Novel Tm~(3+)-doped transparent fluorozirconate glass-ceramic containing nanocrystalline

A new transparent Tm3+-doped ZrF4-based nanocrystallized glass with the composition of 55ZrF4-20BaF2-18.8YF3-5AlF5-1.2TmF3 (mol%) (ZBYA) has been prepared by a conventional melting quenching technique and the subsequent heat treatment processes. The glass characteristic temperatures, the apparent activation energy, and the Avrami parameter for crystallization are estimated on the basis of different scanning calorimetry (DSC). The sizes of grown nanocrystals in the glass matrix appear to be 30-36.5 nm and it is studied as a function of the nucleation temperature, also the peak intensity of the nanocrystalline is studied as a function of the nucleation temperature from the X-ray diffraction (XRD) measurement. The rnicrohardness measurement shows that the Vickers microhardness (Hv) values of the heat-treated glass samples are larger than that of the based glass about 17.26%-42.04%.     

Enhanced luminescence in transparent glass ceramics containing BaYF5: Ce3+ nanocrystals

Ce³⁺ doped transparent glass ceramics containing BaYF₅ nanocrystals were prepared by controlled heat treatment of 45SiO₂–15Al₂O₃–10Na₂O–24BaF₂–6Y₂O₃–0.5Ce₂O₃ (mol%) glass. X-ray diffraction and transmission electron microscopy data have revealed the formation of BaYF₅ nanocrystals. Both photoluminescence and X-ray excited luminescence spectra have shown a blue-shift of the emission band of Ce³⁺ on ceramization, which is consistent with the Ce³⁺ environment evolving from a glassy oxide to a fluoride phase. The luminescent intensity of Ce³⁺ ions in the transparent glass ceramics is greatly enhanced compared with the precursor glass under ultraviolet and X-ray excitation. This could be attributed to the Ce³⁺ ions present in the BaYF₅ crystalline phase.     

Multi-photon upconversion luminescence of Er~(3+)-doped Y_2O_3 nanocrystals

Visible upconversion emission intensities are investigated in Er3＋-doped Y203 nanocrystals. We also find that the upconversion intensity varies nonlinearly with the excitation power with a threshold of 110 mW, which indicates that the green and red emissions would be photon avalanche upconversion when the excitation power exceeds the threshold.     

Influence of structural evolution on fluorescence properties of transparent glass ceramics containing LaF3 nanocrystals

The structural evolution and the fluorescence properties of Er³⁺-doped oxyfluoride glass ceramics were investigated for samples at different stages of LaF₃ crystallization. TEM observation revealed the homogeneous precipitation of spherical LaF₃ crystals sized in the range of 10-15 nm among the glassy matrix for a sample heated to 690 °C. The crystallization induced the splitting of Er³⁺ emission peaks and the appearance of upconversion in the visible wave-band, implying the incorporation of Er³⁺ into a low-phonon-energy crystalline fluoride environment. In the isothermal experiment at 650 °C, with the increasing of crystal size that resulted from prolonged heating time, the relative intensity of upconversion emission at 660 nm to that at 540 nm decreased significantly, probably due to the reducing of multiphonon relaxation rate between ⁴S_3/2 and ⁴F_9/2, which was believed to be caused by weaker interactions of the Er³⁺ electronic states in nanocrystals with the vibrational excitations of the surrounding glass medium and with the mixed vibrational modes of nanocrystallites and glass for the system with larger particle size. The remarkable difference in spectrum shape of the visible emissions under 378 nm excitation and 980 nm excitation implied that a certain amount of Er³⁺ ions still remained in the glass matrix after crystallization.     

Er~(3+)-doped fluorogallate glass for mid-infrared applications

We report an Er3t-doped fluorogallate glass with good thermal and chemical stability. The low maximum phonon energy and high mid-infrared(IR) transmittance of the glass are confirmed by Raman and IR spectra,respectively. Based on Judd–Ofelt theory, intensity parameters and radiative properties are determined from the absorption and emission spectra. The proposed glass possesses a large fluorescence branching ratio β(21.71%) and a maximum stimulated emission cross-section σemof Er3t:4I11∕2→4I13∕2transition at 2.71 μm(1.04 × 10-20cm2). The results indicate that it can be potentially applied in high-power 2.7 μm fiber lasers.     

Up-conversion luminescence polarization control in Er~(3+)-doped NaYF_4 nanocrystals

We propose a femtosecond laser polarization modulation scheme to control the up-conversion(UC) luminescence in Er~(3+)-doped NaYF_4 nanocrystals dispersed in the silicate glass. We show that the UC luminescence can be suppressed when the laser polarization is changed from linear through elliptical to circular, and the higher repetition rate will yield the lower control efficiency. We theoretically analyze the physical control mechanism of the UC luminescence polarization modulation by considering on- and near-resonant two-photon absorption, energy transfer up-conversion, and excited state absorption, and show that the polarization control mainly comes from the contribution of near-resonant two-photon absorption. Furthermore, we propose a method to improve the polarization control efficiency of UC luminescence in rare-earth ions by applying a two-color femtosecond laser field.     

Dual-wavelength Bi_2Se_3-based passively Q-switching Nd~(3+)-doped glass all-fiber laser

We demonstrate a dual-wavelength passively Q-switched Nd~(3+)-doped glass fiber laser using a few-layer topological insulator Bi_2Se_3 as a saturable absorber(SA) for the first time, to the best of our knowledge. The laser resonator is a simple and compact linear cavity using two fiber end-facet mirrors. The SA is fabricated by Bi_2Se_3/polyvinyl alcohol composite film. By inserting the SA into the laser cavity, a stable Q-switching operation is achieved with the shortest pulse width and maximum pulse repetition rate of 601 ns and 205.2 kHz,respectively. The maximum average output power and maximum pulse energy obtained are about 6.6 mW and 38.8 nJ, respectively.     

Characterization of Er-doped fluoride glass ceramics waveguides containing LaF3 nanocrystals

Highly Er³⁺-doped fluoride glass ceramics planar waveguides containing LaF₃ nanocrystals have been fabricated by physical vapor deposition (PVD). The solubility of Er³⁺ in the segregated nanocrystals can reach 30 mol% which is much larger than the value found in LaF₃-oxide glass ceramics. A quantitative analysis of the photoluminescence of the 1.54 μm emission band of Er³⁺ ions has demonstrated that erbium ions are partitioned in both crystals and vitreous phase. The short lifetime (2.2 ms) measured for erbium incorporated in LaF₃ crystal lattice is a consequence of concentration quenching while the lifetime is close to 10 ms in the glassy phase. The emission bandwidth has been found to be greater than that of the precursor glass (71 nm at the half-height width). The high Er³⁺ concentration and spectral width could make this nanostructured fluoride material suitable for planar amplifier in the C telecommunication band.     

Guiding properties of proton-implanted Nd~(3+)-doped phosphate glass waveguides

We report on the fabrication and properties of an optical waveguide in Nd~(3+)-doped phosphate glass. The planar waveguide was obtained by 550-ke V proton implantation with a dose of 8.0×10~(16) ions/cm~2. The proton–glass interaction was simulated by the stopping and range of ions in matter(SRIM software). The characteristics of the waveguide including the refractive index profile and the near-field intensity distribution were studied by the reflectivity calculation method and the end-face coupling technique. The optical waveguide demonstrated multi-mode behavior at the wavelength of 632.8 nm.The propagation features of the proton-implanted Nd~(3+)-doped phosphate glass waveguide shows its potential to operate as an integrated photonic device.     

Enhancement of up-conversion luminescence properties in Yb~(3+)/Tm~(3+)/Er~(3+) tri-doped transparent oxyfluoride tellurite glass ceramics

<正>Optically transparent Er~(3+)/Tm~(3+)/Yb~(3+) tri-doped oxyfluoride tellurite based nano-crystallized glass ceramics with the batching composition of 73TeO_2-15ZnO-7ZnF_2-3YF3-1.5YbF3-0.3ErF3-0.2TmF_3(mol%) is prepared by a conventional melting quenching and the subsequent heat treatment processes.The sizes of grown nano-crystals in glass matrix appear to be smaller than 100 nm from the scanning electron microscope measurement.Visible up-conversion luminescence of the as melted glass and glass ceramics is investigated.The three-color up-conversion luminescence intensities by 980-nm pumping are increased significantly due to the heat treatment,and the blue intensity increases with a higher magnitude than other wavelengths after heat treatment.     

Novel Tm3+-doped transparent fluorozirconate glass-ceramic containing nanocrystalline

A new transparent Tm3+-doped ZrF4-based nanocrystallized glass with the composition of 55ZrF4-20BaF2-18.8YF3-5AlF5-1.2TmF3 (mol%) (ZBYA) has been prepared by a conventional melting quenching technique and the subsequent heat treatment processes. The glass characteristic temperatures, the apparent activation energy, and the Avrami parameter for crystallization are estimated on the basis of different scanning calorimetry (DSC). The sizes of grown nanocrystals in the glass matrix appear to be 30-36.5 nm and it is studied as a function of the nucleation temperature, also the peak intensity of the nanocrystalline is studied as a function of the nucleation temperature from the X-ray diffraction (XRD) measurement. The microhardness measurement shows that the Vickers microhardness (Hv) values of the heat-treated glass samples are larger than that of the based glass about 17.26%-42.04%.     

Optical bistability of stimulated-emission lines in Sm(3+)-doped glass microspheres

A third-order optical nonlinear effect in a spherical glass resonator doped with Sm(3+) ions has been observed on stimulated emission lines of the (4)G(5/2)-(6)H(7/2) transition, in which the excitation beam of an Ar(+) laser in a 488-nm single line is coupled with the glass resonator through a prism. A spherical form is produced during a free fall of fractional glasses in a longitudinal electric furnace configured vertically. The prism-coupled glass microsphere exhibits sufficient performance to confine photon energy as a resonance of light inside the sphere and offers the prospect of new applications to functional photonic circuits.     

Frequency-conversion properties of Eu doped chlorophosphate glass ceramics containing CaCl2 nanocrystals

Eu³⁺ ion doped chlorophosphate glass ceramics containing nanocrystals were successfully prepared, and their spectroscopic characterizations were done using absorption, excitation and emission spectra. For the crystallized samples, X-ray diffraction (XRD) and transmission electron microscopy (TEM) experiments evidenced the formation of CaCl₂ nanocrystals. The absorption and emission spectra investigations indicate that a considerable amount of Eu³⁺ ions was trapped in CaCl₂ nanocrystals, and therefore an efficient up- and down-frequency conversion was observed. The comparative spectroscopic studies of Eu³⁺ doped samples suggest that the investigated glass ceramics systems are potentially applicable as frequency-conversion photonics devices.     

Spectroscopic study of local thermal effect in transparent glass ceramics containing nanoparticles

Local thermal effect influencing the fluorescence of triply ionized rare earth ions doped in nanocrystals is studied with laser spectroscopy and theory of thermal transportation for transparent oxyfluoride glass ceramics containing nanocrystals. The result shows that the local temperature of the nanocrystals embedded in glass matrices is much higher than the environmental temperature of the sample. It is suggested that the temperature-dependent thermal energy induced by the light absorption must be considered when the theory of thermal transportation is applied to the study of local thermal effect.     

Nd3+掺杂的氧化镧钇透明激光陶瓷的光谱性能研究

采用传统无压烧结工艺制备了Nd3+掺杂的Y2-2xLa2xO3(x=0.08)透明陶瓷并对其光谱性能进行了研究.结果表明:Nd3+:Y1.84La0.16O3透明陶瓷在780-850 nm的波长范围内有较宽的吸收带.当Nd 3+ 掺杂量为1.5at%时,在820 nm和激光二极管抽运的808 nm处的吸收截面分别为σ abs (820 nm)= 1.81×10-20 cm2, σabs (808 nm)=1.54×10-20 cm2.最强的发射峰位于1078 nm处,并具有荧光寿命长、发射带宽宽、量子效率高等特点.加入La2O3后,基质的光谱品质参数 X Nd 由1.6减小到0.46,因此和4F3/2-4I 11/2 跃迁相对应的荧光分支比βJ,11/2 增大为56.82%.Nd 3+:Y1.84La0.16O3 透明陶瓷的这些性质有利于高效率的激光输出和超短锁模激光脉冲的实现.     

Luminescence behavior of Tb ions in transparent glass and glass-ceramics containing CaF2 nanocrystals

Transparent glass-ceramics have been fabricated by heat treatment with 1.0 mol% Tb₂O₃-doped 45SiO₂-20Al₂O₃-10CaO-25CaF₂ aluminosilicate glass. The precipitated crystalline phase in the glass-ceramics is CaF₂ nanocrystals with a size of 15-27 nm and dispersed in the amorphous phase. Both photo- and radioluminescence measurements show that the increase of Tb³⁺ 545 nm line intensity by a factor of 4 and 3.5 is obtained in glass-ceramics with respect to the as-made glass, respectively.     

Tb3+掺杂硅酸盐闪烁玻璃对硬X射线的能量响应

采用高温熔融法制备了Tb3+掺杂硅酸盐闪烁玻璃,并测量了该闪烁玻璃对5～80 keV硬X射线的能量响应.结果表明:硅酸盐闪烁玻璃的光电流对不同光子能量X射线的响应是非线性的,尤其在8和50keV附近,其非线性变化较明显,这种现象与闪烁玻璃吸收X射线后产生大量光电子及其对电子的能量响应有关系.在73.38 keV处,硅酸...     

硼酸镁中Ce^3＋,Gd^3＋对Dy^3＋发光的敏化作用

本文研究了铈、钆、镝激活硼酸镁的激发光谱、发射光谱、发光寿命和能量传递过程。