Optical characteristics and intensity parameters of Sm3+ in GeO2, ternary germanate,and borate glasses

Absorption and fluorescence spectra of Sm3+ were measured in GeO₂, ternary germanate, and borate glasses. From these the intensity parameters were calculated by use of the Judd-Ofelt formula.Visible emission and decay times from the⁴G_5/2 level and its relative quantum efficiencies were measured The quantum efficiencies (QE) of the fluorescence in ternary germanate was higher by a factor of 20 than in GeO₂, The small QE in GeO₂, is explained by cross-relaxation between neighboring Sm³⁺ ions. The later process in hindered by the change in glass structure in the presence of modifier ions. A similar effect is observed in other glasses such as borate, where the addition of modifiers increases the QE of fluorescence.     

溶胶-凝胶法制备掺Sm3+的SiO2玻璃的结构及发光性能

利用溶胶-凝胶技术制备了掺不同量Sm3+和不同退火温度下的SiO2凝胶和玻璃,通过三维荧光光谱、激发光谱、发射光谱的测试,确定了Sm3+在SiO2凝胶玻璃中的最佳激发波长为360 nm,最强发射波长为610 nm,激发光谱的峰位置在360、393、464 nm处,发射光谱的峰位置在578、591、595、610、732nm处,分别归属于4G5/2-6H5/2、4G5/2-6H7/2、4G5/2-6H11/2跃迁,并证明当掺杂量达到1.15%时,Sm3+的发光最强,当Sm3+的掺杂量超过1.15%时,发生浓度猝灭效应.     

铋酸盐铒玻璃在1.54 μm处的荧光特性研究

The bismuth glasses with Er3+ and Er3+/Yb3+ co doped were fabricated by the technique of high temperature melting. The absorption and fluorescence spectra, fluorescence lifetime and FWHM were measured. The explanation of concentration quenching in case of high level Er3＋ doped the bismuth glasses is given. The sensitizing of Yb3＋ to Er3＋ in Er3＋/Yb3＋ co doped bismuth glasses is discussed. The explanation of the influence on absorption and fluorescence spectra, fluorescence lifetime and FWHM in case of the change of Er3+ or Yb3+ in bismuth glasses with Er3+/Yb3+ co doped is given. It is found that the change of Er3+ content has obviously influenced the fluorescence lifetime and FWHM while the change of Yb3+ content has remarkably influenced the absorption and fluorescence intensity. The band at around 1.54 μm in Er3+/Yb3+ co doped bismuth glass reaches 76 nm and the fluorescence lifetime is 0.55 ms.     

Spectroscopic properties of Er3+, Yb3 + and Er3 + /Yb3+ doped metaphosphate glasses

The absorption and emission spectroscopies of Er3+ doped and Er3+/Yb3+ codoped Ca(PO3)2, Sr(PO3)2 and Ba(PO3)2 glasses have been studied. From the Judd-Ofelt intensity parameters, the spontaneous emission probabilities of some relevant transitions and the radiative lifetimes of several excited states of Er3+ have been calculated. The decay curves of the Er3+ emission at 1.5 microm have been measured at different temperatures. The data have been fitted using a stretched exponential function and the obtained experimental lifetimes have been compared with the calculated radiative lifetimes. The difference between the experimental and calculated lifetimes is attributed to the presence of traces of OH groups in the host glasses. The absolute OH content in some glasses has been determined from the infrared spectra. The emission spectra at 1.5 microm of the Er3+ ion in the codoped glasses have been measured at different temperatures. The integrated emission intensities decrease significantly on passing from room temperature to 13 K, suggesting a temperature dependence of the rate of the energy transfer process between Yb3+ and Er3+.     

Ce/Tb/Sm共掺杂CaO-B2O3-SiO2发光玻璃的白光发射及其发光颜色调控

用高温熔融法制备了Ce/Tb/Sm三元共掺杂的CaO-B2O3-SiO2发光玻璃材料,并使用荧光分光光度计和CIE色度坐标对其光谱学和发光特性进行了研究.结果表明:在374nm激发下,在Ce/Tb/Sm三元共掺杂发光玻璃的发射光谱中同时观测到了蓝光、绿光和红橙光的发射带,这些发射带的混合实现了白光的全色发射显示.此外,Ce/Tb/Sm三元共掺杂发光玻璃的发光颜色随着Tb4O7含量的减小从绿光逐渐过渡到白光,显示出发光颜色的可调节性,极大地扩展了其在白光发光二极管中的应用.     

Spectral properties of Er3+/Yb3+ codoped tungsten-tellurite glasses

The spectral properties of Er3+/Yb3+ codoped tungsten-tellurite (WT) glasses have been investigated. The measured absorption spectra are analyzed by Judd-Ofelt theory. The compositional change of intensity parameter omega2 is attributed to the change in the covalency between the Er3+ and oxygen ions, the asymmetry in the local structures around the Er3+ ions can be neglected. The lifetimes of 4I(13/2) level of Er3+ in WT glasses are measured and comparable with other TeO2-based glasses. The stimulated emission cross-section is calculated based on McCumber theory. The fluorescence full width at half maximum (FWHM) and the emission cross-section (sigma(peak)) of the 4I(13/2) --> 4I(15/2) transition of Er3+ in different glass hosts have been compared. The suitability of such WT glasses as host materials for 1.5 microm broadband amplification is discussed.     

Optical studies of Eu3+ doped oxyfluoroborate glass

Rare earth doped oxyfluoroborate glasses have been prepared with different concentration of Eu3+. The UV-Vis/NIR optical absorption, laser induced fluorescence and photoacoustic spectra of Eu3+ in this host have been studied. Different optical parameters such as oscillator strength, Judd-Ofelt intensity parameter, stimulated emission cross-section, transition probability, branching ratio and radiative lifetime, etc. have been calculated. Lifetime of the 5D0 level at various concentrations of Eu3+ have been used to explain the concentration dependent fluorescence quenching. The mechanism of quenching was found to be dipole-dipole. Energy transfer have also been studied from Eu3+ to Pr3+ in sample with 1 mol% (Eu3+) + 1 mol% Pr3+.     

Sm3+掺杂CaO-SiO2-B2O3发光玻璃的制备、表征及性质

用高温固相法合制备了以CaO-SiO₂-B₂O₃为基质，Sm³⁺为激活离子的发光玻璃。对Sm³⁺的淬灭浓度、基质中的硼硅比例、其他稀土离子的敏化作用以及基质组成等因素对玻璃发光特性的影响进行了探讨，并用红外和X-衍射分析对样品的结构进行了表征。结果表明：当Sm^3＋掺杂的物质的量分数为1.2%,激发波长λ ＝ 404 nm时,玻璃体60CaO-20SiO₂-20B₂O₃∶1.2Sm^3＋的发光强度为4 838 A.U.( λ ＝ 606 nm );这种发光玻璃具有将紫外及近紫外光转换为橙红色光的特点。少量的Eu^3＋的掺入，对玻璃体的发光起敏化作用；玻璃体中的组分CaO可被ZnO替代。     

Upconversion and fluorescence spectral studies of Er3+/Yb3+-codoped Bi2Q3-GeO2-Ga2Q3-Na2O glasses

The absorption spectra and upconversion fluorescence spectra of Er3+/Yb3+-codoped natrium-gallium-germanium-bismuth glasses are measured and investigated. The intense green (533 and 549 nm) and red (672 nm) emission bands were simultaneously observed at room temperature. The quadratic dependence of the green and red emission on excitation power indicates that the two-photon absorption processes occur. The influence of Ga2C3 on upconversion intensity is investigated. The intensity of green emissions increases slowly with increasing Ga2O3 content, while the intensity of red emission increases significantly. The possible upconversion mechanisms for these glasses have also been discussed. The maximum phonon energy of the glasses determined based on the infrared (IR) spectral analysis is as low as 740 cm-1. The studies indicate that Bi2O3-GeO2-Ga2O3-Na2O glasses may be potential materials for developing upconversion optical devices.     

稀土离子对钐-铕-噻酚甲酰三氟丙酮-三正辛基膦化氧己烷萃取体系纸上荧光的增敏作用及其应用

在Sm3 + 、Eu3 + 噻酚甲酰三氟丙酮 三正辛基膦化氧己烷萃取体系中Y3 + 、La3 + 、Gd3 + 、Tb3 + 、Dy3 + 、Lu3 + 等离子可增强Sm3 + 、Eu3 + 的纸上荧光 ,其中以Tb3 + 的增敏效应最强 ,灵敏度提高了 6倍。将滤纸适当处理后可使Sm3 + 、Eu3 + 的检出限分别达到 0 .15和 0 .0 0 7ng。本法用于混合稀土氧化物中 0 .xng级的Sm3 + 和0 0 0xng级Eu3 + 的同时测定 ,结果满意     

Optical properties of Ho3+ doped oxyfluoroborate glass

Ho3+ doped oxyfluoroborate glasses have been prepared with different concentration of holmium. The absorption and the fluorescence spectra have been recorded and used to determine various optical parameters such as oscillator strength, Judd-Ofelt intensity parameters, electric dipole line strengths, transition probability, branching ratio, stimulated emission cross section etc. Lifetime of the 5S2 level has been measured and found to decrease with an increase of the rare earth concentration. Non-radiative transition probability and quantum efficiency of the radiative transitions have also been calculated.     

Analysis of energy level structure and excited-state dynamics in a Sm 3+ complex with soft-donor ligands: Sm(Et2Dtc)3(bipy)

Using both laser-excited fluorescence and optical absorption methods, we have determined 57 crystal-field (CF) energy levels of Sm 3+ in crystals of Sm(Et2Dtc)3(bipy). The analysis of the energy levels is based on a model Hamiltonian consisting of both free-ion and CF terms. The CF modeling of the experimental energy levels yielded physically reasonable Hamiltonian parameters with a final rms deviation of 17.3 cm(-1). In comparison with Sm 3+ in other hosts, the CF splitting of Sm 3+ in the lattice of Sm(Et2Dtc)3(bipy) is rather weak. The observed fluorescence decay of the 4G(5/2) manifold is single-exponential, with a lifetime of 24.5 mus, indicating only one site of Sm3+ in the lattice. According to the Judd-Ofelt theory, values of three intensity parameters were obtained (Omega(2,4,6) = 1.57, 2.65, and 3.65, in units of 10(-20) cm(-1)). The calculated branching ratios for transitions from the 4G(5/2) manifold are in agreement with experimental values. The calculated radiative lifetime of the 4G(5/2) manifold is 3.24 ms, and the corresponding fluorescence quantum efficiency is only 0.75%. Efficient multiphonon relaxation processes induced by the localized high-frequency vibrational modes in the bipyridyl group may lead to the extremely low quantum efficiency observed. The thermal line broadening and shifts of the 4G(5/2)(1) --> 6F(1/2) transition were observed and fitted very well by the McCumber-Sturge equations with an assumption of Raman phonon scattering processes as the leading relaxation mechanism. The Debye temperature for this crystal is predicted to be 350 K.     

Temperature dependent luminescence characteristics of Sm3+-doped silicate glass

We report here on the optical characterisation of Sm3+ (5 wt%): SiO2 + Al2O3 + Li2O + Na2O + MgO glass from the measurements of optical absorption spectra (at 300 K), total luminescence spectra (10-300 K) and fluorescence lifetimes (10-300 K) of the prominent emission transitions of the Sm3+ ions. Besides its spectral properties, physical and nonlinearity characterising property parameters have also been computed to understand the optical dispersive power of this glass. By the application of Judd-Ofelt parameters (omega(lambda)) of the measured absorption spectrum, the radiative transition probability factors (A) and stimulated emission cross-section (sigma(p)E) of the observed fluorescent levels have been analysed. Both emission intensity and measured lifetimes of the prominent luminescent transition (4G(5/2) --> 6H(7/2)) concerning Sm3+-glass has been showing a descending trend with the rise in temperature with N2-laser (337.1 nm) as the source of excitation.     

Absorption and emission characteristics of Er3+ ions in alkali chloroborophosphate glasses

Alkali chloroborophosphate glasses containing 1 mol% of Er3+ ions were studied experimentally using the absorption and emission spectroscopy. The energy level scheme for the 4f11 (Er3+) electronic configuration was deduced from the observed band energies of the absorption spectra in terms of a parametrized Hamiltonian using the various free-ion spectroscopic parameters. Oscillator strengths (f) measured from the absorption spectra have been analyzed using the Judd-Ofelt theory to evaluate the three intensity parameters omegalambda (lambda = 2, 4 and 6). Reasonable agreement between the measured and calculated f values has been found. Electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were calculated for all the excited states of Er3+ ions. The non-radiative (WNR) relaxation rates from the excited levels to the next lower levels have been calculated and the relationship between the energy gap and non-radiative relaxation rate has been established. These results were used to predict the possible potential laser transitions in Er-doped alkali chloroborophosphate glasses.     

Spectroscopy and upconversion of Dy3+ doped in sodium zinc phosphate glass

Optical absorption and fluorescence spectra of Dy3+ doped in sodium zinc phosphate glasses have been reported. Judd-Ofelt theory has been applied to analyze the spectra and determine the optical parameters such as transition probabilities, radiative lifetime, stimulated emission cross-section, etc. The fluorescence intensity of Dy3+ corresponding to 4F9/2-->6H13/2 transition increases with increasing concentration of Dy3+ but at higher concentrations, concentration quenching is observed. The radiative lifetime of the 4F9/2 level at 1 mol% concentration of Dy3+ in this host is found to be 541 micros. Emission corresponding to 4F9/2-->6H13/2 transition (570 nm) is observed on excitation with NIR radiation due to upconversion. An attempt is made to explain this observation.     

Spectral power distribution and quantum yields of Sm3+-doped heavy metal tellurite glass under the pumping of blue lighting emitting diode

Quantum yields for multichannel transition emissions have been determined in Sm3+-doped heavy metal tellurite glass under the pumping of blue lighting emitting diode for the first time. To achieve this goal, the necessary fluorescence spectra were measured and calibrated in an integrating sphere, which was connected to a CCD detector with a 400 microm-core optical fiber. The spectral power distribution of the sample under the blue LED pumping was derived from the measured spectra firstly, and then the quantum yields for the visible emissions of Sm3+ were calculated based on the distribution and the total quantum yields in visible region is 7.55%. For accurate measurements, integrating sphere method is proved to be a reliable and reproducible way to characterize luminescence and laser materials.     

Laser spectroscopic studies of Tb3+-doped oxyfluoroborate glass

Tb3+-doped oxyfluoroborate glasses have been prepared for different concentrations of Tb. The absorption, fluorescence and photoacoustic spectra of these have been recorded and studied. It is marked that the fluorescence intensity of different fluorescence transitions decreases with the increase of Tb ion concentration in the glass. This quenching at higher concentration is due to the energy transfer among the excited and nearest neighbor unexcited Tb ions in the glass. The lifetime measurement confirms it, as the lifetime of a particular state was found to decrease with the increase of Tb ion concentration in the glass. The mechanism of the energy transfer process was determined to involve quadrupole quadrupole interaction. We have also studied the energy transfer from Tb3+-->Pr3+ when both the rare earths are doped together in the glass. A decrease in the lifetime of the 5D4 level of Tb3+ with the increase of Pr3+ concentration confirms this.     

Hole Burning and Fluorescence Spectra of Sol-Gel Derived Sm2+-Doped Glasses

Sm2+-doped glasses in the system of Al2O3-SiO2 were prepared by sol-gel processing of metal alkoxides and reacting with H2 gas at 800°C. The hole burning properties of these glasses were investigated. The holes were burned in the 7F0 5D0 line of the Sm2+ ions using a DCM dye laser at 77 K. The hole depth increased with increasing the laser irradiation time, reaching up to 15% of the total intensity within a few hundred seconds. The hole width was 3 cm–1 full width at half maximum. Fluorescence line narrowing spectra of the 5D0 7 F1 transition were analyzed to study the local structure surrounding the Sm2+ ion. It is concluded that the Sm2+ ions are closely coordinated with nine oxygens of the AlO6 group in aluminosilicate glasses and that the addition of Al3+ ions into glass induces an increase in the coordination number of the Sm2+.     

含羧基侧基聚芳醚酮-钐配位聚合物的制备及其荧光性能研究

分别采用自制的3种含羧基侧基的聚芳醚酮(PEK-1、PEK-2和PEK-3)作为高分子配体,1,10-邻菲罗啉(Phen)作为协同配体,钐(Sm3+)作为中心离子,制备了一系列新型的含羧基聚芳醚酮-钐配位聚合物(PEK-Sm3+-Phen).通过红外光谱和紫外-可见吸收光谱分析表明钐离子同时与高分子配体和小分子配体发生了配位,且由X-射线衍射分析证实钐离子通过配位的方式能够均匀地分布于配位聚合物体系中.采用荧光激发和发射光谱对制备的配位聚合物荧光性能进行了研究,结果表明这些配位聚合物在紫外光激发下均能够发射出较强的Sm3+的特征荧光,且因刚性PEK高分子链的引入配位体系的结构更加稳定,并使Sm3+配位环境的对称性降低,从而其荧光强度远高于相应的小分子配合物.同时讨论了不同高分子配体对配位聚合物荧光强度的影响,带有较多烷基取代基的PEK-1使PEK-1-Sm3+-Phen显示出最高的荧光强度.进一步研究了PEK-1-Sm3+-Phen的荧光发射强度与Sm3+含量之间的关系,其荧光强度随着Sm3+含量的增加而逐渐增大,当Sm3+的含量达到15.73wt%时,荧光强度出现最大值.     

Studies of the vibronic interaction between Eu3+ ions and glass-forming units in oxide glasses

Vibronic spectra involving intramolecular vibrations of glass-forming units have been measured for the f–f transitions of Eu³⁺ ions doped into sodium germanate and sodium silicate glasses. It is shown, from the analysis of relative intensities of these spectra, that the interaction of the Eu³⁺ ion with the vibrations of the surrounding forming units of oxide glasses is well described by the electric multipole–multipole interaction.