Erbium doped Bi2O3-B2O3 glass-ceramics containing Bi3B5O12 and CaF2 nanocrystallites for 1.53 μm fiber lasers

Trivalent erbium ions doped Bi₂O₃-B₂O₃ transparent glass ceramics containing CaF₂ were prepared and characterized through X -ray diffraction, scanning electron microscopy, Fourier transform infrared absorption, optical absorption, and near infrared emission for 1.53 μm fiber lasers. The glass ceramics obtained by applying thermal treatment at 575 °C for 5 h and 575 °C for 10 h contain Bi₃B₅O₁₂ and CaF₂ crystallites. The Judd-Ofelt theory was applied to evaluate various spectroscopic and laser characteristic properties. The NIR emission corresponding to the ⁴I_13/2 → ⁴I_15/2 (∼1.53 μm) transition was studied by exciting the samples at 514.5 nm laser radiation. The stimulated emission cross-sections of ∼1.53 μm luminescence were also obtained applying the Mc Cumber theory. The experimental results confirm that the transparent glass ceramic obtained at a thermal treatment of 575 °C for 10 h is more suitable to design fiber lasers for diverse applications in the fields of industry, medicine and scientific research.     

Enhanced visible green and 1.5 μm radiative emission of Er~(3+) ions in Li_2O-PbO-Al_2O_3-B_2O_3 glasses for photonic applications

A series of Er~(3+) ions doped lithium lead alumino borate(LiPbAlB) glasses were synthesized via melt quench method and their structural,physical and optical properties were studied.Judd-Ofelt theory in correlation with the emission and absorption profiles was performed for the measurement of various radiative parameters for different transitions of Er~(3+) doped glasses.The as-prepared glasses show deep green(550 nm) as well as NIR(1532 nm) emission at 380 and 980 nm excitation wavelengths,respectively.The intensity of emission spectra increases with Er~(3+) ions concentration up to 1.5 mol% and beyond quenching is observed.The Dexter theory applied to the emission profiles reveals the interaction between Er~(3+)ions as dipole-dipole in nature.CIE color coordinates are found to fall in the green region of the visible spectrum.It is observed that 1.5 mol% of Er~(3+) ions concentration is optimum to exhibit the maximum quantum efficiency,branching ratios,gain bandwidth,emission cross-section,gain crosssection and aptly suitable for visible and NIR photonic applications.     

A study on fluorescence properties of Eu3+ ions in alkali lead tellurofluoroborate glasses

Glasses with chemical composition of (in mol.%): 26 RF-20 PbO-10 TeO2-43 H3BO3-1 EuO3 (RLTB) were prepared by conventional melt quenching method. The Judd-Ofelt intensity parameters Ω2 and Ω6 were obtained from the absorption intensities of 7F0→5D2 and 7F0→5L6 transitions, respectively. In order to overcome the problem of applicability of Judd-Ofelt analysis at room temperature due to the overlapping of the transitions originating from 7F0 and 7F1 levels of Eu3+ ion, the effect of the thermalization on the population of energy levels was taken into account. The photoluminescence spectra contained five emission bands originating from the 5D0 metastable state to 7FJ (J=0, 1, 2, 3, 4) lower lying states. The decay profiles were found to be single exponential in all the three glasses. The measured lifetimes (τmes) were in good agreement with the calculated lifetimes (τcal) obtained by using the thermally corrected Judd-Ofelt intensity parameters.     

Fluorescence properties and energy transfer mechanism of Sm ion in lead telluroborate glasses

We report the fluorescence properties of Sm³⁺-doped lead telluroborate glasses of composition PbF₂.TeO₂.H₃BO₃.Sm₂O₃ as a function of Sm³⁺ concentration. A Judd-Ofelt scheme was used to determine the intensity parameters and radiative properties of Sm³⁺ ion. The emission and decay measurements were carried out at 402 nm excitation. Beyond 1.0 mol% Sm³⁺ concentration, the luminescence quenching is observed. The decay curves of ⁴G_5/2 level are well fitted to a single exponential function. The evaluated radiative properties suggest that the ⁴G_5/2 → ⁶H_7/2 transition is responsible for reddish-orange luminescence which might be used in the development of visible lasers.     

Structure,Judd-Ofelt analysis and spectra studies of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg,Ca, Sr,Ba) glasses for reddish-orange light application

In the present work, a series of Sm³⁺-doped MO-ZnO-B₂O₃–P₂O₅ (M = Mg, Ca, Sr, Ba) glasses were prepared. The glass structure and luminescence properties were investigated by XRD, DSC, IR, absorption spectroscopy, Judd-Ofelt theory and photoluminescence spectra. The J-O parameters of Sm³⁺-doped glasses follow the trend of Ω₄＞Ω₆＞Ω₂. Under the excitation of 401 nm Xenon lamp, Sm³⁺-doped glasses exhibited four emissions from the transitions of ⁴G_5/2→⁶H_J/2 (J = 5, 7, 9, 11) in the visible spectra. The luminous intensity of Sm³⁺ increases with the asymmetry in local environments and decreases with the increasing radius of the alkaline-earth cation. Among the as-prepared glass, the Sm³⁺-doped glass containing magnesium oxide exhibits higher values of stimulated emission cross-section (2.18 × 10⁻²¹ cm²), gain bandwidth (1.40 × 10⁻²⁷ cm³), and optical gain (3.83 × 10⁻²⁴ cm²). All the Sm³⁺-doped glasses show intense orange light in the CIE 1931 chromaticity diagram with a high color purity exceeding 99%. In addition, the time-resolved emission spectra reveal the decay process of the Sm³⁺ ions for the transitions ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 in the glass containing magnesium oxide. It suggests that Sm³⁺-doped alkaline-earth zinc borophosphate glasses could be a potential candidate for reddish-orange light-conversion fluorescent materials based on the ultraviolet light-emitting diode.     

Effects of Different Ligands on Fluorescent Properties of Nd3+ Organic Complexes

合成了4种掺Nd3+的配合物分别是Nd(C2F5COO)3Tfpy,Nd(C3F7COO)3Tfpy,Nd(C2F5COO)2(C6F5COO)Tfpy和Nd(C2F5COO)3Phen,来研究不同的配体对配合物发光性能的影响。通过紫外吸收谱、红外光谱和核磁共振H谱表征了配合物的结构。在吸收谱、荧光谱和辐射寿命的基础上,应用Judd-Ofelt理论对4种配合物进行了分析。结构分析表明配体和中心的钕离子均成功配位。JO理论分析得到较小的?2表明钕离子和配体是通过离子键的形式配合的。配合物中的环状结构可以显著地提高钕离子的荧光量子效率。与常用的第二配体Phen相比,Tfpy由于自身较小的对称性和含较少的H原子而成为更好的中性第二配体。本研究合成的4种配合物都有较大的受激辐射面积,可以作为潜在的液体激光材料。     

Composition and concentration dependence of spectroscopic properties of Nd-doped tellurite and metaborate glasses

The spectroscopic properties of tellurite glasses of composition (in mol%) TNKNd: (70 − x)TeO₂-15Nb₂O₅-15K₂O-xNd₂O₃ (x = 0.1, 1.0, 1.5, 2.0 and 2.5) and TNLNd10: 69TeO₂-15Nb₂O₅-15Li₂O-1.0Nd₂O₃ and lithium metaborate glass of composition LBNNd10: 89LiBO₂-10Nb₂O₅-1.0Nd₂O₃ have been investigated using absorption and emission spectra and decay curve analysis. An energy level analysis has been carried out considering the experimental energy positions of the absorption and emission bands, using the free-ion Hamiltonian model. The spectral intensities have been calculated by using the Judd-Ofelt theory and in turn the radiative properties such as radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes have been estimated. The decay curves at the lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (?1.0 mol%) due to energy transfer processes. The effective lifetimes for the ⁴F_3/2 level are found to decrease with increase in Nd₂O₃ concentration for all the glasses under investigation. The non-exponential decay curves have been well-fitted to the Yokota-Tanimoto model with S = 6, indicating that the nature of energy transfer is of dipole-dipole type and energy migration also plays an important role. The results obtained have been compared with Nd³⁺-doped phosphate, fluorophosphate, lead borate, tellurite, germanate and silicate glasses and Nd³⁺-doped YAG ceramic and Ca₂Nb₂O₇ crystals.     

Spectral parameters of Nd3+ ion in Nd:KLa(WO4)2 crystal

The spectral parameters of Nd³⁺ ions in Nd:KLa(WO₄)₂ crystal have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the parameters of oscillator strengths are Ω₂=3.0887×10^–20 cm², Ω₄=1.0375×10^–20 cm², Ω₆=1.0422×10^–20 cm², the radiative lifetime is 685 μs, the quantum efficiency is 30.7%, and the fluorescence branch ratios were calculated: β₁=0.432, β₂=0.475, β₃=0.089, β₄=0.004. Electronic Publication     

Effects of substitution of BaF2 for GdF3 on optical properties of dense oxyfluoride borogermanate scintillating glasses

Eu3+-activated B2O3-GeO2-37Gd2O3-3Eu2O3-(15–x)GdF3-xBaF2 (0≤x≤15) scintillating glasses with the density of 6.1–6.3 g/cm3 were synthesized by a melt-quenching method. The substitution of BaF2 for expen...     

Novel Tm-doped fluorotellurite glasses with enhanced quantum efficiency

In this paper, new highly Tm³⁺-doped tellurite glasses with host composition 75TeO₂-xZnF₂-yGeO₂-12PbO-3Nb₂O₅ [x(5-15), y(0-5) mol%] are presented and compared to the Tm-doped tellurite glasses based on the traditional host composition: 75TeO₂-20ZnO-5Na₂O mol%. Enhanced quantum efficiency from ³F₄ level was observed for the proposed glasses and thermal stability and viscosity values make them suitable for optical fiber drawing. Besides the host composition, substantial influence of Tm³⁺ concentration on luminescence and lifetime of excited ³F₄ and ³H₄ states were discussed.