光,分别对应于Nd^(3+)的2G9/2→4I9/2、4G7/2→4I9/2和4G7/2→4I13/2辐射跃迁。通过样品上转换发射功率与激光器工作电流进行的曲线拟合,得到吸收光子数目依次为2.06,1.99,2.15,确定3个发射峰均对应于双光子吸收。

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.

Nd^(3)+:YAG-Al_(2)O_(3) nanocrystalline transparent ceramics with high inflexion concentration quenching of Nd^(3+) prepared by amorphous crystallization

Rare earth ion-doped Y_(3)Al_(5)O_(12)(YAG)-based transparent ceramics have been used as important laser gain media for a long time,yet the doping concentration of active ions is limited due to concentration quenching,wherein the inflexion concentration quenching of Nd^(3+)is recognized as 1.0 at%.In this work,YAG-Al_(2)O_(3) nanocrystalline transparent ceramics with a concentration of Nd^(3+)(O-5.0 at%)were fabricated via amorphous crystallization,and the crystal structure evolution,morphology,and optical properties were systematically investigated by differential scanning calorimetry(DSC),X-ray powder diffraction(XRD),transmission electron microscopy(TEM),magnetic resonation(MAS),nuclear magnetic resonation(NMR),and fluorescence spectroscopy.The doping of Nd^(3+)can promote the transition of Al[5]and Al[6]to Al[14],indicating improvements in the ability of the amorphous material to form Nd^(3+):Y_(2)O_(3)-Al_(2)O_(3) vitrified beads,and 1.5 at%Nd^(3+):YAG-Al_(2)O_(3) nanocrystalline transparent ceramics can be obtained by crystallization at 1050℃ with a matrix composed of YAG and concomitant δ-Al_(2)O_(3) and θ-Al_(2)O_(3).The nanocrystalline transparent ceramics show an internal transmitance of 89.56%at 1064 nm,and the strongest emission peak corresponds to the energy transfer from 4F_(3/2) to 4l_(11/2) of Nd^(3+)with a fluorescence lifetime of 231μs when pumped by an 808 nm laser.Specifically,spectral broadening begins to occur,indicating the onset of concentration quenching,when the concentration of Nd^(3+)exceeds 1.5 at%,substantially higher than the 1.0 at% observed in YAG ceramics.YAG-Al_(2)O_(3) nanocrystalline transparent ceramics obtained by amorphous crystalization can be utilized as the matrix to increase the inflexion point of doping concentration quenching of Nd^(3+),and this material may have great potential as a laser gain medium.

Spectroscopic properties and energy transfer of Nd^(3+)/Ho^(3+)-doped Ga_2O_3-GeO_2 glass by codoping Yb^(3+) ion

This study presented the luminescence properties of Nd^3＋/Yb^3＋/Ho^3＋ dopant ions inside a host based on Ga_2O_3-GeO_2-Li_2O（GGL） glass. The measured differential scanning calorimetry result showed that GGL glass exhibited excellent stability against devitrification with ？T=135 oC. Obvious 543 and 657 nm emissions were observed in Nd^3＋/Ho^3＋-codoped sample. The incorporation of Yb^3＋ into Nd^3＋/Ho^3＋-codoped glass system had resulted in enhanced upconversion emission intensity under the excitation of 808 nm and/or 980 nm laser diode（LD）. The possible mechanisms and related discussions on this phenomenon were presented. It was noted that the presence of Yb^3＋ yielded an enhancement about 7 and 11 times in the 543 and 657 nm emission intensities respectively under 808 nm excitation due to the energy transfer from Nd^3＋ to Ho^3＋ via Yb^3＋ ion. Here Yb^3＋ played a major role as a bridging ion. While enhanced 543 and 657 nm emission intensities under the excitation of 980 nm LD originated from the sensitization effect of Yb^3＋. Our results showed that Nd^3＋/Ho^3＋/Yb^3＋ triply doped GGL glass might be a promising candidate for the development of visible-laser materials.

重频纳秒大能量激光增益介质初探

重频纳秒大能量激光器在科研探究、工业制造、军事防务等领域发挥着重要作用,本文详细介绍了Yb^(3+)或Nd^(3+)稀土离子掺杂的激光晶体、激光玻璃和激光陶瓷的研究进展以及相应的重频纳秒大能量激光器代表性成果,分析了激光增益介质发射截面、热导率、上能级寿命等参数特性对激光系统的影响。针对重频纳秒大能量激光器增益介质的选择制备、热管理、自发辐射放大效应管控展开讨论并梳理解决对策,对其未来的发展前景进行了展望。

Gain Properties of Triply-Doped Graphene-Insulator-Graphene Nanosheet Waveguide

Er^(3+)-Tm^(3+)-Pr^(3+)triply-doped graphene-glass-graphene(GGG) nanosheet waveguide amplifier, which is a promising candidate for integrated photonic devices, is modelled and numerically analyzed. The designed waveguide is composed of a triply-doped tellurite glass core. The core is sandwiched between two graphene layers.The rate and power propagation equations of a heterogeneous multi-level laser medium are set up and solved numerically to study the effects of waveguide length and active ion concentrations on amplifier performance at five different input signal wavelengths(1.310, 1.470, 1.530, 1.600 and 1.650 μm). The analytical results show that rareearth ion dopant concentrations at an order of 10^(26) ion/m^3, waveguide length at 0.1 m and pump power at 100 m W can amplify 1.530 and 1.600 μm input signals with 1 μW power up to approximately 20.0 and 24.0 dB respectively.Finite-difference time-domain(FDTD) simulation results show that mode field radius of GGG waveguide is smaller than that of silicon waveguide. Consequently, GGG waveguide with the same pump and signal power and the same gain-medium length can produce higher gain than silicon waveguide.