Structural and luminescence properties of Dy3+ ion in strontium lithium bismuth borate glasses

Different concentrations of dysprosium doped strontium lithium bismuth borate (SLBiB) glasses were synthesized by the conventional melt quenching method and characterized through X-ray diffraction, Raman, absorption and visible luminescence spectroscopies. These Dy³⁺ doped glasses are studied for their utility for white light emitting diodes. X-ray diffraction studies revealed amorphous nature of the studied glass matrices. Coexistence of trigonal BO₃ and tetrahedral BO₄ units was evidenced by Raman spectroscopy. From the absorption spectra, Judd–Ofelt (J–O) intensity parameters, Ω_λ (λ=2, 4 and 6), have been calculated. The hypersensitivity of the transition, ⁶H_15/2→⁶F_11/2 of Dy³⁺ has been discussed based on the magnitude of Ω₂ parameter. Using J–O intensity parameters, several radiative properties such as spontaneous transition probabilities (A_R), radiative branching ratios (β_R) and radiative lifetimes (τ_R) have been determined. From the emission spectra, a strong blue emission that corresponds to the transition, ⁴F_9/2→⁶H_15/2, was observed and it also shows combination of blue, yellow and red emission bands for these glasses. In addition to that, white light emission region have been observed from these studies.     

Absorption and luminescence spectral analysis of Dy3+-doped magnesium borate glass

This paper reports the luminescence potential of the dysprosium ion (Dy³⁺)-doped (varying contents from 0.1 to 1.0 mol%) magnesium borate glasses prepared by the melt-quenching method. As-quenched samples were characterized systematically to determine the effects of various Dy³⁺ contents on their structure, physical and optical traits. The Judd−Ofelt (J−O) intensity parameters (Ω₂, Ω₄, Ω₆) and radiative properties of the best sample (with 0.7 mol% of Dy³⁺ doping) was evaluated to complement the experimental optical data. The studied glasses revealed three luminescence emission peaks at 382 nm (⁴F_9/2→⁶H_15/2, intense Blue), 572 nm (⁴F_9/2→⁶H_15/2, intense Yellow) and 661 nm (⁴F_9/2→⁶H_11/2, weak Red) under the excitation wavelength of 347 nm. The emission intensity was first increased up to the Dy³⁺ content of 0.7 mol% and then quenched. The observed luminescence intensity quenching was due to the resonant energy transfer from the excited state to the neighbouring ground state of Dy³⁺. The obtained high value of Ω₂ signified the strong degree of covalency between the Dy³⁺ and ligand environment. The optimum glass sample (with 0.7 mol% of Dy³⁺) showed higher values of the branching ratio and stimulated emission cross-cross section for the ⁴F_9/2→⁶H_15/2 (yellow) emission transition, indicating its potential as bright yellow luminescent material and high gain visible laser applications.     

Absorption and fluorescence studies of Sm ions in lead containing sodium fluoroborate glasses

Lead containing calcium zinc sodium fluoroborate glasses (LCZSFB) with molar composition of 20PbO+5CaO+5ZnO+10NaF+(60−x) B₂O₃+x Sm₂O₃, (x=0.1, 0.25, 0.5, 1.0 and 2.0 mol%) were prepared and investigated by the XRD, FTIR, optical absorption, photoluminescence and decay curve analysis. Judd-Ofelt theory was applied to the experimental oscillator strengths to evaluate the phenomenological J-O intensity parameters Ω_λ (λ=2, 4 and 6). Using the J-O intensity parameters as well as from the emission and decay measurements, various radiative parameters such as transition probabilities (A_R), radiative lifetimes (τ_R), measured lifetimes (τ_m), calculated branching ratios (β_R), measured branching ratios (β_m), effective bandwidth (Δλ_eff) and stimulated emission cross sections σ(λ_p) have been calculated for the excited ⁴G_5/2 luminescent level. The nature of decay curves of ⁴G_5/2 level for different Sm³⁺ ion concentrations in all LCZSFB glasses has been analyzed and the lifetimes are noticed to decrease with increase of concentration. The concentration quenching has been attributed to the energy transfer through the cross-relaxation between Sm³⁺ ions. Based on these results, the utility of Sm³⁺ ions doped lead containing fluoroborate glasses as laser active materials in the visible region is discussed.     

Investigation on luminescence properties of Nd ions in alkaline-earth titanium phosphate glasses

Nd³⁺ ions doped alkaline-earth titanium phosphate glasses were prepared by using the conventional melt quenching method. Absorption spectra were recorded and oscillator strengths of the transitions were calculated using area under the absorption bands. The energy level analysis was carried out by using free-ion Hamiltonian model. The three host dependent Judd-Ofelt intensity parameters, Ω_λ (λ = 2, 4, and 6) were used to elucidate the structure of glassy matrix around Nd³⁺ ion as well as to determine the ⁴F_3/2 metastable state radiative properties such as radiative transition probabilities, branching ratios and radiative lifetimes. The decay curves of all the three glasses show single exponential behavior. The discrepancy between the experimental and calculated lifetimes of emitting level was attributed to multiphonon relaxation. The achieved high quantum efficiencies for the ⁴F_3/2 level indicate efficient laser emission at 1.06 μm in these glass systems.     

Optical properties of Er:SrMoO4 single crystal

Er³⁺:SrMoO₄ crystal of high optical quality was grown by the Czochralski method. The room temperature polarized absorption and emission spectra together with the lifetime decay curve were measured. Based on the Judd-Ofelt theory, three intensity parameters, radiative transition rates, radiative lifetimes and fluorescent branching ratios, were obtained. Emission cross-section and gain cross-section around 1.54 μm were also obtained.     

Structural and photoluminescence properties of Dy3+ doped different modifier oxide-based lithium borate glasses

Structural and photoluminescence properties of Dy³⁺ doped lithium fluoro-borate glasses with the compositions Li₂B₄O₇–BaF₂–NaF–MO (where M=Mg, Ca, Cd and Pb), Li₂B₄O₇–BaF₂–NaF–MgO–CaO and Li₂B₄O₇–BaF₂–NaF–CdO–PbO have been investigated through XRD, FTIR, optical absorption, emission and decay measurements. From the optical absorption spectra, Judd–Ofelt intensity parameters (Ω_λ, λ=2, 4 and 6) have been evaluated and are in turn used to predict radiative properties such as radiative transition probabilities (A_T), branching ratios (β_r) and stimulated emission cross sections (σ_p) for all emission levels of Dy³⁺ ion in different lithium fluoro-borate glass matrices. From the emission spectra, chromaticity color coordinates have been calculated and indicated emission color for all glass matrices. The nature of decay profiles of ⁴F_9/2 state of Dy³⁺ in all the glass matrices are analyzed.     

Spectroscopic investigations and luminescence spectra of Nd and Dy doped different phosphate glasses

Spectral properties of Nd³⁺ and Dy³⁺ ions in different phosphate glasses were studied and several spectroscopic parameters were reported. Covalency of rare-earth-oxygen bond was studied in these phosphate glass matrices with the variation of modifier in host glass matrix. Using Judd-Ofelt intensity parameters (Ω₂, Ω₄ and Ω₆), radiative transition probabilities (A) and radiative lifetimes (τ_R) of certain excited states of Nd³⁺ and Dy³⁺ ions are estimated in these glass matrices. From the magnitudes of branching ratios (β_R) and integrated absorption cross-sections (Σ), certain transitions of both the ions are identified for laser excitation. From the emission spectra, peak stimulated emission cross-sections (σ_P) are evaluated for the emission transitions observed in all these phosphate glass matrices for both Nd³⁺ and Dy³⁺ ions.     

Dysprosium doped alkali fluoroborate glasses—Thermal, structural and optical investigations

Thermal, structural and optical properties of Dy³⁺-doped alkali fluoroborate glasses with composition (in mol%), 49B₂O₃+25XO+25NaF+1Dy₂O₃ (where X=Li₂, Na₂, K₂, Mg and Ca), have been investigated. Thermal analysis revealed the homogeneous formation of the glasses. The FTIR spectra reveal that the glasses contain BO₃, BO₄ non-bridging oxygen atoms and strong OH⁻ bonds. From the optical absorption spectra, Judd-Ofelt intensity parameters (Ω_λ, λ=2, 4 and 6) have been evaluated and are in turn used to predict radiative properties such as radiative transition probability (A), stimulated emission cross-section () and branching ratios (β_R) for the excited levels of Dy³⁺ ions in alkali fluoroborate glasses. The dependence of the spectral characteristics of Dy³⁺ ions due to compositional changes has been examined and reported.     

Optical properties of Dy ions in sodium gadolinium tungstates crystal

Dy³⁺-doped NaGd(WO₄)₂ crystal with sizes of about Φ20×40 mm² was grown by the Czochralski technique along the (0 0 1) orientation. Polarized absorption spectra, fluorescence spectra, and fluorescence decay curve of Dy³⁺-doped NaGd(WO₄)₂ have been recorded at room temperature. Based on the Judd-Ofelt (J-O) theory, the intensity parameters from the measured line strengths were evaluated. The J-O parameters were used to predict radiative transition probabilities, radiative lifetimes and branching ratios for various excited levels of Dy³⁺-doped NaGd(WO₄)₂ crystal. The luminescent quantum efficiency of the ⁴F_9/2 level was determined to be approximately 63% for this material. The emission cross-section of the ⁴F_9/2→⁶H_13/2 transition was estimated by using the Füchtbauer-Ladengurg method.     

Absorption and emission properties of Nd in lithium cesium mixed alkali borate glasses

Lithium cesium mixed alkali borate glasses of the composition 67B₂O₃·xLi₂O·(32−x)Cs₂O (where x=8, 12, 16, 20 and 24) containing 1 mol% Nd₂O₃ were prepared by melt quenching. The absorption spectra of Nd³⁺ were studied from the experimental oscillator strengths and the Judd-Ofelt intensity parameters were obtained. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) (A_T), branching ratios (β) and integrated absorption cross-sections (Σ) of the Nd³⁺ transitions from the excited state J manifolds to the lower lying J′ manifolds. Radiative lifetimes (τ_R) are estimated for certain excited states of Nd³⁺ in these mixed alkali borate glasses. Luminescence spectra were measured and the emission cross-sections (σ_p) were evaluated for the three emission transitions. The variation of luminescence intensity with x was recorded for the three transitions at different excitation power to see the effect of mixed alkalies in these borate glasses.     

An investigation on visible luminescence of Ho activated LBTAF glasses

Different concentrations of Ho³⁺-doped lead borate titanate aluminum fluoride (LBTAFHo) glasses with chemical composition of PbO-H₃BO₃-TiO₂-AlF₃-Ho₂O₃ were prepared by the melt quenching method. The spectral properties were investigated using the absorption, emission and decay measurements. The experimental oscillator strengths were calculated from the area under the absorption bands. Applying Judd-Ofelt theory, the intensity parameters (Ω_{λ=2, 4, 6}) were calculated, by the least square fit approach from which the radiative transition rates, luminescence branching ratios and radiative decay times were determined. The photoluminescence spectra revealed the quenching of luminescence intensity beyond 1.0 mol% of Ho³⁺ ion concentration. To investigate the luminescence potentiality of ⁵F₄→⁵I₈ emission level, the effective bandwidth and the stimulated emission cross-section were determined. The quenching in experimental decay time is attributed to the resonance energy transfer among the excited Ho³⁺ ions.     

Judd–Ofelt analysis and improvement of thermal and optical properties of tellurite glasses by adding P2O5

Er³⁺ and Er³⁺/Yb³⁺ co-doped tellurite glasses, suitable for developing optical fiber laser and amplifier, have been elaborated from the conventional melt-quenching method. Results of differential scanning calorimetry (DSC) measurements indicate a good thermal stability of tellurite glasses. The DSC measurements show an improvement of thermal stability of glass hosts after adding P₂O₅. Absorption spectrum from near infrared to visible was obtained and the Judd–Ofelt (J–O) intensity parameters (Ω₂, Ω₄, and Ω₆) were determined. Spontaneous emission probabilities of some relevant transitions, branching ratio, and radiative lifetimes of several excited states of Er³⁺ have been predicted using intensity J–O parameters. Absorption cross-section and calculated emission cross-section, using the McCumber method, for the ⁴I_13/2→⁴I_15/2 transition, were determined and compared for the doped and co-doped glasses. Energy transfer (ET) and effect of changing concentration of P₂O₅ and Yb³⁺ ions on spectroscopic properties were investigated. It was found that the addition of P₂O₅ can increase the symmetry of the Er³⁺ ion. As a consequence, PL lifetime becomes more longer.The spectroscopic properties and the efficient infrared luminescence indicate that Er³⁺ doped TeO₂–ZnO–Na₂O–Er₂O₃(TZNE) is a promising laser and amplifier materials and may be a potentially useful material for developing upconversion fiber optical devices.     

Emission characteristics of Dy3+ ions in lead antimony borate glasses

Glasses with the composition 30PbO–25Sb₂O₃–(45?x)B₂O₃–xDy₂O₃ for x=0 to 1 were prepared in steps of 0.2 by the melt-quenching method. Various physical parameters, viz., density, molar volume, and oxygen packing density, were evaluated. Optical absorption and luminescence spectra of all the glasses were recorded at room temperature. From the observed absorption edges optical band gap, the Urbach energies are calculated; the optical band gap is found to decrease with the concentration of Dy₂O₃. The Judd–Ofelt theory was applied to characterize the absorption and luminescence spectra of Dy³⁺ ions in these glasses. Following the luminescence spectra, various radiative properties, like transition probability A, branching ratio β and the radiative life time τ for different emission levels of Dy³⁺ ions, have been evaluated. The radiative lifetime for the ⁴F_9/2 multiplet has also been evaluated from the recorded life time decay curves, and the quantum efficiencies were estimated for all the glasses. The quantum efficiency is found to increase with the concentration of Dy₂O₃.     

Photoluminescence properties of Eu in lithium titanate

Lithium titanate ceramics doped with Eu were synthesized and their photoluminescence (PL) and emission spectral characteristics were investigated. PL spectra of the sample showed peaks corresponding to the ⁵D₀→⁷F_J (J=0, 1, 2, 3 and 4) transitions under 230 nm excitation. The fluorescence lifetimes of Eu³⁺ ions were found out to be 645 μs. Strong red emission coming from the hypersensitive ⁵D₀→⁷F₂ transition of Eu³⁺ ion suggested the presence of the dopant ion in highly asymmetric environment. Further analysis of the emission spectrum revealed that the symmetry of the metal ion is very low i.e. C₂. The emission intensity of the sample was compared with a commercial phosphor to get an idea about the commercial utility of the phosphor. Various emission properties for the system namely Judd-Ofelt intensity parameters, spontaneous emission probabilities, branching ratios, radiative lifetimes and quantum efficiency were evaluated for the dopant ion by adopting standard procedure.     

Sr2CeO4:Eu and Sr2CeO4:5 mol% Eu, 3 mol% Dy microphosphors: Wet chemistry synthesis from hybrid precursor and photoluminescence properties

In this article, Sr₂CeO₄:x mol% Eu³⁺ and Sr₂CeO₄:5 mol%Eu³⁺, 3 mol% Dy³⁺ phosphors were synthesized from assembling hybrid precursors by wet chemical method. As-prepared samples present uniform grain-like morphology and the particle size is about 0.2 μm. The luminescence spectra of Sr₂CeO₄:x mol% Eu³⁺ have been measured to examine the influence of the intensity of red emission lines for Eu³⁺ on the concentration of Eu³⁺, showing that the intensity of the red emission increases with an increase of the concentration from 1 to 5 mol%. Additionally, from the emission spectra of Sr₂CeO₄:5 mol%Eu³⁺, 3 mol% Dy³⁺ phosphors, the characteristic lines of Dy³⁺ have also been observed. This result indicates that there also exists an energy transfer process between Sr₂CeO₄ and Dy³⁺.     

Ga2O3组分对Tm3+掺杂GeO2-Ga2O3-Li2O-BaO-La2O3玻璃的光谱性能影响

制备了Tm³⁺(8.0mol%)掺杂(77-x)GeO₂-xGa₂O₃-8Li₂O-10BaO-5La₂O₃(x=4,8,12,16)系列玻璃.系统地研究了Ga₂O₃从4mol%变化到16mol%时,玻璃的光谱性质与热学性质的变化规律.差热分析表明,随着Ga₂O₃含量的增加,锗酸盐玻璃的热稳定性增加.运用Judd-Ofelt(J_O)理论计算得到了Tm³⁺在不同Ga₂O₃含量的GeO₂-Ga₂O₃-Li₂O-BaO-La₂O₃玻璃中的J-O强度参数(Ω₂,Ω₄,Ω₆)及Tm³⁺各激发能级的自发跃迁概率、荧光分支比以及辐射寿命等光谱参量.在808nm激光二极管的激发下,测试并分析了Ga₂O₃对Tm³⁺荧光光谱特性的影响.随着Ga₂O₃从4mol%增加到16mol%,Tm³⁺在1.8μm处的荧光强度呈现先减弱后增强的特性.当Ga₂O₃含量大约在12mol%时,Tm³⁺在1.8μm处的荧光强度最弱,受激发射截面达到最小.还初步讨论了Ga₂O₃对玻璃结构与光谱参数的影响规律. 关键词： 3+掺杂锗酸盐玻璃')" href="#">Tm³⁺掺杂锗酸盐玻璃 光谱性能 Judd-Ofelt参数 热稳定性     

Spectral Investigations on Ho3+ Doped Mixed Alkali Chloroborate Glasses

The optical absorption and emission spectra of two different Ho³⁺ doped mixed alkali chloroborate glasses have been studied in the ultraviolet-visible near-infrared regions. Various spectroscopic parameters like Racah (E¹, E², and E³), spin orbit (ξ_4f), and configuration interaction (α) parameters have been calculated. From the measured spectral intensities of the various absorption bands of Ho³⁺ ion, the Judd–Ofelt intensity parameters (Ω₂, Ω₄, and Ω₆) have been evaluated and covalency was studied as a function of x in the glass matrices. Using these parameters, radiative transition probabilities, radiative lifetimes, branching ratios, and integrated absorption cross-sections have been calculated and reported for certain excited states of Ho³⁺ ion. From the emission spectra, stimulated emission cross-sections are determined for the emission transitions, ⁵F₄, ⁵S₂?→?⁵I₈, and ⁵F₅?→?⁵I₈ in these two mixed alkali chloroborate glasses. An attempt has been made to throw some light on the environment of Ho³⁺ ions in these glass systems by studying the variation in various spectroscopic parameters.     

Optical absorption and emission properties of Nd in TeO2-WO3 and TeO2-WO3-CdO glasses

Effects of WO₃ and CdO on the spectroscopic properties of Nd³⁺ doped tellurite glasses were investigated. The optical band gaps and Urbach energies of the samples were determined using the dependence of the absorption coefficient on the photon energy. The Urbach energies were found to vary from 0.18 to 0.25 eV as the WO₃ content in the binary glasses decreased from 20.0 to 10.0 mol% while the optical band gap of the same glasses did not show an appreciable dependence on the glass composition. Judd-Ofelt (Ω_t) parameters were calculated from the optical absorption spectra measured at room temperature. In all the glasses the J-O parameters follow the same trend as Ω₂>Ω₆>Ω₄. The J-O intensity parameters were used to compute the radiative properties such as the radiative transition probabilities (A_ed), branching ratios (β) and radiative lifetimes (τ_r) for all the possible fluorescence bands. The fluorescence spectra obtained upon 805.2 nm excitation exhibited an intense emission band centered at 1064 nm (⁴F_3/2→⁴I_11/2) and two weak bands at 910 nm (⁴F_3/2→⁴I_9/2), and 1340 nm (⁴F_3/2→⁴I_13/2). The stimulated emission cross-section for the 1064 nm emission was determined using the emission spectra. The highest gain bandwidth (σ_e×Δλ_P) was determined to be 155.4 for the 0.79TeO₂-0.15WO₃-0.05CdO ternary glass composition, which could be more useful as promising material for the design and development of fiber amplifiers and lasers.     

Optical and luminescence properties of Dy3+ ions in K–Sr–Al phosphate glasses for yellow laser applications

Trivalent dysprosium (Dy³⁺)-doped K–Sr–Al phosphate glasses have been prepared and investigated for their optical and luminescence properties. Judd–Ofelt theory has been used to derive radiative properties for the ⁴F_9/2 level of Dy³⁺ ions. The luminescence spectrum of 1.0 mol% Dy₂O₃-doped glass shows intense yellow emission around 572 nm ascribed to ⁴F_9/2 → ⁶H_13/2 transition with 78 % branching ratio and emission cross section of the order of 2.48 × 10^?21 cm². Moreover, the quantum efficiency of the ⁴F_9/2 level has been found to be 76 %. The luminescence decay curves for the yellow emission (⁴F_9/2 → ⁶H_13/2) have been measured and analyzed as a function of Dy³⁺ ion concentration. The results revealed that Dy³⁺-doped phosphate glasses could be useful for yellow laser applications.     

Optical properties of Pr3+-doped SrWO4 crystal

The polarized absorption and emission spectra of Pr³⁺ ions in SrWO₄ single crystals were investigated at room temperature. The standard and modified Judd–Ofelt theories have been applied to analyze the polarized absorption spectra to determine the spectroscopic parameters, including the Judd–Ofelt intensity parameters Ω_t (t=2,4,6), radiative transition probabilities, radiative lifetimes and branching ratios. The stimulated emission cross sections and fluorescence lifetimes of the promising laser level were obtained. PACS 78.55.Hx; 42.70.Hj; 78.20.-e