共查询到20条相似文献,搜索用时 31 毫秒
1.
H. X. Zhang C. H. Kam Y. Zhou X. Q. Han S. Buddhudu Y. L. Lam C. Y. Chan 《Thin solid films》2000,370(1-2):50-53
Tb3+ doped Zn2SiO4 films have been deposited on SiO2 buffered Si wafers by sol–gel method. The structures of these films have been investigated with X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The results revealed that these films were composed of nanometer-size grains with a Willemite structure and had smooth surfaces. Photoluminescence measurements of the films showed a strong emission from 5D4 to 7F5 at 544 nm. The blue emission from 5D3–7Fj was depressed because of cross-relaxation effect. The decay kinetics of the 5D4–7F5 green emission was studied and a best fitting was obtained by a double exponential function. The lifetime of the excited 5D4 state is estimated to be 5.2 ms. 相似文献
2.
Low temperature infrared transmission studies of Nd3+ doped YVO4 were performed, under a magnetic field B c, in the 1800–8000 cm−1 range of the 4I9/2→4I11/2, 4I13/2, and 4I15/2 Nd3+ crystal-field transitions. Good agreement is obtained between the experimental and calculated g-factors. Frequencies of the satellites in the 4I9/2→4F3/2 transitions of the Nd3+ isolated ion confirm the presence of ferromagnetic interactions between pairs of coupled Nd3+ ions that lift the Kramers doublet degeneracies of their ground state and excited multiplets. 相似文献
3.
Rate equations formalism is used to predict the population ratio of the Er3+ 4I13/2 levels involved in the 1.55 μm laser transition in the Yb:Er:CAS laser materials. An effective Yb → Er energy transfer, favourable to the Er3+ 1.55 μm laser emission, is demonstrated in this laser host. Indeed, the Yb → Er transfer and the Er → Yb back transfer rates are calculated to be 6 x 10−16 and 0.45 x 10−16 cm3 s−1, respectively. Attempts of codoping the system with Nd3+, Eu3+ and Ce3+ have been realised in order to increase the population of the Er3+ 4I13/2 laser emitting level. Best results are obtained with Ce3+ ion since in the sample containing 6 x 1020 Ce3+/cm3, the Er3+ 4I11/2 level lifetime is divided by a factor of 3 while the Er3+ 4I13/2 fluorescence lifetime remains unaffected. On the contrary, codoping with Nd3+ or Eu3+ ions simultaneously decreases the Er3+ 4I11/2 and 4I13/2 kinetics parameters. The role of the other parameters such as Yb/Er concentrations ratios is also discussed. 相似文献
4.
Rare earth ion (Nd3+, Er3+ and Tb3+)-doped alumina films were prepared by the sol–gel method using aqueous alumina sol. The effects of dopant concentration and treatment temperature on the optical properties, absorption and emission were examined for the doped films. Alumina films prepared by this method gave a high dopant concentration (0–15 mol% per alumina). Significant concentration quenching did not occur in this concentration range. The emissions from 5D3 and 5D4 of Tb3+-doped film reflected sensitively a matrix environment around Tb3+ ions. Er3+- and Nd3+-doped alumina films resonantly excited by cw Ti–sapphire laser (800 nm) showed upconversion emission at room temperature. The former gave 548 nm (4S3/2→4I15/2) and 640 nm (4F9/2→4I11/2) signals, and the latter 640 nm (4G7/2→4I11/2), which were dependent on alumina. 相似文献
5.
O. Guillot-Noël B. Viana B. Bellamy D. Gourier G. B. Zogo-Mboulou S. Jandl 《Optical Materials》2000,13(4):427-437
Nd3+ : YVO4 is one of the most interesting laser hosts for micro and diode-pumped solid state lasers. We have studied magnetic and optical properties of Nd3+ in three zircon type crystals YMO4 (M=V, As, P). In particular, Nd3+ ions exhibit in the three hosts a multisite character observed in the absorption and emission spectra. However, the emission and its dynamics are strongly dependant on the reabsorption mechanisms. In Nd : YVO4, single crystals containing 7 ± 1 × 1018 Nd3+ ions/cm3, the lifetime is 95 ± 2 μs in good agreement with the calculated radiative lifetime. Electron Paramagnetic Resonance (EPR) measurements are performed to identify the nature of the different substitution sites for Nd3+ ions. Nd3+ ions are found to be inhomogeneously distributed in tetragonal D2d symmetry sites, in isolated ions, “shallow clusters” and pairs. Proportions of the different local environments depend on the total neodymium concentration. For instance, 15% of the Nd3+ ions are gathered in Nd3+–Nd3+ pairs for 7.2 ± 0.2 × 1019 Nd3+ ions/cm3. 相似文献
6.
In the hexaaluminate laser material La0.9Nd0.1MgAl11O19 also known as LMA:Nd the Nd3+ fluorescence can be enhanced by codoping the matrix with rare-earth (REn+) or transition metal (TMm+) ions. A large number of potential donor ions D (D = Mn2+, Dy3+, Tb3+, Eu2+, Eu3+ and Ti3+) are studied in the hexaaluminate host. The D→Nd3+ energy transfer, t he, luminescent efficiency as well as the back-transfer strongly depend on the overlap of the D emission and Nd3+ absorption, the concentration of the two ions and their localization in the crystal host. In this paper the optical properties — absorption and emission — of the D and Nd3+ ions as well as the D→Nd3+ interactions are considered using a Forster-Dexter's approach, to compare the capabilities of the different donors in the Nd3+-doped hexaaluminate host. The CDNd and R0 parameters are estimated in each case, and the results discussed in terms of the localization of the donor ions, their absorption and emission as well as their lifetime properties. 相似文献
7.
The synthesis and photoluminescent (PL) properties of calcium stannate crystals doped with europium grown by mechanically activated in a high energy vibro-mill have been investigated. The characteristics of Ca2SnO4:Eu3+ phosphors were found to depend on the amounts of europium ions. The XRD profiles revealed that the system, (Ca1−xEux)2SnO4, could form stable solid solutions in the composition range of x = 0–7% after being calcined at 1200 °C. The calcined powders emit bright red luminescence centered at 618 nm due to 5D0 → 7F2 electric dipole transition. Both XRD data and the emission ratio of (5D0 → 7F2)/(5D0 → 7F1) reveal that the site symmetry of Eu3+ ions decreases with increasing doping concentration. The maximum PL intensity has been obtained for 7 mol% concentration of Eu3+ in Ca2SnO4. 相似文献
8.
Dhiraj K. Sardar Santiago Vizcarra Mohammad A. Islam Toomas H. Allik Edward J. Sharp Albert A. Pinto 《Optical Materials》1994,3(4):257-263
Spectroscopic and EPR investigations of Nd3+-doped CaZn2Y2Ge3O12 (CAZGAR) have been performed. The absorption, fluorescence, excitation spectra and fluorescence lifetime have been measured at room temperature. The Judd-Ofelt theory has been applied to the measured optical absorption intensities to predict the radiative decay rates, branching ratios, and peak stimulated emission cross section from the metastable 4F3/2 state to the 4I9/2 manifold. The fluorescence lifetime of the 4F3/2 level of Nd3+ at low concentration in this host was measured to be 285 ± 10 μs, which is longer than that for Nd3+: YAG. Color centers located at zinc octahedral sites have been produced in these crystals by ultraviolet irradiation and have been detected by EPR techniques. The effects of the color centers on the potential laser characteristics of this materials are discussed. 相似文献
9.
Lu2O3是具有高热导率而成为极具潜力的高功率激光介质材料。实验以商用氧化物粉体为原料, LiF为烧结助剂, 采用放电等离子烧结法制备了不同Nd3+掺杂浓度(CNd=0, 1at%, 3at%和5at%) Lu2O3透明陶瓷, 并研究了Nd3+掺杂浓度对Lu2O3陶瓷的物相、烧结性能、微观结构及光学性能的影响。结果表明:在高Nd3+浓度(5at%)掺杂后烧结样品仍为纯Lu2O3相;Nd3+掺杂对Lu2O3陶瓷烧结性能及微观形貌的影响有限;所有样品最终均表现出高致密性(99.5%以上)和优异的透光性能, 其中3at% Nd3+:Lu2O3的透过率最高, 在1064和2000 nm处的透过率分别为82.7和83.2%。Nd3+:Lu2O3透明陶瓷的最强发射峰位于1076和1080 nm;且随着Nd3+掺杂浓度的增加, 荧光强度降低, 寿命变短, 发生浓度淬灭。 相似文献
10.
To obtain efficient upconversion laser glass, the optical properties of Tm3+ and Ho3+ were investigated in various glasses. Fluoride glass was selected as base glass for upconversion. The efficient upconversion fluorescences corresponding to the 1G4→3H6 and 3H4→3H6 transitions of Tm3+ and the 5S2→5I8 transition of Ho3+ were observed in Yb3+-Tm3+ and Yb3+-Ho3+ doped aluminozircofluoride glasses excited at 980 nm. The very stronge blue and green emission light can be observed visually. The upconversion processes observed were two-photon processes for 3F4→3H6, 5S2→5I8 transitions and three-photon processes for the 1G4→3H6 transition and can be described by a rate equation model. The energy transfer and energy back-transfer were analyzed in Yb3+-Tm3+ and Yb3+-Ho3+ systems. The relationship between emission intensity, pumping intensity and dopant concentrations is described using a rate equation model and shows good agreement with experiments. The dynamics of excited state (
) is also analyzed with the diffusion-limited model based on Yokota-Tanimoto theory. 相似文献
11.
Fugui Yang Chaoyang Tu Hongyan Wang Yanping Wei Zhenyu You Guohua Jia Jianfu Li Zhaojie Zhu Xiuai Lu Yan Wang 《Optical Materials》2007,29(12):1861-1865
Single-crystal ZnWO4:Dy3+ was grown by Czochralski technique. The XRD, absorption spectra as well as fluorescence spectrum are investigated and the Judd–Ofelt intensity parameters Ω2, Ω4, Ω6 are obtained to be 7.76 × 10−20 cm2, 0.57 × 10−20 cm2, 0.31 × 10−20 cm2, respectively. Calculated radiative transition rate, branching ratios and radiative lifetime for different transition levels of ZnWO4:Dy3+ crystals are presented. Fluorescence lifetime of 4F9/2 level is 158 μs and quantum efficiency is 66%.The most intense fluorescence line at 575 nm correlative with transition 4F9/2 → 6H13/2 is potentially for application of yellow lasers. 相似文献
12.
We report measurements of the energy transfer between Er3+ and Ce3+ in Y2O3. The transition between the Er3+ 4I11/2 and 4I13/2 excited states can be stimulated by energy transfer to Ce3+, augmenting the population in the 4I13/2 state at the expense of that in the 4I11/2 state. Experiments were performed on Y2O3 planar waveguides doped with 0.2 at.% erbium and 0–0.42 at.% cerium by ion implantation. From measurements of Er3+ decay rates as a function of cerium concentration we derive an energy transfer rate constant of 1.3×10−18 cm3/s. The efficiency of the energy transfer amounts to 0.47 at 0.42 at.% cerium. The energy transfer rate constant measured in Y2O3 is two times smaller for Er3+→Ce3+ than that for Er3+→Eu3+ in the same material. 相似文献
13.
Here, we bring out an infrared transmitting new optical glass based on TeO2 added with AlF3 and LiF, containing dual rare earth ions (Eu3+,Nd3+) as the dopants with a purpose to examine their luminescence and also the decay times pertaining to a prominent transition of Eu3+ (5D0 → 7F2 at 615 nm) as a function of temperature both in the presence and absence of Nd3+ ions. The energy transfer rates (Wtr), critical distances (R0) and transfer efficiencies (ηtr) have been evaluated based on the measured lifetime data of this glass. 相似文献
14.
R. Burlot R. Moncorgé H. Manaa G. Boulon Y. Guyot J. Garcia Solé D. Cochet-Muchy 《Optical Materials》1996,6(4):313-330
The polarized absorption and luminescence properties of Nd3+ doped isostructural LiNbO3, MgO:LiNbO3 and LiTaO3 nonlinear bulk single crystals are reported. Pump-probe experiments associated with the Judd-Ofelt approach are used to estimate two types of room temperature cross sections: polarized emission cross sections of the dominant 4F3/2 → 4I1//2 transition near 1085 and 1093 nm and polarized excited-state absorption cross sections in the same spectral domain and in the green spectral range corresponding to self frequency doubling. Self frequency-doubling results are also given in Nd:LiNbO3 and Nd:MgO:LiNbO3 versus sample temperature. 相似文献
15.
Laser excited site-selective luminescence of Nd3+ ion in the Ca3(Nb,Ga)2Ga3O12 garnet crystal has been investigated for the
and
transitions. Six main non-equivalent crystal field sites were detected in the garnet. The crystal splitting scheme of the
and
manifolds was obtained for each Nd3+ site. Energy transfer between Nd3+ sites was observed by using time resolved spectroscopy. 相似文献
16.
Optical absorption and photoluminescence of Ca3(VO4)2 single crystal grown by a floating-zone technique and containing Nd3+ ions were investigated. High absorption coefficients and broadening of most absorption bands are present at 300 K, while substructures in some of the same bands can be evidenced at 12 K. Most features of measured spectra are characteristic of random occupation of more than a single Ca2+ site by the Nd3+ ion and of distortions provoked by different charge compensation mechanisms involving oxygen vacancies promotion in the crystal lattice. Nd3+ optical properties were studied by using the Judd-Ofelt theory to calculate the spectral parameters relevant for laser applications. 相似文献
17.
Kwang-Bok Kim Kyung-Wan Koo Tong-Yul Cho Hui-Gon Chun 《Materials Chemistry and Physics》2003,80(3):682-689
The blue phosphor of BaMgAl10O17:Eu2+ (BAM) powders were prepared by solid-state reaction. The thermal degradation of BAM phosphor significantly reduces the intensity of the blue emission. BAM is reduced by an amount of 50% after heating at around 800 °C for 1 h. Photoluminescence (PL) excitation and emission spectra showed that the blue emission of 450 nm peak decreased with increasing annealing temperature. The 5D0→7F1 and 5D0→7F2 transition of Eu3+ were observed at 590 and 615 nm emission lines over 1100 °C. Electron paramagnetic resonance (EPR) spectrum also detected two signals of Eu2+, corresponding to g=3.7156(9) for 88 mT, and g=2.9507(9) for 133 mT. X-ray absorption near edge structure (XANES) spectrum decreased the intensity of Eu2+ for 6977 eV with increasing annealing temperature, while high-energy peak of Eu3+ for 6984 eV was increased. The combined use of X-ray and neutron data by the Rietveld refinement appears to support that the secondary phase of EuMgAl11O19 magnetoplumbite structure in BAM may be formed by heat treatment. 相似文献
18.
The luminescent quantum efficiency of Cr3+ ions in single fluoride crystal Cs2NaAlF6 was determined by using the simultaneous multiple-wavelength photoacoustic and luminescent experiments method, based on the generation of photoacoustic and luminescence signals after pulsed laser excitation. The luminescent quantum yield for the most important transition between the 4T2→4A2 vibronic levels was found to be 68±3%. This value agrees with that obtained from the ratio of the lifetimes of the corresponding transition at different temperatures. 相似文献
19.
Hongyan Wang Guohua Jia Yan Wang Zhenyu You Jianfu Li Zhaojie Zhu Fugui Yang Yanping Wei Chaoyang Tu 《Optical Materials》2007,29(12):1635-1639
Novel pure and cobalt-doped magnesium borate crystals (Mg3B2O6) have been grown successfully by the Czochralski technique for the first time. Crystal growth, X-ray powder diffraction (XRD) analysis, absorption spectrum, fluorescence spectrum as well as fluorescence decay curve of Co2+:Mg3B2O6 (MBO) were described. From the absorption peaks for the octahedral Co2+ ions, the crystal-field parameter Dq and the Racah parameter B were estimated to be 943.3 cm−1 and 821.6 cm−1, respectively. The fluorescence lifetime of the transition 4T1(4P) → 4T2 centered at 717 nm was measured to be 9.68 ms. 相似文献
20.
Wang Baoshan Tan Huiming Peng Jiying Miao Jieguang Gao Lanlan 《Optical Materials》2007,29(12):1817-1820
Low threshold, high efficient Raman laser output has been realized from a compact, diode end-pumped, self-stimulating Nd3+:GdVO4 Raman laser. Maximum Raman output power of 100 mW was achieved at a pulse repetition frequency (PRF) of 10 kHz with 1.8 W pump power. The optical efficiency is 5.6% from diode to Raman laser and the slope efficiency is 8%. The lowest threshold for the SRS process is only 400 mW at a PRF of 5 kHz. By generating second harmonics using a LBO crystal, 3 mW 588 nm yellow laser was also produced. A strong blue emission was observed in the Nd3+:GdVO4 crystal when the Raman laser output, we contribute this for the upconversion of the Nd3+ in the crystal. 相似文献