Nie Qiuhua

Influence of B2O3 on Spectroscopic Properties of Er3+/Yb3+ Co-Doped Tungsten-Tellurite Glasses

Abstract A series of novel Er 3+ /Yb 3+ co-doped (85 – x)TeO 2 -15WO 3 - xB 2 O 3 (TWB; x = 2%, 5%, 8% (mole fraction)) glasses were prepared. Influence of B 2 O 3 on the spectroscopic properties of Er 3+ /Yb 3+ co-doped tungsten-tellurite glasses were investigated. It is found that the intensity of 1.5 μm fluorescence, lifetime of the 4 I 13/2 level and upconversion fluorescence all decrease with the increase of B 2 O 3 content. The product of full width at half maximum (FWHM) and stimulated emission cross-section (σ) of Er 3+ : 4 I 13/2 → 4 I 15/2 transition has an optimum when B 2 O 3 is 5% (mole fraction). The emission spectra of Er 3+ : 4 I 13/2 → 4 I 15/2 transition was analyzed using peak-fit routine, and an equivalent four-level system was proposed to estimate the stark splitting for the 4 I 15/2 and 4 I 13/2 levels of Er 3+ ions in TWB glasses at room temperature.

Linear and nonlinear optical properties of Sb-doped GeSe2 thin films*

Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb–Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10−18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10−10 m/W. These excellent properties indicate that Sb-doped Ge–Se films have a good prospect in the applications of nonlinear optical devices.

Improved Fluorescence from Tm3+/Er3+/Ce3+ Triply Doped Bismuth-Silicate Glasses for S+C-bands Amplifiers

Fluorescence of Tm3+/Er3+ codoped bismuth-silica (BS) glasses and the sensitization of Ce3+ are investigated. It shows that Ce3+ codoping with Tm3+/Er3+ in BS glasses results in a quenching of Tm3+ ion emission from 3F4 to the 3H6 level. Consequently, the 1.47 μm emission occurs after the population inversion between the 3H4 and 3F4 levels. Furthermore, the codoped glasses show the broad emission spectra over the whole S and C bands with full-width at half-maximum (FWHM) up to about 119 nm, as it combines 1.55 μm emission band of Er3+ with 1.47 μm emission band of Tm3+ under 800 nm excitation.

High Efficiency Infrared-to-Visible Upconversion Emission in Er3+,Yb3+, and Ho3+ Codoped Tellurite Glasses

A novel method of codoping the Er3+, Yb3+, and Ho3+ ions in tellurite glasses is demonstrated to obtain a high efficiency of infrared-to-visible upconversion. Three intense emission bands observed in Er3+, Yb3+, and Ho3+ codoped tellurite glasses centred at 525, 547, and 657 nm correspond to Er3+: 2H11/2→4I15/2, Er3+: 4S3/2→4I15/2+Ho3+: 5S2(5F4)→5I8, and Er3+: 4S3/2→4I15/2+Ho3+: 5F5→5I8 transitions, respectively. No visible upconversion quenching phenomenon is observed when three rare-earth ions are codoped together in tellurite glasses. In contrast, the upconversion intensity of red and green emissions in Er3+, Yb3+, and Ho3+ codoped glasses is enhanced largely when compared with Er3+/Yb3+-codoped glasses. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms are evaluated. The three emissions are based on two-photon absorption processes.

Phase transformation in Mg—Sb3Te thin films

Mg-doped Sb3Te films are proposed to improve the performance of phase-change memory (PCM). We prepare Mg-doped Sb3Te films and investigate their crystallization behaviors, structural, optical and electrical properties. We find that Mg-doping can increase the crystallization temperature, enhance the activation energy, and improve the 10-year data retention of Sb3Te. Especially Mg25.19(Sb3Te)74.81 shows higher Tc (~ 190 °C) and larger Ea (~ 3.49 eV), which results in a better data retention maintaining for 10 yr at ~ 112 °C. Moreover Ra/Rc value is also improved. These excellent properties make Mg—Sb—Te material a promising candidate for the phase-change memory (PCM).

Thermal Stability and Spectroscopic Properties of New Er3+/Yb3+-Codoped Tellurite Glasses

A series of new Er3+/Yb3+-codoped 70 TeO2–5 Li2O–(25-x)B2O3–xGeO2 (TLBG, x = 0, 5, 10, 15, 20 mol%) glasses are prepared. The thermal stability and spectroscopic properties of TLBG glasses are studied. It is found that these glasses have the better thermal stability ((Tx−Tg)>150 degrees C) compared with 75 TeO2–20 ZnO–5Na2O (TZN) glass. The fluorescence full width at half maximum (FWHM) is about 77 nm, while the emission intensity and the quantum efficiency of the 4I13/2 level of Er3+ increase with the increasing GeO2 content. The maximum quantum efficiency and stimulated emission cross-section of Er3+ calculated from the McCumber theory are 93.82% and 9.0×10−21 cm2, respectively. The products of FWHM and σepeak of Er3+ in TLBG glasses are larger than those in other reported glasses. The obtained data indicate that this kind of TLBG glasses is a promising candidate host material for Er3+-doped broadband amplifiers.

Local Structure of Niobate-Phosphate Glass Using Eu3+ Ion Fluorescence

The niobate phosphate glasses containing Eu3+ ions were fabricated by the melting method. The fluorescence characteristics of the glass at temperatures from 77 K to 700 K were investigated under the excitation of 488 nm light. The results show that the fluorescence intensity of Eu3+ ions first increases and then decreases as temperature increases. The temperature-dependent parameters of the crystal fields and the local structure surrounding Eu3+ ions were investigated and discussed from the situation of splitting energy level of 5D0-7F1. The results indicate that the distance of europium and oxygen become shorter with increasing temperature and the coordination number of Eu3+ ion is near 8, which does not change with temperature.

Tm 3+ /Ho 3+ 共掺硫卤玻璃的2.00 μm荧光特性研究

通过真空熔融淬冷法制备了不同浓度Tm 3+ /Ho 3+ 离子共掺的70GeS 2 -20In 2 S 3 -10CsI玻璃样品, 分析了样品的热稳定性及拉曼光谱, 测试了样品的吸收光谱以及808 nm激光泵浦下Ho 3+ : 5 I 7 → 5 I 8 辐射跃迁对应的2.00 μm荧光光谱特性. 结果表明: Tm 3+ 离子掺杂浓度为0.25mol%时, 随着Ho 3+ 离子掺杂浓度从0.05mol%增加到0.125mol%, Tm 3+ 离子在1.86 μm的发光强度逐渐减弱, Ho 3+ 离子2.00 μm荧光明显增强, 表明Tm 3+ /Ho 3+ 离子之间存在有效的能量转移.通过真空熔融淬冷法制备了不同浓度Tm 3+ /Ho 3+ 离子共掺的70GeS 2 -20In 2 S 3 -10CsI玻璃样品, 分析了样品的热稳定性及拉曼光谱, 测试了样品的吸收光谱以及808 nm激光泵浦下Ho 3+ : 5 I 7 → 5 I 8 辐射跃迁对应的2.00 μm荧光光谱特性. 结果表明: Tm 3+ 离子掺杂浓度为0.25mol%时, 随着Ho 3+ 离子掺杂浓度从0.05mol%增加到0.125mol%, Tm 3+ 离子在1.86 μm的发光强度逐渐减弱, Ho 3+ 离子2.00 μm荧光明显增强, 表明Tm 3+ /Ho 3+ 离子之间存在有效的能量转移.

Concentration Quenching in Erbium Doped Bismuth Silicate Glasses

Er2O3-doped bismuth silicate glasses are prepared by the conventional melt-quenching method, and the Er3+:4I13/2 →4I15/2 fluorescence properties are studied for different Er3+ concentrations. Infrared spectra are measured to estimate the exact content of OH- groups in the samples. Based on the electric dipole–dipole interaction theory, the interaction parameter CEr,Er for the migration rate of Er3+:4I13/2→4I13/2 in proposed glasses is calculated.

Mechanisms and Concentration Dependence of Upconversion Fluorescence in Er3+ and Tm3+ Codoped Tellurite Glasses

We investigate the upconversion luminescence of Er3+ and Tm3+ codoped tellurite glasses under both the 975 and 800 nm excitations. By Tm3+ codoping, the Er3+ green emission corresponding to the (4S3/2, 2H11/2)→ 4I15/2 transitions was quenched, while the red emission corresponding to the 4F9/2→ 4I15/2 transition was selectively sensitized. The red emission has a maximum in the range where the ratio of Er3+- to Tm3+-content is about two and its fluorescence intensity becomes 1.5 and 5 times larger at the maximum than those in the absence of Tm3+ for 975 and 800 nm excitations, respectively. The results were explained considering the influence of energy transfers between these two active ions.