Dai Shixun

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).

Investigation on Nonradiative Decay of the Er3+ 4I13/2→4I15/2 Transition in Different Tellurite Glass Matrix

Three kinds of Er3+-doped tellurite glasses with different hydroxyl groups are prepared by the conventional melt-quenching method. Infrared spectra are measured to estimate the exact content of OH? groups in samples. The maximum phonon energy in glasses are obtained by measuring the Raman scattering spectra. The strength parameters ?t (t = 2,4,6) for all the samples are calculated and compared. The nonradiative decay rate of the Er3+ 4I13/2?4I15/2 transition are calculated for the glass samples with different phonon energy and OH? group contents. Finally, the effect of OH? groups on fluorescence decay rate of Er3+ is analysed, the constant KOH?Er of TWN, TZPL and TZL glasses are calculated to be 9.2?10?19?cm4s?1, 5.9?10?19?cm4s?1, and 3.5?10?19?cm4s?1, respectively.

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.

Mid-infrared emission properties of Dy3+ -doped Ge-Ga-S-Csl glasses

A serial of chalcogenide glasses based on Ge-Ga-S-Csl system doped with the different Ho3+ ions were synthesized by melt-quenching technique. The properties of glasses including refractive indexes, absorption spectra, mid-infrared emission spectra and lifetimes of I-5(6) level of Ho3+ ions were measured. The Judd-Ofelt intensity parameters Omega(i)(i=2,4,6), oscillator strength f(cal), spontaneous transition probabilities A(rad) for Ho3+ ion were calculated by Judd-Ofelt theory. Multiphonon relaxation rates of the Ho3+ : I-5(5)-> I-5(6) and I-5(6)-> I-5(7) in Ge-Ga-S-Csl glasses were evaluated. Effect of Ho3+ ion concentration on the fluorescence spectra was investigated. The results indicate that the fluorescence under 900 nm excitation with peak wavelength at 2. 81 mu m and 3. 86 mu m are due to the Ho3+ : I-5(6)-> I-5(6) and I-5(6)-> I-5(7) transition, respectively. The intensity of the mid-infrared fluorescence are enhanced with the Ho3+ ion concentration increasing from 0. 5wt% to 1. 0wt%. Multiphonon relaxation rates are 29s(-1) and 34s(-1) for the Ho3+ : I-5(5)-> I-5(6) and I-5(6)-> I-5(7) transition, respectively.采用熔融冷却法制备了系列不同Ho 3+ 离子掺杂浓度的Ge-Ga-S-CsI玻璃样品，测试了样品的折射率、吸收光谱以及中红外荧光光谱和Ho 3+ 离子5I6能级荧光寿命.应用Judd-Ofelt理论计算了Ho 3+ 离子在该基质玻璃中强度参数 Ω i （ i =2,4,6）、能级跃迁振子强度fcal、自发跃迁几率Arad等光谱参数.计算了Ho 3+ ∶ 5 I 5 → 5 I 6 (3.86μm)和 5 I 6 → 5 I 7 (2.81μm)跃迁的多声子驰豫速率.讨论了中红外荧光特性与Ho 3+ 离子掺杂浓度之间的关系.结果表明，在900nm 激光泵浦下观察到了2.81和3.86μm两处中红外荧光，分别对应于Ho 3+ ∶ 5 I 6 → 5 I 7 和 5 I 5 → 5 I 6 跃迁，当Ho 3+ 离子掺杂浓度从0.5wt%增加到1.0wt%时，两处中红外荧光强度都随相应增加，计算的Ho 3+ ∶ 5 I 5 → 5 I 6 和 5 I 6 → 5 I 7 跃迁多声子驰豫速率分别为29s -1 和34s -1 .

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.