Yb3+掺杂锂硅酸盐玻璃的近红外发光特性

为了研制高功率光纤激光器的掺镱纤芯材料,采用高温熔融法制备了0.70SiO₂-0.18Li₂CO₃-0.04MgCO₃-0.04BaCO₃-0.02Al₂O₃-0.02Yb₂O₃（摩尔分数）锂硅酸盐玻璃样品,测试了其吸收光谱和858nm激发下的荧光光谱,进一步对光谱和激光性能参量进行了理论计算。结果表明,样品的主荧光峰位于1036nm附近,荧光有效线宽为94.1nm,吸收截面为1.143pm2,发射截面为1.024pm2,荧光寿命为0.98ms,激发态最小的粒子数仅为0.042,最小抽运强度为0.76kW·cm-2。与近年来相关文献中报道的镱掺杂玻璃相比,该掺镱锂硅酸盐玻璃在光谱及激光性能上比较有优势,有望在研制镱掺杂光纤中得到应用。     

光学碱度与能量传递对Bi/Yb3 共掺杂锗酸盐玻璃近红外发光性质的影响

采用传统高温熔融法制备了Bi/Yb3 共掺杂锗酸盐玻璃,通过测试吸收光谱、近红外光谱和荧光衰减寿命,研究了玻璃样品的近红外发光性质。在980nm 或808 nm 激光激发下,均能同时观察到Yb3 和Bi离子的近红外发光,这一结果表明,Yb3 离子与Bi离子之间存在相互能量传递。随着Yb3 离子浓度的增加,玻璃基质的光学碱度和Yb3 离子到 Bi 离子的能量传递效率均增加,讨论了能量传递效率的提高对Bi离子发光的增强作用与光学碱度增加对Bi离子发光的削弱作用的竞争影响机制,获得了Bi/Yb3 近红外发光的机理。     

Er^3＋,Yb^3＋掺杂氟氧化物微晶玻璃上转换发光的研究

测量了Er^3 掺杂氟氧化物微晶玻璃、Er^3 ,Yb^3 掺杂氟氧化物微晶玻璃退火前后3种样品的吸收光谱、激发光谱、上转换发光光谱及其强度随泵浦光强的变化,对比讨论了其上转换发光特性。     

超宽带发光铋掺杂玻璃及光纤的研究进展(特邀)

自诺贝尔奖获得者高锟提出可用玻璃光纤代替传统电缆传输线,利用光波导传输光信号的方法来实现信息传输以来,人们就一直致力于优化现有光纤的性能和探索新的光纤激光介质材料。目前,用于光通信系统的光纤激光器和光放大器的增益光纤多见于稀土离子掺杂玻璃光纤,然而稀土离子固有的f-f跃迁导致较窄的传输带宽已经无法满足日益剧增的网络数据传输需求。铋(Bi)离子是继过渡金属离子、稀土离子后的第三类激活离子,是激光材料领域发展的新方向。目前,Bi掺杂玻璃光纤已经在1 150～1 550 nm和1 600～1 800 nm范围内实现了激光输出和光信号放大。这充分说明了Bi掺杂玻璃光纤有望解决现有数据传输能力不足的问题,成为新一代光纤激光器和放大器的增益材料。因此,文中主要介绍Bi掺杂玻璃和光纤的研究进展,分析Bi掺杂玻璃及光纤材料目前存在的问题,并展望了未来的研究方向。     

Eu3+掺杂GdPO4微晶玻璃的制备及其发光特性的研究

采用高温熔融法,制备了摩尔组分为53P2O5-16BaO-9Na2O-7K2O-14.25Gd2O3-0.75Eu2O3系统基质玻璃,熔化温度为1 400℃,经过热处理后获得微晶玻璃。采用X射线衍射(XRD)、扫描电镜(SEM)和荧光光谱,对微晶玻璃的结构、形貌和发光性能进行研究。XRD结果表明,基质玻璃经过700℃、800℃热处理2h得到Eu3+掺杂GdPO4微晶玻璃,其晶粒尺寸分别约为39nm和55nm;荧光光谱研究结果表明,与基质玻璃相比,微晶玻璃的激发强度和发射强度明显增强,微晶玻璃中源自Eu3+的7F0-5L6跃迁强度与电荷迁移带强度的比值降低,发射峰出现明显劈裂,且5D0-7F2与5D0-7F1跃迁强度的比值减小,表明Eu3+成功地进入了GdPO4晶相中。微晶玻璃中,Eu3+发射强度和激发强度随着热处理温度的升高而增强。     

980nm半导体激光器激发下Er3+,Yb3+共掺杂氟氧化物微晶玻璃的上转换发光

测量了Er^3 ,Yb^3 掺杂氟氧化物微晶玻璃的吸收光谱、激发光谱、上转换发光、光谱及其强度随泵浦光强的变化,讨论了其上转换发光特性。     

Er~(3+),Yb~(3+)掺杂氟氧化物微晶玻璃上转换发光的研究

测量了 Er3+掺杂氟氧化物微晶玻璃、Er3+ ,Yb3+掺杂氟氧化物微晶玻璃退火前后 3种样品的吸收光谱、激发光谱、上转换发光光谱及其强度随泵浦光强的变化 ,对比讨论了其上转换发光特性     

Ho3+/Yb3+共掺的SiO2-Al2O3-BaO-BaF2微晶玻璃上转换发光研究

制备了Ho3+/Yb3+共掺的氧氟硅酸盐玻璃, 根据玻璃样品的差热分析进行微晶化处理, 测试了Ho3+/Yb3+共掺微晶玻璃的X射线衍射(XRD)图谱、吸收光谱和上转换发光光谱。结果发现, 在980 nm LD激发下, Ho3+/Yb3+共掺的含BaF2纳米晶的氧氟硅酸盐微晶玻璃可以同时观察到绿光(544 nm)和红光(656, 748 nm)上转换发光, 分别对应于Ho3+ 离子的5F4/5S2→5I8, 5F5→5I8和5F4/5S2→5I7能级跃迁, 与未热处理的玻璃样品相比, 微晶玻璃样品的绿光发光强度增强约347倍。研究结果表明含BaF2纳米晶的氧氟硅酸盐微晶玻璃是一种潜在的上转换基质材料。     

Sm3+离子掺杂对BaGa2O4∶Cr3+近红外长余辉发光的增强研究

利用高温固相法制备了BaGa₂O₄∶Cr³⁺,Sm³⁺(BGO∶Cr,Sm)近红外长余辉发光(PersL)材料,考察了Sm³⁺掺杂浓度和煅烧温度对BGO∶Cr,Sm晶体结构和发光性能的影响,初步探讨了近红外余辉发光机理。结果表明：当长余辉发光材料组成为BGO∶Cr_0.06,Sm_0.004且煅烧温度为1100℃时,可以获得高纯度的BGO∶Cr,Sm长余辉发光材料,其发射波长为734 nm。Cr³⁺与Sm³⁺共掺杂为应用于生物成像的BGO提供了优化策略,同时为开发长余辉发光材料提供了良好范例。     

Viscosity of GeO2-doped silica glasses

The viscosity of GeO₂-doped silica glasses is experimentally evaluated and found to be expressed as a function of the monoexponential form η₀ exp(-AΔe), where η₀ is the viscosity of pure silica glass, A is a positive constant, and Δe is an equivalent relative-index difference that is introduced for a silica glass with nonuniform dopant distribution in its cross section. The constant A for GeO₂-doped silica glasses is found to be about 0.5, which is much smaller than that for fluorine-doped silica glasses and has almost no temperature dependence between 1400°C and 2200°C     

用于白光LED的红色荧光粉SrAl2Si2O8:Eu3+,Li+的制备和发光性能研究

采用高温固相法制备了Sr1－x Al₂Si₂O₈:Eu³⁺ x,Li⁺0.03系列红色荧光粉,研究了试样的晶体 结构和发光性质。合成的试样均为纯相的SrAl₂Si₂O₈晶体,单斜晶系,空间群为 C2/m(12); Eu³⁺和Li⁺进入基质晶体中,使得SrAl₂Si₂O₈晶胞参数a、b和c 略微减小,只引起了晶体结构轻 微的畸变。试样的激发光谱由位于220~580nm波长的一个宽激发带 和一组锐线峰构成,其中 395nm波长处Eu³⁺的⁷F₀→⁵L₆激发峰的强度最强。发射光谱位于550~750nm波长范围内呈现多 条锐 线发射,其中595nm和615nm波长处发射峰最 强,分别归属于Eu³⁺的⁵D₀→⁷F₁磁偶极跃迁和⁵D ₀→⁷F₂电偶极跃迁。研究了Eu³⁺浓度对荧光粉发光性能的影响, 结果表明,随着Eu³⁺浓度的增 加,发光强度先增加后减小,最佳掺杂量为0.03,而对试样的色坐标 几乎没有影响;该系列荧光粉浓度淬灭机理为电偶极–电偶极(d-d)相互作用。     

Chemical nature of the passivation layer depending on the oxidizing agent in Gd2O3/GeO2/Ge stacks grown by molecular beam deposition

In Ge-based metal oxide semiconductor technology, the insertion of a passivation layer seems to be crucial in unpinning the Fermi level at the interface and in reducing the amount of interface defects. GeO₂ was obtained by atomic oxygen (AO), molecular oxygen or ozone chemisorption. Atomic or molecular oxygen was used in the deposition of Gd₂O₃. Gd₂O₃ thin films were grown by molecular beam deposition directly on (1 0 0) Ge or on a GeO₂ interlayer. The chemical nature of the Gd₂O₃/Ge interface was characterized by time-of-flight secondary ion mass spectrometry depth profiles. Without GeO₂ layer Gd and Ge interdiffusion is observed and the concomitant formation of GeOGd bonds is also supported by X-ray photoelectron spectroscopy energy shift at the Ge 3d peak and by a singularity in the interface defect energy distribution at ∼0.48 eV. Further, depending on the GeO₂ formation process, the profile shape of Ge and O related secondary ions at the GeO₂/Ge interface can be related with a defective Ge region close to the GeO₂/Ge. In particular, considering the ratio between Ge and GeO₂ related secondary ion signals, the interlayer passivated using AO turns out to be comparatively enriched in Ge, while the use of ozone for GeO₂ formation leads to a Ge deficient layer.     

Low Rayleigh scatteringP2O5-F-SiO2 glasses

The Rayleigh scattering and infrared absorption losses of P₂ O₅-F-doped silica glass, which is a candidate material for ultra-low-loss optical fiber, were investigated experimentally. The Rayleigh scattering loss of 8.5 wt.% P₂O₅ and 0.3 wt.% F-doped SiO₂ glass is found to be 0.8 times that of pure silica glass. It is also found that the infrared absorption property of P₂O₅-F-SiO₂ glass is almost the same as that of pure silica glass. The minimum loss for the proposed composition is estimated to be 0.11 dB/km at 1.55 μm wavelength, and 0.21 dB/km at 1.3 μm wavelength     

Structural properties of V2O5 thin films prepared by vacuum evaporation

Vanadium pentoxide (V₂O₅) films were deposited on glass substrates by vacuum evaporation technique at various deposition temperatures (T_s) viz., 300, 473, 573, 623 and 673 K. The structural and microstructural properties of the films are analyzed using XRD and Raman scattering measurements. X-ray characterization revealed the films deposited at T_s473 K are amorphous and the film deposited at T_s573 K are polycrystalline with orthorhombic symmetry. The corrected lattice constant values are determined from Nelson-Riely plots. The lattice constants “a” and “c” are found to decrease with increase in the deposition temperature, which may be attributed to the increase in non-stoichiometry. Change in the preferred orientation is observed for films deposited at substrate temperatures 623 K which is likely to be governed by the recrystallization process. Various structural parameters such as lattice constants, grain size, and microstrain and dislocation density are determined and the influence of deposition temperature on the structural parameters are discussed.     

Concentration-dependent luminescence properties in Er3+-doped TeO2-ZnO-La2O3 glasses

Erbium-doped tellurite-based glasses(Er3+:TeO2-ZnO-La2O3) are prepared by the conventional melt-quenching technique,and concentration-dependent luminescence properties of Er3+ are investigated.A significant spectral broadening of the 1.53 μm fluorescence corresponding to 4I13/2 →4I15/2 transition is observed,and the fluorescence decaying becomes a nearly exponential way with the increasing Er3+concentration.Radiation trapping is evoked to explain the broadening of 4I13/2 → 4I15/2 emission line of Er3+ ions.The optimum doping content of Er2O3 for 1.53 μm fluorescence emission is about 1.5 mol%.     

Towards metal electrode interface scavenging of rare-earth scandates: A Sc2O3 and Gd2O3 study

Amorphous Gd₂O₃ and Sc₂O₃ thin films were deposited on Si by high-pressure sputtering (HPS). In order to reduce the uncontrolled interfacial SiO_x growth, firstly a metallic film of Gd or Sc was sputtered in pure Ar plasma. Subsequently, they were in situ plasma oxidized in an Ar/O₂ atmosphere. For post-processing interfacial SiO_x thickness reduction, three different top metal electrodes were studied: platinum, aluminum and titanium. For both dielectrics, it was found that Pt did not react with the films, while Al reacted with them forming an aluminate-like interface and, finally, Ti was effective in scavenging the SiO₂ interface thickness without severely compromising gate dielectric leakage.     

Bidirectional rectifier with gate voltage control based on Bi2O2Se/WSe2 heterojunction

Two-dimensional (2D) WSe₂ has received increasing attention due to its unique optical properties and bipolar behavior. Several WSe₂-based heterojunctions exhibit bidirectional rectification characteristics, but most devices have a lower rectification ratio. In this work, the Bi₂O₂Se/WSe₂ heterojunction prepared by us has a type Ⅱ band alignment, which can vastly suppress the channel current through the interface barrier so that the Bi₂O₂Se/WSe₂ heterojunction device has a large rectification ratio of about 10⁵. Meanwhile, under different gate voltage modulation, the current on/off ratio of the device changes by nearly five orders of magnitude, and the maximum current on/off ratio is expected to be achieved 10⁶. The photocurrent measurement reveals the behavior of recombination and space charge confinement, further verifying the bidirectional rectification behavior of heterojunctions, and it also exhibits excellent performance in light response. In the future, Bi₂O₂Se/WSe₂ heterojunction field-effect transistors have great potential to reduce the volume of integrated circuits as a bidirectional controlled switching device.     

磁控溅射制备Ga2O3/ITO深紫外透明导电膜的光电性能

采用磁控溅射方法在石英玻璃基底上制备了Ga2O3/ITO膜,用紫外-可见分光光度计、四探针测试仪对ITO膜和 Ga2O3/ITO膜的光学透过率和面电阻进行了表征,详细研究了ITO层和Ga2O3层的厚度对Ga2O3/ITO双层膜光电性能的影响。研究表明,Ga2O3(50nm) /ITO(23nm)膜在280nm处的深紫外光学透过率高达77.6%,面电阻为323Ω/sq;ITO层控制Ga2O3/ITO膜的面电阻,影响Ga2O3/ITO膜的紫外透过率;Ga2O3层厚度调控Ga2O3/ITO膜的紫外区域的光谱形状。