Comparison of selected optical properties of oxyfluoride glass fibers doped with Er3+ and co-doped with Er3+ Yb3+

The method of manufacturing and spectroscopic evaluation of the Er³⁺ ions doped and Er³⁺–Yb³⁺co-doped SiO₂–Al₂O₃–Na₂CO₃–CaO–PbO–PbF₂ oxyfluoride glass fibers is presented in the paper. Both optically active elements erbium and ytterbium were introduced into the batch in the form of fluorides. The X-ray diffraction (XRD) technique was applied at each stage of fibers manufacturing in order to control an amorphous structure of the preforms and fibers. Optical studies of glass preforms and fibers (reflection/transmission, absorption, emission, and excited state absorption (ESA)) were directed to examine their suitability as fiber amplifiers at 1.55 μm band.     

Enhancement of upconversion intensity in Er3+ doped tellurite glass in presence of Yb3+

TeO₂–PbO glasses doped/codoped with Er³⁺/Er³⁺-Yb³⁺ ions have been fabricated by melting and quenching method. Efficient frequency upconversion emissions spanning from blue to red regions corresponding to the ²H_11/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions, respectively, upon excitation with 976 nm diode laser radiation have been observed. The variations observed in the intensity of whole upconversion emission spectra due to the presence of the Yb³⁺ ions are reported and discussed in detail.     

Effect of concentration of Er3+ ions on ultra-large index of refraction via atomic coherence in Er3+: YAG crystal

A four-level system is proposed to produce large index of refraction accompanied by vanishing absorption in the Er^{3+}-doped yttrium aluminium garnet (YAG) crystal. It is found that the high index of refraction with zero absorption can be provided by adjusting the incoherent pumping, the coherent field, as well as the concentration of Er^{3+} ions in the crystal. Furthermore, the value of the incoherent pump to achieve the high index of refraction with zero absorption is greatly changed with increasing the concentration of Er^{3+} ions in the crystal. This indicates that the effect of concentration on the high index of refraction with zero absorption cannot be neglected.     

Role of incoherent pumping and Er3+ ion concentration on subluminal and superluminal light propagation in Er3+-doped YAG crystal

We study the absorption-dispersion process and group index of weak probe field in a four-level Er3+:YAG crystal.We find that the Er3+ion concentration and incoherent pumping field can influence the absorption-dispersion process and group index of weak probe field.Moreover,our results show that Er3+ion concentration plays a major role in lasing without inversion and absorption with inversion.     

Study of the optical characteristics of TZLB glass activated by Er3+ and Yb3+ ions

The transmission spectra of glass based on tellurium oxide (TeO₂), of the TeO₂-ZnO-Li₂OBi₂O₃ composition (TZLB), which is highly stable to crystallization, have been measured. The concentration dependences of the luminescence (1.53 μm) intensity and kinetics of erbium ions under 975-nm excitation have been investigated. Based on the experimental results, a fundamental possibility of using TZLB glasses activated by Er³⁺ and Yb³⁺ ions for active elements of fiber and integrated optics is shown.     

高Yb~(3+)/Er~(3+)掺杂的磷基有源光纤材料的光谱性质

研究了Yb3+/Er3+共掺60P2O5-15BaO-10Al2O3-5ZnO-10R2O(R=Na,K)以P2O5为主体的磷基有源光纤材料的光谱性质,以及不同Yb3+/Er3+掺杂浓度对光谱性质的影响规律。当Er3+浓度为9.100×1019/cm3、Yb3+的掺杂浓度为5.407×1020/cm3、Yb3+/Er3+浓度比为6∶1时,玻璃样品在1 531 nm处的受激发射截面最大,为6.17×10-21cm2。同时,其荧光寿命为9.73 ms,荧光半高宽为53.16 nm,发射截面与半高宽的乘积为3.28×10-32m3,综合性能最佳。     

Er~(3+)浓度对Er~(3+)/Yb~(3+)共掺氟氧化物玻璃陶瓷上下转换发光的调控(英文)

在980nm激光激发下,Er3+/Yb3+共掺的发光材料既可以在可见光范围产生上转换发光,也可以在近红外波段产生下转换发光,二者存在竞争关系。本文利用熔融淬火法制备了一系列掺杂不同Er3+/Yb3+浓度的氟氧化物玻璃陶瓷,测量了样品在980 nm激光激发下的上转换及下转换发射光谱。研究发现,改变Er3+的掺杂浓度可以调控上下转换的发光强度。在此基础上,提出了上下转换发光的能量传递模型。本文的研究结果有利于该类材料在不同领域中的应用。     

Influence of Ga+ ion irradiation on thermal relaxation of exchange bias field in exchange-coupled CoFe/IrMn bilayers

This paper reports that the CoFe/IrMn bilayers are deposited by magnetron sputtering on the surfaces of thermallyoxidized Si substrates.It investigates the thermal relaxations of both non-irradiated and Ga + ion irradiated CoFe/IrMn bilayers by means of holding the bilayers in a negative saturation field.The results show that exchange bias field decreases with the increase of holding time period for both non-irradiated and Ga + ion irradiated CoFe/IrMn bilayers.Exchange bias field is also found to be smaller upon irradiation at higher ion dose.This reduction of exchange bias field is attributed to the change of energy barrier induced by ion-radiation.     

Optical temperature sensor based on up-conversion fluorescence emission in Yb3+:Er3+ co-doped ceramics glass

Yb3+:Er3+co-doped oxy-fluoride ceramics glass has been prepared.The mechanism of up-conversion emissions about Er3+was discussed,and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated.The results show that the sensitivity of this sample reaches its maximum value,about 0.0047 K 1,when the temperature is 383 K,indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.     

棱镜耦合法测量掺杂波导模折射率中的误差分析

讨论了棱镜耦合法测量离子交换掺Er-Yb平面光波导中传播模式的模折射率实验中的误差与不确定度,模折射率误差由耦合棱镜折射率与底角及同步入射角误差决定，得出了测量模折射率不确定度的传递公式,作为实例．用Ag^＋-Na^＋离子交换技术,在285℃下交换15min．得到了Er-Yb共掺磷酸盐玻璃平面波导，给出了波导模折射率（@632．8nm）及不确定度。     

Spectroscopic properties and mechanism of Tm^3＋/Er^3＋/Yb^3＋ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals

Transparent Tm^3＋/Er^3＋/yb^3＋ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals are prepared. Under excitation of a 980-nm laser diode （LD）, compared with the glass before heat treatment, the Tm^3＋/Er^3＋/yb^3＋ co-doped oxyfluorogermanate glass ceramics can emit intense blue, green and red up-conversion luminescence and Stark- split peaks; X-ray diffraction （XRD） and transmission electron microscope （TEM） results show that BaF2 nanocrystals with an average diameter of 20 nm are precipitated from the glass matrix. Stark splitting of the up-conversion luminescence peaks in the glass ceramics indicates that Tm^3＋, Er^3＋ and （or） Yb^3＋ ions are incorporated into the BaF2 nanocrystals. The up-conversion luminescence intensities of Tm^3＋, Er^3＋ and the splitting degree of luminescence peaks in the glass ceramics increase significantly with the increase of heat treat temperature and heat treat time extension. In addition, the possible energy transfer process between rare earth ions and the up-conversion luminescence mechanism are also proposed.     

Biaxial behaviour of an optical waveguide fabricated by ion implantation in a uniaxial BaTiO3 substrate

Biaxial behaviour has been observed in a waveguide fabricated by the technique of ion-beam implantation (H⁺ ions: 1 MeV at a rather high dose of 6 × 10¹⁶ ions/cm²) in a uniaxial BaTiO₃ single crystal. For the first time to our knowledge this phenomenon has been connected to the elasto-optic properties of the material. The index profile reconstructions both for TE and TM modes are led with two methods and we compare the results. The computation technique to connect the latter with the elasto-optic properties is presented. Then the calculations are successfully compared with the measured values.     

Ag@SiO2纳米核壳结构对铒碲发光玻璃的发光增强机制

本研究首次把预先制备好的Ag@SiO₂纳米核壳结构成功地引进到碲化物发光玻璃70TeO₂-25ZnO-5La₂O₃-0.5Er₂O₃体内,发现(A)Ag(1.6×10^?6mol/L)@SiO₂(40 nm)@Er³⁺(0.5%):铒碲发光玻璃相对于样品(B)Er³⁺(0.5%):铒碲发光玻璃的可见光与红外光的激发光谱强度的最大增强依次为149.0%与161.5%,可见光与红外光的发光光谱强度则依次最大增强了155.2%与151.6%,同时还发现样品(A)相对于样品(B)的寿命显著变长。由于Ag@SiO₂的表面等离子体吸收峰恰好位于546.0 nm,它与铒离子的发光峰546.0 nm完全共振,因此,Ag@SiO₂对铒碲发光玻璃的发光共振增强作用显著。由于银的纳米核壳结构与玻璃的制作具有分步实现的优点,它既能成功控制Ag@SiO₂的尺寸,而且在Ag@SiO₂@Er:铒碲发光玻璃的制作过程中还具有可操作性强的优点,同时价格也更加便宜。在保证银不被氧化的前提下,还可控制稀土离子发光中心与银的表面等离子体之间的距离,因此能够成功地减少背向能量反传递。上述优点促成了Ag@SiO₂纳米核壳结构表面等离子体有效加强了Ag@SiO₂@Er³⁺:铒碲发光玻璃的常规光致发光强度。     

Lu_(2)O_(3)∶Er^(3+)/Yb^(3+)荧光材料的上转换发光及其温度传感特性EI北大核心CSCD

采用CO_(2)激光区熔法制备了Lu_(2)O_(3)∶0.5%Er^(3+)/x%Yb^(3+)(x=1,3,5)上转换荧光材料。X射线衍射结果表明,所制备的Lu_(2)O_(3)∶Er^(3+)/Yb^(3+)荧光材料具有纯Lu_(2)O_(3)晶相。在980 nm激光激发下,样品发出明亮的上转换荧光。光谱测试结果表明,样品上转换荧光强度和荧光中绿光与红光比例随Yb^(3+)离子浓度改变,当Er^(3+)和Yb^(3+)离子浓度分别为0.5%和3%时,样品上转换荧光强度最强。通过荧光强度比(FIR)技术研究了样品Lu_(2)O_(3)∶0.5%Er^(3+)/3%Yb^(3+)在298~873 K温度范围内上转换荧光温度传感特性,在532.8 K时最大绝对灵敏度为0.0060 K^(-1),在298 K时最大相对灵敏度为0.0090 K^(-1)。结果表明,Lu_(2)O_(3)∶Er^(3+)/Yb^(3+)荧光材料非常适合用于宽温度范围荧光温度传感。     

Kinetics of the refractive index change in the core of active fibers, doped with Yb3+ and Er3+ ions, under pulsed optical pumping

The kinetics of refractive index change (RIC) in the core of Yb³⁺/Er³⁺ fibers at a radiation wave-length lying beyond the range of resonant absorption of active ions under pulsed pumping of fiber laser has been analyzed. The measurement of RIC kinetics with a Mach-Zehnder interferometer makes it possible to separate the contributions of the electronic and thermal RIC mechanisms and determine quantitatively the temperature profile inhomogeneity in the fiber. The measured values are compared with the numerical estimates derived from the spectral properties of the active medium in order to check the modern models of RIC in active fibers.     

Comparative study of spectroscopic properties of Er^3＋／Yb^3＋-codoped tellurite glass and fibres under 980nm excitation＊

A tellurite fibre of TeO_{2}－ZnO－La_{2}O_{3}－Li_{2}O glass codoped with 20000 ppm ytterbium and 5000 ppm erbium was fabricated by the suction casting and rod-in-tube technologies. The absorption spectrum of Er^{3+}/Yb^{3+} -codoped bulk glass has been measured. From the Judd－Ofelt intensity parameters, the spontaneous emission probability and radiative lifetime τ_{rad} of Er^{3+}:{}^{4}I_{13/2}→{}^{4}I_{15/2} transition for the bulk glass have been calculated. The emission fluorescence spectra and lifetimes around 1.5μm, and subsequent upconversion fluorescence in the range of 500－700nm were measured in fibres and compared with those in bulk glass. The changes in amplified spontaneous emission with fibre length and pumping power was also measured. It was found that the emission spectrum from erbium in fibres is almost twice as broad as the corresponding spectrum in bulk glass when pumped at 980nm.     

氟化物对Er~(3+)/Yb~(3+)共掺的碲酸盐玻璃上转换和红外发光性能的影响

Er3+/Yb3+共掺的碲酸盐玻璃由于其良好的上转换发光性能而得到广泛的研究。本文将氟化物引入碲酸盐玻璃中,通过熔融法制备了量比为70TeO2-(30-x)ZnO-xZnF2-0.15Er2O3-1.5Yb2O3(x=0,5,10,15,20)的碲酸盐氧氟玻璃样品,并测试其热稳定性、拉曼光谱以及受激发射光谱。实验结果表明,随着氟化物含量的提高,Er3+离子的410,555,670 nm上转换发光和2~3μm波段中红外发光得到增强,并且红光提高强度比绿光和蓝光更明显。在分析了氟离子引入后对上转换与近中红外波段发光的内在影响机制发现:碲酸盐玻璃系统中的氟化物一方面促进能量传递过程中Er3+离子的双光子吸收,促进粒子跃迁至相应的高能级;另一方面,引入氟化物后的碲酸盐玻璃的最大能量声子态密度下降也是降低无辐射跃迁概率、提高上转换和中红外发射强度的重要原因。     

Influence of Ga+ ion irradiation on the magnetisation reversal process and magnetoresistance in CoFe/Cu/CoFe/IrMn spin valves

Ga+ion irradiation is performed on the surfaces of IrMn-based spin valves and the effects of ion irradiation on the magnetisation reversal process and magnetoresistance(MR) are investigated.The results show that the exchange bias field and magnetoresistance ratio of the spin valve decrease with the increase of ion dose.The width of the forward step between the free layer and the pinned layer becomes gradually smaller with the increase of ion dose whilst the recoil step tends to be narrower with ion dose increasing up to 6×10 13 ions/cm 2 and the step disappears afterwards.Two peaks in the R-H curve are found to be asymmetric.     

Spectral properties of Ce3+ doped yttrium lanthanum oxide transparent ceramics

Ce3+-doped yttrium lanthanum oxide (Y0.9La0.1)2O3 transparent ceramics is fabricated with nanopowders and sintered in H2 atmosphere. The spectral properties of Ce:(Y0.9La0.1)2O3 transparent ceramics are investigated. There appear two characteristic absorption peaks of Ce3+ ions at 230 nm and 400 nm, separately. It is found that Ce3+ ions can efficiently produce emission at 384 nm from (Y0.9La0.1)2O3 transparent ceramic host, while the emission is completely quenched in Re2O3 (Re=Y, Lu, La) host materials.     

Effect of B2O3 on Judd—Ofelt parameters of Er^3＋—doped tellurite glasses

We have prepared Er^3 -doped borotellurite glasses using conventional melting and quenching method.The absorption spectrum analysis is performed on the basis of Judd-Ofelt theory.The effects of B2O3 on the spectroscopic parameters such as intersity parameters,line strengths of electric-dipole transitions,and sopontaneous emission probability are discussed.