Spectroscopic study of thulium-activated double sodium yttrium fluoride Na<Subscript>0.4</Subscript>Y<Subscript>0.6</Subscript>F<Subscript>2.2</Subscript>:Tm<Superscript>3+</Superscript> crystals: I. Intensity of spectra and luminescence kinetics

Na_0.4Y_0.6F_2.2:Tm³⁺ crystals with a thulium content from 1 to 100 at % have been grown by the Stockbarger-Bridgman method. The optical spectra of Na_0.4Y_0.6F_2.2:Tm³⁺ crystals were investigated in detail at room and low (10 K) temperatures, and the luminescence kinetics was analyzed using different excitation methods. The structure of the Stark splitting of thulium levels as “quasi-centers,” characterized by inhomogeneous broadening of the Stark components, is determined from analysis of the absorption spectrum at 10 K. The oscillator strengths of the transitions from the ground state to excited multiplets are determined from the absorption cross-section spectra at 300 K for ten transitions in the range 5000–38 500 cm^?1 and seven transitions in the range 5000–28 500 cm^?1. The transition intensity parameters Ω _t , obtained by the Judd-Ofelt method from the spectra due to the transitions to ten and seven excited levels, were found to be, respectively, (i) Ω₂ = 1.89 × 10^?20, Ω₄ = 2.16 × 10^?20, and Ω₆ = 1.40 × 10^?20 cm² and (ii) Ω₂ = 2.04 × 10^?20, Ω₄ = 2.01 × 10^?20, and Ω₆ = 1.44 × 10^?20 cm². These values of the intensity parameters were used to calculate the radiative transition probabilities and branching ratios and to estimate the multiphonon nonradiative transition probabilities for NYF:Tm. The luminescence decay kinetics from thulium radiative levels upon their selective excitation by nanosecond laser pulses has been studied and the lifetimes of thulium radiative levels in NYF crystals have been found.     

Spectroscopic study of erbium-activated crystals of double calcium yttrium fluoride Ca<Subscript>0.89</Subscript>Y<Subscript>0.11</Subscript>F<Subscript>2.11</Subscript>:Er<Superscript>3+</Superscript>: I. Intensity of spectra and luminescence kinetics

Ca_0.89Y_0.11F_2.11:Er³⁺ (CYF:Er) crystals with an erbium content of 1–15 at % have been grown. The optical spectra and luminescence kinetics of CYF:Er crystals have been investigated at low (～5 K) and room temperatures. Based on an analysis of the absorption spectra at low temperature, the structure of Stark splitting of erbium levels in CYF:Er crystals is determined. Room-temperature absorption spectra are used to calculate the spectra of absorption cross sections and oscillator strengths of transitions from the erbium ground state to excited multiplets. It is shown that the absorption spectrum of CYF:Er crystals contains broad bands in the ranges of 790–815 and 965–980 nm, which correspond to the range of emission of laser diodes. For the band peaking near 967 nm, the peak absorption cross section is σ _abs ^max = 2.7 × 10^?21 cm². The intensity parameters are determined by the Judd-Ofelt method to be Ω₂ = 1.39 × 10^?20, Ω₄ = 1.34 × 10^?20, and Ω₆ = 2.24 × 10^?20 cm². The radiative transition probabilities, radiative lifetimes, and branching ratios are calculated with these values. The luminescence decay kinetics from excited erbium levels upon selective excitation is investigated and the experimental lifetimes of the 4F _9/2, ⁴ S _3/2, and ⁴ G _11/2 radiative erbium levels are determined. The dependences of multiphonon relaxation rates on the energy gap in CYF:Er crystals are obtained. The rates of nonradiative multiphonon relaxation from radiative erbium levels are determined.     

Spectroscopic study of double sodium-yttrium fluoride crystals doped with erbium Na<Subscript>0.4</Subscript>Y<Subscript>0.6</Subscript>F<Subscript>2.2</Subscript>:Er<Superscript>3+</Superscript>: I. Intensities of luminescence spectra and kinetics of luminescence

Na_0.4Y_0.6F_2.2:Er³⁺ (NYF:Er) crystals with an erbium concentration as high as 100 at. % (Na_0.4Er_0.6F_2.2) were grown by the Bridgman-Stockbarger method. The optical spectra were investigated at low (6 K) and room temperatures. It is shown that the absorption spectrum of NYF:Er crystals contains wide bands (790–801 and 965–980 nm) corresponding to the emission range of laser diodes. The peak absorption cross section σ_a for the band peaked at λ=970.4 nm is 0.15×10^?20 cm². On the basis of the analysis of the absorption and luminescence spectra at low (6 and 12 K) temperatures, the structure of the Stark splitting of erbium levels was determined as a structure of quasi-centers for which Stark components are inhomogeneously broadened. The oscillator strengths of the transitions from the ground state of erbium to excited multiplets were calculated from the absorption spectra measured at T=300 K, and the intensity parameters Ω_t were determined by the Judd-Ofelt method: Ω₂=1.65×10^?20 cm², Ω₄=0.56× 10^?20 cm², and Ω₆=1.01×10^?20 cm². These values of the intensity parameters were used to calculate the probabilities of radiative transitions and the branching ratios. The rates of multiphonon nonradiative transitions in NYF: Er were estimated. The luminescence decay kinetics for radiative levels of erbium ions upon their selective excitation by nanosecond laser pulses was studied. The intracenter lifetimes of radiative levels of erbium ions were determined from the luminescence kinetics upon selective ion excitation by low-intensity light in a sample with a low erbium concentration (0.5%). It is demonstrated that, with an increase in temperature from 6 to 300 K, luminescence from the ⁴ G _11/2, ² G(H)_9/2, and ⁴ F _9/2 levels is quenched as a result of multiphonon nonradiative transitions. Luminescence from the ⁴ I _9/2 level is quenched only insignificantly with increasing temperature, and no quenching of luminescence from the ⁴ I _11/2 and ⁴ I _13/2 levels is observed. The spectra of steady-state luminescence of NYF:Er(0.5–15%) crystals were investigated upon broadband excitation by UV and UV-visible lamp light and selective time-resolved laser excitation. It is shown that low-lying levels of erbium ions separated by an energy gap smaller than 2500 cm^?1 are populated via cascade mechanisms. On the basis of the results obtained, it is concluded that NYF:Er ³⁺ crystals are promising candidates for active media of tunable diode-pumped lasers.     

Polarized absorption spectra and spectroscopic parameters of Tm3+ in the TmAl3(BO3)4 single crystal

High-optical-quality single crystals of the TmAl₃(BO₃)₄ compound were synthesized from a solution in the melt. The absorption spectra in the σ and π polarizations for the ³ H ₆ → ³ F ₄, ³ H ₆ → ³ H ₅, ³ H ₆ → ³ H ₄, ³ H ₆ → ³ F ₃, ³ H ₆ → ³ F ₂, ³ H ₆ → ¹ G ₄, and ³ H ₆ → ¹ D ₂ transitions in the Tm³⁺ ion were recorded at room temperature. The transition intensities were analyzed in the framework of the Judd-Ofelt theory generalized to the case of anisotropic crystals, and the following parameters of the theory were obtained: Ω₂ = 6.14 × 10^?20 cm², Ω₄ = 3.09 × 10^?20 cm², and Ω₆ = 2.04 × 10^?20 cm². The lifetimes and the branching ratios were determined for all possible transitions.     

Intensity parameters for Er<Superscript>3+</Superscript> ions in calcium-niobium-gallium garnet crystals

Based on the analysis of the absorption spectra of Er-doped calcium-niobium-gallium garnet (Er:CNGG) crystals according to the Judd-Ofelt theory, the intensity parameters for these crystals are determined to be Θ₂ = 3.43 × 10^?20 cm² Θ₄ = 1.20 × 10^?20 cm², and Θ₆ = 0.58 × 10^?20 cm². The parameters found are compared with the intensity parameters for other laser oxide crystals. Using these intensity parameters, the probabilities of radiative transitions between the energy levels of Er³⁺ ions in CNGG crystals and the luminescence branching ratios β_JJ’ are calculated. From the measured lifetime of the ⁴ I _11/2 level of Er³⁺ ions (τ = 626 μs) and the probability of the radiative transition from this level (A = 192 s^?1), it is found that about 88% of the excitation energy in the Er:CNGG crystals is nonradiatively transferred from the ⁴ I _11/2 to the ⁴ I _13/2 level. It is suggested that an increase in the oscillator strength and in the line strength of the ⁴ I _15/2 → ² H _11/2 transition of Er³⁺ in CNGG crystals, as well as an increase in the intensity parameter Θ₂ with respect to the corresponding parameters for other garnet crystals are caused by the existence in CNGG crystals of Er³⁺ centers with the environment symmetry lower than D ₂.     

Spectroscopic Study of Neodymium-Doped Sodium–Yttrium Double Fluoride Nd<Superscript>3+</Superscript>:Na<Subscript>0.4</Subscript>Y<Subscript>0.6</Subscript>F<Subscript>2.2</Subscript> crystals

Nd³⁺:Na_0.4Y_0.6F_2.2 (Nd³⁺:NYF) crystals are grown by the Stockbarger–Bridgman method for a stoichiometric mixture prepared by the solid-phase method and containing neodymium up to 20 at. %. The absorption spectrum of Nd³⁺:NYF crystals exhibits bands located in the emission region of laser diodes. The peak absorption cross section of the 796.8-nm band is σ _a = 0.96 × 10^–20 cm² and the bandwidth is Δλ = 17.5 nm. The most intense luminescence band is located at 1.05 μ m and the radiative time of the ⁴F_3/2 level is τ₀ = τ_exp ~ 960 μ s. It is shown that the ²P_3/2 and ⁴D_3/2 levels of Nd³⁺:NYF crystals are also radiative with lifetimes τ exp equal to ~110 and 9.5 μ s, respectively. However, these radiative transitions are partially quenched due to nonradiative relaxation. The intensity parameters Ω t are determined by the Judd–Ofelt method to be Ω₂ = 1.18 × 10^–20, Ω₄ = 1.55 × 10^–20, and Ω 6 = 2.85 × 10–20 cm 2. Using these parameters, the probabilities of radiative transitions and branching ratios are calculated, and the probabilities of nonradiative transitions are estimated. A conclusion is made that Nd³⁺:NYF crystals are promising as active media for diode-pumped tunable lasers, in particular, up-conversion-pumped lasers.     

一种新型掺铒碲酸盐玻璃的光谱性质研究

研究了一种新型掺Er³⁺碲酸盐玻璃的光谱性质；应用Judd-Ofelt理论计算了碲 酸盐玻璃中Er³⁺离子的强度参数Ω(Ω₂=479×10^-20 cm²,Ω₄= 152×10^-20cm²,Ω₆=066×10^-20cm2)，计算了离子的自发跃迁概 率，荧光分支比；应用McCumber理论计算了Er³⁺的受激发射截面(σ_{e=1040×1 0^-21cm²)，Er³⁺离子⁴I13/ 2→⁴I15/2发射谱的 荧光半高宽(FWHM=655nm)及各能级的荧光寿命(⁴I13/2 能级为τrad =399ms)；比较了不同基质玻璃以及不同类型碲酸盐玻璃中Er³⁺离子的光谱 特性， 结果表明该掺铒碲酸盐玻璃具有更好的光谱性能，更适合于掺Er³⁺光纤放大 器实现宽带和高增益放大. 关键词： 碲酸盐玻璃 光谱性质 Judd-Ofelt理论}     

Spectroscopic characteristics of praseodymium-doped cubic double sodium-yttrium fluoride crystals Na0.4Y0.6F2.2:Pr3+. Intensities of optical transitions and luminescence kinetics

Using the Bridgman-Stockbarger technique, we have grown a series of cubic crystals Na_0.4Y_0.6F_2.2:Pr³⁺ (NYF:Pr³⁺) with a content of praseodymium in the range of 0.04–9 at %. We have determined the composition of crystals, evaluated their optical quality, and found the incorporation coefficient of Pr³⁺ ions into the Na_0.4Y_0.6F_2.2 matrix (K _Pr ～ 0.9). We have examined optical spectra of NaYF:Pr³⁺ crystals at room and low (7 K) temperatures in the range of 200–2500 nm. The low-temperature absorption spectra of NYF:Pr³⁺ crystals have been shown to consist of broad weakly structured bands. Based on the analysis of low-temperature absorption spectra, the structure of the Stark splitting of praseodymium levels has been represented in terms of a model of “quasi-centers,” which are characterized by an inhomogeneous broadening of Stark components. From experimental absorption cross-section spectra at T = 300 K, we have calculated oscillator strengths for transitions from the ground state ³ H ₄ to excited multiplets ³ H ₅, ³ H ₆, ³ F _j (j = 2, 3, 4), ¹ G ₄, ¹ D ₂, and (³ P _j ,¹ I ₆) (j = 0, 1, 2). Using the Judd-Ofelt method, we have determined intensity parameters Ω _t and found that Ω₂ = 0, Ω₄ = 4.4 × 10^?20, and Ω₆ = 2.28 × 10^?20 cm². With these values, we have calculated the probabilities of radiative transitions, the branching coefficients, and the lifetimes of the radiative levels ¹ D ₂ and ³ P ₀. The probabilities of multiphonon nonradiative transitions in NYF:Pr³⁺ crystals have been estimated. Using the method of kinetic spectroscopy with selective excitation, we have investigated the luminescence decay kinetics of praseodymium from the ³ P ₀ and ¹ D ₂ levels upon their selective resonant excitation by nanosecond laser pulses. The inference has been made that Na_0.4Y_0.6F_2.2:Pr³⁺ crystals are processable; admit doping by praseodymium in high concentrations; and, with respect to all their radiative characteristics, can be potentially considered as active media for converters of optical radiation and solid-state continuously tunable lasers in the visible range.     

Polarized spectral properties of Nd3+ ions in CaYAlO4 crystal

Nd:CaYAlO₄ single crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). The polarized absorption spectra, the polarized fluorescence spectra, and the fluorescence decay curve of the crystal were measured at room temperature. The spectroscopic parameters were determined by Judd–Ofelt theory and Fuchtbauer–Ladenburg formula. The effective intensity parameters Ω ₂, Ω ₄, and Ω ₆ were obtained to be 2.19, 8.16, and 8.57×10^?20 cm², respectively. The calculated radiative probabilities, branching ratios, and radiative lifetime were also evaluated for the ⁴F_3/2 excited state using the calculated intensity parameters. The results indicate Nd:CaYAlO₄ has potential as a laser gain medium for ultrashort laser system.     

Optical properties of Tm,Mg:LiTaO3 laser crystal

A Tm, Mg co-doped LiTaO₃ crystal has been grown by Czochralski method. Room temperature polarized absorption spectra and fluorescence spectrum of the Tm, Mg:LiTaO₃ crystal were measured and analyzed. The maximum absorption cross-section is 6.0791 × 10⁻²⁰ cm² at around 790 nm with full width at half maximum of 5 nm. The emission cross-section of ³ F ₄ manifold was 2.2 × 10⁻²⁰ cm². The spectroscopic parameters of Tm³⁺ ion were calculated by applying the Judd-Ofelt approach, and the intensity parameters Ω₂, Ω₄, and Ω₆ were obtained to be 7.71 × 10⁻²⁰, 1.09 × 10⁻²⁰, and 1.16 × 10⁻²⁰ cm², respectively. The branching ratios and radiative lifetimes were also presented and the radiative lifetime of Tm^{3+ 3} F ₄ → ³ H ₆ transition is 968.3 μs. The results were also analyzed and compared with other Tm³⁺ doped hosts.     

Spectroscopic and photoluminescence properties of Ho doped Ba0.65Sr0.35TiO3 nanocrystals

Ho³⁺ doped Ba_0.65Sr_0.35TiO₃ (BST) nanocrystals was prepared by sol-gel method. The structural and morphological properties of the nanocrystals were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The absorption spectrum, photoluminescence spectrum and fluorescence time decay curve were measured at room temperature. Based on the Judd-Ofelt (J-O) theory, the J-O intensity parameters Ω_t (t=2, 4, 6) of Ho³⁺ doped BST nanocrystals were calculated to be 0.67×10⁻²⁰ cm², 1.11×10⁻²⁰ cm² and 1.09×10⁻²⁰ cm², respectively. The emission probabilities, radiative lifetimes and branching ratios of the different Ho³⁺ transitions were also determined. The emission cross sections of the important intermanifold transitions ⁵F₄,⁵S₂→⁵I₈, ⁵F₅→⁵I₈ and ⁵F₄→⁵I₇ have been calculated from the luminescence spectrum. The room temperature fluorescence lifetime of the ⁵S₂→⁵I₈ transition for Ho³⁺ in BST nanocrystals was measured and the radiative quantum efficiency was estimated to be 61.9%.     

Absorption of Dy3+ and Nd3+ ions in BaR 2F8 single crystals

The Dy³⁺ absorption and excitation spectra of BaY₂F₈ and BaYb₂F₈ single crystals are investigated in the ultraviolet, vacuum ultraviolet, and visible ranges at a temperature of 300 K. These crystals exhibit intense broad absorption bands due to the spin-allowed 4f-5d transitions in the range (56–78) × 10^?3 cm^?1 and less intense absorption bands that correspond to the spin-forbidden transitions in the range (50–56) × 10^?3 cm^?1. The Nd³⁺ absorption spectra of BaY₂F₈ single crystals are studied in the range (34–82) × 10^?3 cm^?1 at 300 K for different crystal orientations.     

Tm3+/Yb3+共掺铋碲酸盐玻璃中的高效蓝色上转换荧光

制备了高折射率Tm³⁺/Yb³⁺共掺杂铋碲酸盐玻璃，利用棱镜耦合法测量出玻璃在632.8和1550nm波长处的折射率分别为2.0365和1.9795. 对玻璃的吸收、荧光和红外透过光谱展开了测试与分析，根据Judd-Ofelt理论对吸收光谱进行拟合，求得Tm³⁺的振子强度参数Ω_t(t=2，4，6)分别为3.90×10^-20, 2.03×10^-20和9.03×10^{-2 关键词： 3+}/Yb³⁺共掺')" href="#">Tm³⁺/Yb³⁺共掺 铋碲酸盐玻璃 光谱参数 上转换荧光     

Field ion microscopy of cascades of atomic displacements in metals and alloys after various types of irradiation

Experimental results on atomic-spatial investigation of radiative defect formation in surface layers of materials, initiated by neutron bombardment (of Pt, E > 0.1 MeV) and ion implantation (in Cu₃Au: E = 40 keV, F = 10¹⁶ ion/m², j = 10^?3 A/cm²), are considered. Quantitative estimates are obtained for the size, shape, and volume fraction of cascades of atomic displacements formed under various types of irradiation in the surface layers of the materials. It is shown that the average size of radiation clusters after irradiation of platinum to a fast neutron fluence of 6.7 × 10²² m^?2 (E > 0.1 MeV) is about 3.8 nm. The experimentally established average size of a radiation cluster (disordered zone) in the alloy after ion bombardment is 4 × 4 × 1.5 nm.     

ANISOTROPY OF OPTICAL ABSORPTION INTENSITY IN Tm3+ DOPED YVO4 CRYSTALS

Seven absorption group-bands (¹D₂, ¹G₄, ³F₂, ³F₃, ³H₄, ³H₅, ³F₄) of Tm³⁺ in YVO₄ single crystals have been observed in the orientation absorption spectra recorded in the spectral range from 200 to 4000 nm at 300K. The integrated absorption cross section for each group-band was accurately evaluated. On the assumption that the anisotropy of this uni-axial crystal is small, the Judd-Ofelt theory was extended for the calculation of 4f-4f transition intensities of Tm³⁺ in YVO₄. Two sets of phenomenological intensity parameters were derived from a least-squares-fit procedure. For c-axis cut sample we have Ω₂=10.18 (10^-20cm²), Ω₄=1.96 (10^-20cm²), Ω₆=0.75 (10^-20cm²).For a-axis cut sample we have Ω₂=8.20 (10^-20cm²), Ω₄=2.47 (10^-20cm²), Ω₆=0.91 (10^-20cm²). The anisotropy of the optical absorption intensities of Tm³⁺:YVO₄ was theoretically analyzed in detail.     

Spin-spin interaction of Dy3+ ions in KY(WO4)2

The spin-spin interaction of Dy³⁺ ions in a KY(WO₄)₂ single crystal is investigated by electron paramagnetic resonance (EPR) spectroscopy at a temperature of 4.2 K and a frequency of 9.2 GHz. The EPR spectra of ion pairs located in different coordination shells are analyzed. It is revealed that the considerable contribution to the spin-spin interaction of the nearest neighbor ion pair nn is made not only by the magnetic dipole-dipole interaction but also by the isotropic exchange interaction with the parameter I _nn = (+601 ± 17) × 10^?4cm^?1. The exchange interaction in pairs of more widely spaced ions is substantially weaker: I _5n = (?38 ± 3) × 10^?4cm^?1 and I _9n = (+18 ± 4) × 10^?4cm^?1. For the other ion pairs, the magnetic dipole-dipole interaction dominates. It is found that the EPR spectra of single ions and ion pairs exhibit a superhyperfine structure associated with tungsten nuclei.     

Variation of potential energy surface height and bound state depth induced by laser phase along the reaction path in atom-molecule reactions: Application to Li + CH<Subscript>4</Subscript> → LiH + CH<Subscript>3</Subscript>

Laser atom-molecule reaction interaction through polarizability and dipole moment contribution leads to potential energy surface barrier reshaping and bound states along the reaction path. The polarizability is maximum in the transition state. We will show here by using gauge representation (electric field gauge) for wave length λ = 20.6 μm, intensity I = 1 × 10¹² W/cm², I = 5 × 10¹² W/cm², I = 1 × 10¹³ W/cm², I = 3 × 10¹³ W/cm², that we can create laser induced potential energy surface barrier reshaping in the transition state region (–1–0.5 a. u.). We illustrate such effects for the LiH + CH₃ ? Li + CH₄ reaction with a barrier using ab-initio methods for calculating the reaction path, polarizability and dipole moment contribution of the atom-molecule reaction.     

Optical spectra and emission characteristics of terbium-doped potassium–lead double chloride crystals (KPb<Subscript>2</Subscript>Cl<Subscript>5</Subscript>:Tb<Superscript>3+</Superscript>)

Optical transitions in KPb₂Cl₅:Tb³⁺ crystals are studied experimentally and theoretically. The absorption cross-section spectra are plotted and the oscillator strengths of transitions from the ground terbium state to excited multiplets are determined. Intensity parameters Ω_t for KPC:Tb³⁺ are determined by the Judd–Ofelt method to be Ω₂ = 2.70 × 10^–20 cm², Ω₄ = 7.0 × 10^–20 cm², and Ω₆ = 0.72 × 10^–20 cm². These values were used to calculate such characteristics of spontaneous radiative transitions as oscillator strengths, probabilities of radiative transitions, and radiative lifetimes. The emission spectra of KPb₂Cl₅:Tb³⁺ crystals upon UV excitation and the decay kinetics of luminescence from the excited ⁵ D ₃ and ⁵ D ₄ levels are studied experimentally, the lifetimes of these levels are determined, and the dependences of the rates of nonradiative relaxation from the excited ⁷ F _j (j = 0–5), ⁵ D ₄, and ⁵ D ₃ levels to lower-lying terbium levels are calculated. It is shown that the population of the ⁵ D ₄ level in KPC:Tb³⁺ crystals occurs according to a cascade scheme, which leads to quenching of the ⁵ D ₃ level. The calculated data agree well with the known experimental rates of multiphonon nonradiative transitions for Dy:KPC, Nd:KPC, Er:KPC, Tb:KPB, and Nd:KPB crystals. It is shown that transitions in the near-IR (3–6 μm) region in double halide crystals (MPb₂Hal₅) are almost unquenched and the rates of nonradiative relaxation of excited levels spaced by energy gaps ΔE _ji > 1000 cm^–1 are W _ji ^NR < 10³s^–1. This circumstance suggests that it is possible to obtain stimulated emission in KPb₂Cl₅:RE³⁺ crystals in the IR spectral region up to 6 μm.     

掺铒铋酸盐玻璃的光谱性质研究

研究了掺铒铋酸盐玻璃的吸收和荧光光谱性质,应用Judd-Ofelt理论计算了玻璃的三个强度参量Ω_t=(t=2,4,6),分别为Ω₂=3.71×10^-20cm²,Ω₄=1.86×10^-20cm²,Ω₆=1.28×10^-20cm²,计算了Er³⁺离子的自发跃迁几率、荧光分支比等光谱参量.经荧光谱测试发现掺Er³⁺铋酸盐玻璃的荧光半高宽可达70nm.应用McCumber理论计算1.53μm处的受激发射截面可达9×10^-21cm².对Er³⁺离子在不同基质玻璃中光谱特性的比较发现,Er³⁺在铋酸盐玻璃中具有相对较高的受激发射截面和宽的荧光半高宽.     

Crystalline structure and optical spectroscopy of Er3+-doped KGd(WO4)2 single crystals

4 )₂ single crystals doped with Er³⁺ have been grown by the flux top-seeded-solution growth method. The crystallographic structure of the lattice has been refined, being the lattice constants a=10.652(4), b=10.374(6), c=7.582(2) Å, β=130.80(2)°. The refractive index dispersion of the host has been measured in the 350–1500 nm range. The optical absorption and photoluminescence properties of Er³⁺ have been characterised in the 5–300 K temperature range. At 5 K, the absorption and emission bands show the (2J+1)/2 multiplet splittings expected for the C₂ symmetry site of Er in the Gd site. The energy positions and halfwidths of the 72 sublevels observed have been tabulated as well as the cross sections of the different multiplets. Six emission band sets have been observed under excitation of the ⁴F_7/2 multiplet. The Judd–Ofelt (JO) parameters of Er³⁺ in KGW have been calculated: Ω₂=8.90×10^-20 cm², Ω₄=0.96×10^-20 cm², Ω₆=0.82×10^-20 cm². Lifetimes of the ⁴S_3/2, ⁴F_9/2, and ⁴I_11/2 multiplets have been measured in the 5–300 K range of temperature and compared with those calculated from the JO theory. A reduction of the ⁴S_3/2 and ⁴I_11/2 measured lifetimes with increasing erbium concentration has been observed, moreover the presence of multiphonon non-radiative processes is inferred from the temperature dependence of the lifetimes. Received: 15 December 1997/Revised version: 10 July 1998