掺铒铋酸盐玻璃光谱性质的混合形成体效应

测得了Er3+离子在铋酸盐玻璃系列(50～75)Bi2O3-(20～45)B2O3-5Na2O,70Bi2O3-(17～25)B2O3-xZrF4-5Na2O,70Bi2O3-(0～25)B2O3-(0～25)SiO2-5Na2O中的吸收光谱、荧光光谱及4I13/2能级荧光寿命.提出并研究了Er3+离子光谱性质的混合形成体效应,结果表明Er3+离子在铋酸盐玻璃中通过混合形成体效应可以获得较大的有效线宽(△λeff＝62～80nm)、较高的受激发射截面(σe＝0.76～0.84×10-20cm2)、较宽的荧光半高宽(FWHM＝55～80nm)以及较长的荧光寿命(τm＝1.6～4.3ms),说明掺Er3+铋酸盐玻璃是光纤放大器实现宽带和高增益放大较为理想的基质材料.     

Effect of photonic bandgap on upconversion emission in YbPO4:Er inverse opal photonic crystals

We obtained upconversion (UC) light-emitting photonic materials (YbPO(4):Er) with an inverse opal structure by the self-assembly technique in combination with a solgel method. The effect of the photonic stopband on the UC luminescence of the (2)H(11/2), (4)S(3/2)→(4)I(15/2), and (4)F(9/2)→(4)I(15/2) transitions of Er(3+) has been observed in the inverse opals of the Er(3+)-doped YbPO(4). Significant suppression of the UC emission was detected if the photonic bandgap overlapped with the Er(3+) ions emission band, while enhancement of the UC emission occurs if the emission band appears at the edge of the bandgap.     

高声子能量氧化物对掺铒碲酸盐玻璃光谱性质的影响

在研制的Er3+/Ce3+共掺低声子能量碲酸盐玻璃(TeO2-Bi2O3-TiO2)中,分别引入高声子能量WO3、SiO2和B2O3氧化物组分,测试了玻璃样品400~1700 nm范围内的吸收光谱、1.53μm波段荧光谱、Er3+离子荧光寿命和拉曼光谱,结合McCumber理论计算了Er3+离子光谱参数.结果表明:高声子能量氧化物组分的引入,能使声子参与的Er3+/Ce3+离子间能量传递过程变得更为有效,增加了Er3+离子亚稳态能级4I13/2上粒子数积累,从而增强1.53μm波段荧光发射.另外,高声子能量氧化物组分的引入还可以增加荧光半高宽(FWHM)和带宽品质因子(σe×FWHM).研究结果对于获取具有优异光谱特性的掺Er3+光纤放大器(EDFA)的玻璃基质具有实际意义.     

Sequence lasing in a gain-switched Yb3+,Er(3+)-doped silica double-clad fiber laser

Experimental results relating to the gain-switched operation of a double-clad Yb3+,Er(3+)-doped silica fiber laser that is pulse pumped with the output from a flash-lamp-pumped Ti:sapphire laser are presented. For all the configurations of the fiber laser that we studied, the 2F5/2-->2F7/2 laser transition of the Yb3+ ion lased prior to laser emission from the 4I13/2-->4I15/2 transition of the Er3+ ion. To the best of our knowledge, this is the first reported operation of sequence lasing in the Yb3+,Er(3+)-codoped system. This succession of laser pulses deduced from the measurements of this investigation is a consequence of both the short intense pump pulse and the short 900-nm wavelength of the pump that does not overlap with any important excited-state absorption transitions. We believe that the predominant interionic interaction during the course of the pump pulse is the double-energy transfer to the Er3+ ion acting twice from the 2F5/2 energy level of the Yb3+ donor ion. A maximum total output of 1.65 mJ is obtained (1.38 mJ from the 2F5/2-->2F7/2 transition of Yb3+ and 0.27 mJ from the 4I13/2-->4I15/2 transition of Er3+) from a nonoptimized configuration of the fiber laser. The wavelength of the output from the fiber laser was measured to vary approximately linearly with fiber length from 1040 to 1046 nm for the Yb(3+)-based laser and 1535 to 1541 nm for the Er(3+)-based laser.     

Preparation and visible emission of Er-doped 12CaO x 7Al2O3 powder

Er(3+)-doped 12CaO x 7Al2O3 (C12A7:Er3+) powders were prepared using the sol-gel method. X-ray diffraction, micro-Raman spectra and absorption spectra showed that C12A7:Er3+ powder had been obtained. Sharp and intense Er(3+)-related emission from C12A7:Er3+ powder with different Er3+ concentrations in the visible region at room temperature was investigated by analyzing the local structure of Ca atoms in C12A7, and it revealed that cation sites with low symmetry of the host were beneficial to the photoluminescence of Er3+ ions. The emission lines were attributed to two types of Er3+ centers, isolated Er3+ ions and complex centers formed by aggregation of Er3+ ions. The PL intensity might be affected by free oxygen species relative to Er3+ ions formed by charge compensation. The inverse temperature dependent luminescence from the upper level of 2H11/2 state and that from the lower level of 4S3/2 state implied that the thermalization or thermal equilibrium of electrons between the two closely emission states occurred.     

Improved infrared emissions of Er(3+)-Tm3+ co-doped Al2O3 thin films: the role of cross relaxation among rare earth ions

We report the infrared emissions of Er(3+)-Tm3+ co-doped amorphous Al2O3 thin films pumped at 791 nm by a Ti:sapphire laser. The as-deposited films were annealed to improve the photoluminescence performance. Three cross relaxation channels among Er(3+)-Tm3+ and Tm(3+)-Tm3+ ions incorporated in the films were investigated as annealing temperature increases especially from 800 to 850 degrees C. In order to understand the Stark effect and cross relaxations, the photoluminescence spectra were deconvoluted by Gaussian fittings. Our results indicate that the luminescence intensity of 1.62 microm in comparison to 1.5 microm can be enhanced by the cross relaxation process [Er3+ (4I13/2) + Tm3+ (3H6) --> Er3+ (4I15/2) + Tm3+ (3F4)], and the longer-wavelength side of Er3+ emission can be improved by the CR process [Er3+ (4I15/2) + Tm3+ (3H4) --> Er3+ (4I3/2) + Tm3+ (3F4) at expense of the Tm3+ 1.47 microm emission which is also maybe quenched by the CR effect between themselves. These results suggest one possible approach to achieve broadband infrared emissions at the wavelength region of 1.45-1.65 microm from the Er(3+)-Tm3+ co-doped systems.     

Absorption and emission cross sections of Er(3+) in Al(2)O(3) waveguides

Al(2)O(3) slab waveguide films were doped with erbium using ion implantation to a peak concentration of 1.5 at. %. Prism coupling measurements show absorption caused by (4)I (15/2) ?(4)I (13/2) intra-4f transitions in Er(3+) with a maximum at 1.530 mum of 8 dB/cm. The Er(3+) absorption cross section is determined as a function of wavelength. We used the McCumber theory to derive the emission cross section spectrum from the absorption results, which we then compared with the Er(3+) photoluminescence spectrum. The peak absorption and emission cross sections are found to be 6 x 10(-21) cm(-2). The results are used to predict the optical gain performance of an Er-doped Al(2)O(3) optical amplifier that operates around 1.5 mum.     

P2O3-B2O3-Al2O3-SrO-BaO玻璃中Yb3+非辐射能量转移下Er3+离子的增强发射

本文研究了共掺Er3 +/Yb3 +P2 O3 -B2 O3 -Al2 O3 -SrO -BaO玻璃的能量转移过程。实验中制备了高掺杂Yb3 +离子的双掺Er3 +/Yb3 +的磷酸盐玻璃样品。在Er3 +/Yb3 +掺杂比率 >1 :1 8(mol% )时 ,观测到了基于Yb3 +离子至Er3 +离子能量转移下Er3 +( 4 I13 / 2 →4I15 / 2 )的增强发射和Yb3 +( 2 F7/ 2 →2 F5 / 2 )发射的减弱 ,当Yb3 +离子掺杂浓度超过 2 .1× 1 0 2 1ions/cm3 时 (Er3 +/Yb3 +≤ 1 :1 8,mol% ) ,由于Yb3 +离子的自淬灭效应 ,Er3 +离子的发射强度降低。实验中得到了Yb3 +离子的最佳掺杂浓度为1 .74× 1 0 2 1ions/cm3     

The properties of upconversion luminescence on YAIO3:Er(3+) nanophosphors with different Er(3+) concentrations

We report the properties of upconversion luminescence on Yttrium aluminum perovoskite (YAIO3) doped with trivalent erbium at concentrations of 1, 2, 3, 5 and 7 mol%. The samples were synthesized by solvo-thermal reaction method and the XRD patterns conforms that the YAP:Er(3+) nanophosphors have orthorhombic phase. Efficient green and red upconversion (UC) emission of YAP:Er(3+) nanophosphors was measured under the excitation of 975 nm continuous wave diode laser, and its dynamics and pump power dependence were investigated. As concentration of Er(3+) ion increased from 1 to 7 mol%, the red UC emission increased more rapidly. It is attributed to the energy transfer (4I(11/2) --> 4I(15/2):4I(13/2) --> 4F(9/2)) and to the cross relaxation (4S(3/2) --> 4I(9/2):4I(15/2) --> 4I(13/2)) between Er(3+) ions. In this case, the green and red emissions were yielding from quadratic to linear. These conclusions obtained are confirmed by theoretical investigations based on steady-state rate equations.     

Emission properties of hydrothermal Yb(3+), Er(3+) and Yb(3+), Tm(3+)-codoped Lu2O3 nanorods: upconversion, cathodoluminescence and assessment of waveguide behavior

Yb(3+) and Ln(3+) (Ln(3+) = Er(3+) or Tm(3+)) codoped Lu(2)O(3) nanorods with cubic Ia3 symmetry have been prepared by low temperature hydrothermal procedures, and their luminescence properties and waveguide behavior analyzed by means of scanning near-field optical microscopy (SNOM). Room temperature upconversion (UC) under excitation at 980 nm and cathodoluminescence (CL) spectra were studied as a function of the Yb(+) concentration in the prepared nanorods. UC spectra revealed the strong development of Er(3+) (4)F(9/2) → (4)I(15/2) (red) and Tm(3+) (1)G(4) → (3)H(6) (blue) bands, which became the pre-eminent and even unique emissions for corresponding nanorods with the higher Yb(3+) concentration. Favored by the presence of large phonons in current nanorods, UC mechanisms that privilege the population of (4)F(9/2) and (1)G(4) emitting levels through phonon-assisted energy transfer and non-radiative relaxations account for these observed UC luminescence features. CL spectra show much more moderate development of the intensity ratio between the Er(3+) (4)F(9/2) → (4)I(15/2) (red) and (2)H(11/2), (4)S(3/2) → (4)I(15/2) (green) emissions with the increase in the Yb(3+) content, while for Yb(3+), Tm(3+)-codoped Lu(2)O(3) nanorods the dominant CL emission is Tm(3+) (1)D(2) → (3)F(4) (deep-blue). Uniform light emission along Yb(3+), Er(3+)-codoped Lu(2)O(3) rods has been observed by using SNOM photoluminescence images; however, the rods seem to be too thin for propagation of light.     

Hollow waveguides with low intrinsic photoluminescence fabricated with Ta(2)O(5) and SiO(2) films

A type of integrated hollow core waveguide with low intrinsic photoluminescence fabricated with Ta(2)O(5) and SiO(2) films is demonstrated. Hollow core waveguides made with a combination of plasma-enhanced chemical vapor deposition SiO(2) and sputtered Ta(2)O(5) provide a nearly optimal structure for optofluidic biofluorescence measurements with low optical loss, high fabrication yield, and low background photoluminescence. Compared to earlier structures made using Si(3)N(4), the photoluminescence background of Ta(2)O(5) based hollow core waveguides is decreased by a factor of 10 and the signal-to-noise ratio for fluorescent nanobead detection is improved by a factor of 12.     

Up-conversion emissions characteristics of non-aqueous sol-gel derived RE3Al5O12 nanocrystals

The RE3Al5O12 (REAG:Er3Al5O12, Er:Y3Al5O12 and Er:Yb3Al5O12) up-conversion (UC) nanocrystals have been prepared by the non-aqueous sol-gel method. The green and red UC emissions are attributed to the 2H(11/2), 4S(3/2) --> 4I(15/2) and 4F(9/2) --> 4I(15/2) transitions of Er3+, respectively, were obtained for all samples with a 975 nm semiconductor LD excitation. For Er3Al5O12 nanocrystals, the green and red UC emissions have similar intensities. Y and Yb ions have no evident effect on the peak positions, but strongly affected the intensities of the green and red UC emissions of the Er. A much higher intensity of the green relative to red UC emission was observed for Er:Y3Al5O12 nanocrystals, however, the red UC emission became predominant for Er:Yb3Al5O12 nanocrystals. It was suggested that the two-photon process was responsible for the green and red UC emissions mechanism for all the samples.     

纳米SiO2含量对尼龙6/SiO2纳米复合材料蠕变性能的影响

通过原位聚合法制备了尼龙6/SiO2纳米复合材料。利用扫描电镜观测了复合材料的表面形貌,结果表明,纳米SiO2颗粒均匀地分布在尼龙6基体中。利用电子万能试验机对不同纳米SiO2含量的复合材料进行了短期(24 h)蠕变性能的测试,结果表明,随着纳米SiO2含量的增加,复合材料的抗蠕变性能也随着增大;在30 MPa、40 MPa和50 MPa的应力水平下,纳米SiO2含量为5%的纳米复合材料的蠕变应变分别比纯尼龙6降低了38.4%、61.0%和71.9%。     

Sol-gel preparation of near-infrared broadband emitting Er-doped SiO2-Ta2O5 nanocomposite films

This article reports a study on the preparation, densification process, and structural and optical properties of SiO₂-Ta₂O₅ nanocomposite films obtained by the sol-gel process. The films were doped with Er³⁺, and the Si:Ta molar ratio was 90:10. Values of refractive index, thickness and vibrational modes in terms of the number of layers and thermal annealing time are described for the films. The densification process is accompanied by OH group elimination, increase in the refractive index, and changes in film thickness. Full densification of the film is acquired after 90 min of annealing at 900 °C. The onset of crystallization and devitrification, with the growth of Ta₂O₅ nanocrystals occurs with film densification, evidenced by high-resolution transmission electron microscopy. The Er³⁺-doped nanocomposite annealed at 900 °C consists of Ta₂O₅ nanoparticles, with sizes around 2 nm, dispersed in the SiO₂ amorphous phase. The main emission peak of the film is detected at around 1532 nm, which can be assigned to the ⁴I_13/2 → ⁴I_15/2 transition of the Er³⁺ ions present in the nanocomposites. This band has a full width at half medium of 64 nm, and the lifetime measured for the ⁴I_13/2 levels is 5.4 ms, which is broader compared to those of other silicate systems. In conclusion, the films obtained in this work are excellent candidates for use as active planar waveguide.     

The two-photon excitation of SiO(2)-coated Y(2)O(3):Eu(3+) nanoparticles by a near-infrared femtosecond laser

In order to improve the photoluminescence property of Eu(3+)-doped nanoparticles, Y(2)O(3):Eu(3+) nanoparticles were synthesized using the Pechini-type sol-gel method, then coated with SiO(2) shells by using the St?ber method for different coating times. The SiO(2)-coated nanoparticles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, and their photoluminescence spectra were recorded under 800?nm femtosecond laser excitation. The results indicate that a two-photon simultaneous absorption upconversion luminescence is obtained, and their upconversion luminescence intensities are further enhanced after the surfaces of the nanoparticles are coated with different thickness SiO(2) shells. Compared to the upconversion luminescence intensity of non-coated nanoparticles at 611?nm, the upconversion luminescence intensities of SiO(2)-coated Y(2)O(3):Eu(3+) nanoparticles with coating times of 60, 90 and 120?min were enhanced by 3.30, 3.96 and 4.13 times, respectively. This can be attributed to the contributions of the increased amounts of Eu(3+) ions populated at the (5)D(0) level on the surfaces of the nanoparticles because the cooperative ligand fields between the Y(2)O(3) core and non-crystalline SiO(2) shell interfaces activate the 'dormant' Eu(3+) ions near or on the surfaces of the nanoparticles. From a Judd-Ofelt (J-O) theory analysis, the coated shell structures can improve the radiative quantum efficiencies of Eu(3+)-doped nanoparticles. It is therefore concluded that more intense red upconversion luminescence with high radiative quantum efficiencies can enable the SiO(2)-coated Y(2)O(3):Eu(3+) nanoparticles to have the great potential to be used as a fine resolution phosphor.     

Room-temperature 1.643-µm Er(3+):Y(3)Sc(2)Ga(3)O(12) (Er:YSGG) laser

Laser operation at 1.643 μm ((4)I(13/2)-(4)I(15/2)) in Er(3+):Y(3)Sc(2)Ga(3)O(12) (Er:YSGG) at 300 K is reported. An Er:glass laser (1.532 μm) was used in an end-pumping arrangement to obtain laser output from a 1-cm-long 0.7% Er(3% Yb, 1% Cr):YSGG crystal in an external cavity. The Er:YSGG laser exhibited an 18-mJ threshold and a 10% slope efficiency.     

掺铒铋基玻璃的荧光俘获和浓度猝灭效应研究

用高温熔融法制备了系列掺铒铋硼锗酸盐玻璃,测试分析了不同铒离子掺杂浓度下玻璃样品的吸收光谱和荧光光谱.结果显示,掺铒铋硼锗酸盐玻璃中存在着强烈的荧光俘获和浓度猝灭效应.随着铒离子掺杂浓度的增加,1.53 μm波段荧光谱展宽,1 560 nm波长处荧光次峰相对增强.对此用一个等效的四能级模型予以了定性分析.同时,随着铒离子掺杂浓度的增加,4I13/2能级荧光寿命和1.53 μm波段荧光强度呈现出先增加后减小趋势.依据Dexter能量转移理论,计算了该玻璃系统中铒离子发生浓度猝灭的临界距离R0及相互作用参数CEr-Er,并与其它玻璃基质进行了比较.     

Fluorescence of Ta(2)O(5) thin films doped by kilo-electron-volt Er implantation: application to microcavities

Luminescent layers are prepared by the implantation of kilo-electron-volt Er ions into tantalum pentoxide (Ta(2)O(5)) thin films made by ion plating. The implantation fluences range from 3.3 × 10(14) to 2 × 10(15) ions/cm(2), and the energies range from 190 to 380 keV. Refractive index, extinction coefficient, and losses on guided propagation are investigated. We show that these Er-implanted layers present an absorption as low as that of the nonimplanted films. When optically pumped with an Ar(+) laser (λ = 0.488 μm) beam, implanted films show peaked fluorescence spectra centered near 1.53 and 0.532 μm. We show that the fluorescence intensity is correlated with the intensity of the pump beam in the region where Er ions are implanted. Radiation patterns of Er ions located inside a single layer or inside a Ta(2)O(5)/SiO(2) dielectric stack made by ion plating are also investigated. We show that, in any case, spontaneous emission of Er ions can be spatially controlled.     

Enhanced pumping energy transfer between Si nanocrystals and Erbium ions in Si-rich SiOx sputtered using Si/Er2O3 encapsulated SiO substrate

We investigate the enhanced pumping energy transfer for near-infrared photoluminescence in high-density Si nanocrystals (nc-Si) and Erbium ions co-doped SiOx film, which is obtained by RF magnetron assistant sputtering the SiO target with partially encapsulated Si and Er2O3 chips. In contrast to conventional approaches, the use of SiO instead of SiO2 or Si substrate facilitates the formation of nc-Si in the sputtered SiOx, while the Er2O3 replaces the Er pellets to improves the Er3+ concentrations and prevent the precipitation of Er atoms in the nc-Si and Er3+ co-doped SiOx film. Er3+ ion concentration up to 0.325 atomic % is obtained in the SiOx:Er3+ film under a sputtering power of 100 Watts. Correlation between annealing parameters and energy transferring from nc-Si to Er3+ ions is demonstrated, which reveals an optimized annealing condition at 1000 degrees C for 240 min and highest energy transfer efficiency from 760 to 1535 nm by the nc-Si with size and density of 4.5 nm and 10(18) cm(-3) is observed.     

Fabrication and up-conversion luminescence of Er3+:Y2O3 nanoparticles

Y2O3 nanoparticles doped with different concentrations of Er3+ were prepared by the co-precipitation method. X-ray diffraction and transmission electron microscopy results show that Er3+ dissolves completely in the Y2O3 cubic phase. The Er3+:Y2O3 nanoparticles are homogeneous in size and nearly spherical, and the average diameter of the particles after being calcined at 1,000 degrees C for 2 h is in the range of 40-60 nm. When Er3+:Y2O3 nanoparticles are excited under a 980 nm diode laser, there are two main emission bands: green emission centered at 562 nm corresponding to the 4S3/2/2H11/2 --> 4115/2 radiative transitions and red emission centered at 660 nm corresponding to the 4F9/2 --> 4I15/2 radiative transitions. By changing the doping concentration of Er3+ ions, the up-conversion luminescence can be gradually tuned from green to red.