Modified Judd Ofelt Theories Research Articles

Standard and modified Judd-Ofelt theories in Pr3+-doped calcium aluminosilicate glasses: A comparative analysis

The small energy difference between the fundamental level and the first opposite parity configuration of Pr3+-doped hosts is particularly challenging for the characterization of radiative transitions using the Judd-Ofelt theory, although modified versions of the theory have been proposed in the past for the investigation of praseodymium doped materials. Here, we present a detailed spectroscopic investigation on two sets of calcium aluminosilicate glasses, with 34 wt% of SiO2 (CAS) and with 7 wt% of SiO2 (LSCAS), doped with different concentrations of Pr3+ (0.5, 1.0 and 2.0 wt%). We use the standard Judd-Ofelt theory to characterize the glasses and the results and derived spectroscopic quantities — such as transition probabilities, radiative lifetimes and branching ratios — are compared to results obtained by the modified Judd-Ofelt theories. The analysis showed that the modified theories could lead to smaller values of root mean square deviations. However, a better agreement between experimental data and the standard theory was achieved when the derived spectroscopic quantities are taken into account. Moreover, the branching ratios of the P03→H43 and D21→H43 transitions were over 60% for both glass hosts, suggesting its potential use as solid-state laser devices.

Application of modified Judd–Ofelt theory and the evaluation of radiative properties of Pr3 +-doped lead telluroborate glasses for laser applications

Praseodymium doped lead telluroborate (PTBPr) glasses were prepared by conventional melt quenching method. The absorption spectra have been analyzed to evaluate the intensity parameters applying the standard and the modified Judd–Ofelt theories. The emission spectra under 3P2 level excitation (λex=447nm) were investigated to estimate the laser characteristic parameters. These emission measurements together with Judd–Ofelt intensity parameters (Ωλ=2,4,6) have been used to calculate the radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of the transitions from 3P0 and 1D2 levels to their lower lying levels. The quenching of fluorescence intensity and experimental lifetime with the increase of Pr3+ concentration and the shift of 1D2→3H4 emission peak towards longer wavelengths was discussed. The non-radiative losses due to multiphonon and energy transfer relaxations were also explained. The Commission Internationale de I'Eclairage (CIE) coordinates, color purity and optical band gap energy values were evaluated. Some of the basic laser characteristics such as stimulated emission cross-section, optical and bandwidth gain parameters and fluorescence quantum efficiency were also reported.

Spectroscopic analysis of Pr 3+:Gd 3Ga 5O 12 crystal as visible laser material

Pr 3+-doped Gd 3Ga 5O 12 single crystal is potentially good for generations of new lasers at visible range. The absorption and emission spectra of this crystal were measured at room temperature, as well as its fluorescence decay curves. Standard and modified Judd–Ofelt theories were used to analyze its intensity parameters, and the fluorescence properties for the 3P 0 emitting multiplet were predicted. To characterize the existence of the 3P 0 → 3F 3 and 3P 0 → 3H 5 transitions, which violate the selection rules of electric dipole transition, we also introduced the experimental branching ratio to reflect practical portion of transitions from 3P 0 multiplet. The stimulated emission cross sections of the promising laser transitions were then calculated and compared with other crystals which had realized efficient visible laser emissions. By analysing the spectroscopic properties we have showed that the Pr:GGG is an excellent candidate for solid state laser materials.

Spectroscopic properties of Pr 3+:SrMoO 4 crystal

A Pr 3+-doped SrMoO 4 single crystal has been grown successfully by the Czochralski technique. The absorption spectra, fluorescence spectra, and fluorescence decay curves have been measured at room temperature. The spectroscopic parameters, including spectroscopic parameters Ω t ( t = 2,4,6), radiative transition probabilities, radiative lifetimes and branching ratios were determined according to the standard and modified Judd–Ofelt theories. The stimulated emission cross-sections, the fluorescence lifetimes and the quantum efficiency of Pr 3+ ions in SrMoO 4 were obtained. This study implies that Pr 3+:SrMoO 4 is an attractive candidate for solid-state laser medium.

Characteristic of the 1S 0 level in Pr 3+:ZBLAN glass by two-step excitation

We experimentally report on the energy position, branching ratios, lifetimes and emission cross sections of the 1S 0 level in Pr 3+:ZBLAN glasses by two-step excitation process: 3H 4 → 1D 2 → 4f5d. The calculated branching ratios and lifetimes of 1S 0 by the standard as well as the modified Judd-Ofelt theories are compared with the measured ones. The results by the modified Judd-Ofelt theory, which more reasonably takes into account the effects of the configuration energies on the 5d perturbations to the 4f levels, have better agreements with the experimental results. The 1S 0 luminescence by another two-step excitation process 3H 4 → 3P 0 → 4f5d is also discussed.

Spectroscopic properties of Pr 3+:Gd 3Ga 5O 12 crystal

The room-temperature absorption spectrum, fluorescence spectra, and fluorescence decay curves of Pr 3+-doped Gd 3Ga 5O 12 single crystal were studied systematically. The standard and modified Judd–Ofelt theories were used to determine 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 the fluorescence quantum efficiency of the promising laser levels were calculated and discussed. The multi-exponential behavior of the fluorescence decay curve of the 1D 2 → 3H 4 transition was explained by using the Inokuti–Hirayama theory. The obtained spectroscopic results show the potential application of the Pr 3+-doped Gd 3Ga 5O 12 crystal as visible solid-state lasers.

Calculating line intensities of 1S0 emission through standard and modified Judd–Ofelt theories inPr3+-dopedCaAl12O19 andSrAl12O19

A modified Judd–Ofelt theory is used in this paper to treat the electric dipole transitions within the4f2 configurationof Pr3+ by considering two main perturbing components of 4f5d and4fn′g. Through the energy-level calculation and standard tensorialanalysis, the explicit distance between the 4f5d configuration and the 1S0 state andother lower 4f2 energy levels are determined. The rare-earth ionPr3+ substitutedat Sr2+ sites inSrAl12O19 (SAO) andCa2+ sites inCaAl12O19 (CAO) has the sitesymmetry of D3h. The standardJudd–Ofelt parameters A332, A334,A534,A536,A736 are included in the calculation, together with odd-λ parametersA333 andA535. The emitting line intensities originating from 1S0 and3P0 are then calculated. Compared with the experimental measurements, the modified modelyields better results than the standard Judd–Ofelt theory.

Growth and spectroscopic properties of Pr3+ doped Sr3Y2(BO3)4 crystal

Pr3+ doped Sr3Y2(BO3)4 single crystal has been grown by the Czochralski method. The spectroscopic properties of Pr3+:Sr3Y2(BO3)4 crystal have been investigated based on the absorption spectra, fluorescence spectra and fluorescence decay curves which are recorded at room temperature. The standard and modified Judd–Ofelt theories, extended to anisotropic crystals, have been applied in analysis of the spectra. The spectroscopic parameters, including the Judd–Ofelt intensity parameters, spontaneous transition probabilities, fluorescence branching ratios, radiative lifetimes and fluorescence quantum efficiencies, are calculated and analysed.

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 Ωt (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.

Spectroscopic properties of Pr3+ ions in NaGd(WO4)2 crystal

A Pr3+-doped NaGd(WO4)2 single crystal has been grown by the Czochralski technique along the (0 0 1) orientation. The refractive indices were measured precisely as a function of wavelength. A Raman spectrum, polarized absorption spectra, fluorescence spectra, and fluorescence decay curve have been recorded at room temperature. The standard and modified Judd-Ofelt theories have been performed to analyze the absorption spectra to determine the spectroscopic parameters, including the Judd-Ofelt intensity parameters Ωt (t=2,4,6), radiative transition probabilities, radiative lifetimes, and branching ratios. The stimulated emission cross sections and fluorescence lifetime of the promising laser level were obtained.

Spectroscopy and laser properties of Tm3+:KY(WO4)2 crystal

The polarized absorption spectra of Tm3+-doped potassium yttrium tungstate (Tm:KY(WO4)2) crystal at room temperature were measured. The emission spectrum and lifetime of the 3F4 excited state were determined. Using standard and modified Judd–Ofelt theories, the intensity parameters and the radiative lifetimes were calculated and good agreement with the experimental results was obtained for both theories. Continuous-wave laser operation in Tm:KYW crystal under laser diode pumping at 802 nm and 1750 nm was demonstrated with slope efficiency of 53% and 28% and output power of about 555 mW and 86 mW, respectively.

Application of original and modified Judd–Ofelt theories to the 1S 0 state of Pr 3+-doped SrAl 12O 19 and LaF 3

The main fluorescence branching ratios of 1S 0 state in SrAl 12O 19:Pr 3+and LaF 3:Pr 3+ have been determined by vacuum ultraviolet excitation. The original and modified Judd–Ofelt analyses both with normalized method were applied to the absorption spectra of Pr 3+ to get three phenomenological intensity parameters: Ω 2, Ω 4, and Ω 6. They were subsequently employed to calculate the branching ratios and decay times of the Pr 3+ 1S 0 level in SrAl 12O 19 and LaF 3. The result showed that in both hosts, the modified Judd–Ofelt theory with normalized method provided a better agreement with experimental data than the original one.

Spectroscopic properties of Pr3+ ions in biaxial LaB3O6 crystal

La B 3 O 6 single crystal doped with Pr3+ ions has been grown by the Czochralski method. The angular relationship between the principal axes of the optical indicatrix and the crystallographic axes in the crystal was determined. The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curves of the crystal were measured at room temperature. The modified Judd-Ofelt theories, extended to the anisotropic crystal, have been applied to analyze the spectra. The spectroscopic parameters, including the Judd-Ofelt intensity parameters Ωt,q(t=2,4,6), spontaneous emission probabilities, fluorescence branching ratios, radiative lifetimes, fluorescence quantum efficiencies, and stimulated emission cross sections were calculated and analyzed. The promising luminescent and upper laser level of the Pr3+:LaB3O6 crystal is determined.

Spectroscopic properties of Pr3+ in anisotropic PbWO4 crystal

The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curves of Pr3+ ions in anisotropic PbWO4 single crystal, which was grown by the modified Bridgman method, were measured at room temperature. The standard and modified Judd–Ofelt theories, extended to anisotropic crystal, have been applied to analyze the spectra. The spectroscopic parameters, including the Judd–Ofelt intensity parameters Ωt (t=2,4,6), spontaneous emission probabilities, fluorescence branching ratios, radiative lifetimes, stimulated emission cross sections, and fluorescence quantum efficiencies, were estimated. The good spectroscopic properties show the possible application of the Pr3+-doped PbWO4 crystal as solid-state and self-stimulated Raman laser materials.

Optical intensities of Pr3+ ions in transparent oxyfluoride glass and glass–ceramic. Applications of the standard and modified Judd–Ofelt theories

The optical characterisation of Pr3+ ions in transparent SiO2–Al2O3–CdF2–PbF2–YF3 based glass and glass–ceramic have been performed. From absorption and emission spectra the oscillator strengths of the 4f2–4f2 electronic transitions have been obtained. The intensity parameters have been calculated using both the Judd–Ofelt theory and the modified theory developed by Kornienko, Kaminskii and Dunina. A comparison of the experimental oscillator strengths, the spontaneous emission probabilities and the lifetimes of the 3P0 level and those calculated using the above theoretical procedures has been performed for both samples. The root mean square deviation found using the standard Judd–Ofelt theory is larger than the value obtained with the modified treatment.

Application of standard and modified Judd–Ofelt theories to thulium doped fluoroindate glass

Fluoroindate glasses of the following compositions: (40– x)InF 3–20ZnF 2–16BaF 2–20SrF 2–2GdF 3–2NaF– xTmF 3 with x=1,3 mol% were prepared in a dry box under an argon atmosphere. The absorption spectra at room temperature in the spectral range 350–2200 nm were obtained. The spectra obtained for each sample had similar absorption and only the amplitude of the different bands changed as the concentration of Tm 3+. The experimental oscillator strengths were determined from the areas under the absorption bands. Using the standard and modified Judd–Ofelt theory, intensity parameters Ω λ ( λ=2,4,6) and ( λ=2,3,4,5,6), respectively for f–f transitions of Tm 3+ ions as well as transition probabilities, branching ratios and radiative lifetimes for each band were determined. The results are compared with those of other glasses described in the literature.

Comparison Between Standard and Modified Judd-Ofelt Theories in a Pr3+-Doped Fluoride Glass

Α method which takes into account normalized oscillator strengths is detailed for the calculation of parameters in Judd-Ofelt theory (B.R. Judd, Phys. Rev. 127, 750 (1962), G.S. Ofelt, J. Chem. Phys. 37, 511 (1962)). In the case of a Pr3+ -dopaed fluorozirconate glass, the Judd-Ofelt parameters obtained in this way do not depend strongly on the transitions included in the frt. Particularly, it is no longer necessary to exclude the 3H4 → 3Ρ2 transition from tle analysis. Three modifred theories (F. Auzel, S. Hubert, P. Delamoye, J. Lumin. 26, 251 (1982), A.A. Kornienko, A.A. Kaminskii, E.B. Dunina, Phys. Status Solidi B 157, 267 (1990)) are also considered but do not improve the calculated intensities when the energy of the 5d level is set to its experimentally determined value. Finally, in connection with 1.3 μm amplification, the 1.3 hn1 reabsorption ( 1i.4 → 1D2) oscillator strength is computed from the various models as well as the 1.3 /im emission branching ratio ( 1G4 --> 3H5/ 1G4 — 3H6). The best agreement with experiment is obtained with the standard Judd-Ofelt theory.

Application of standard and modified Judd–Ofelt theories to a praseodymium-doped fluorozirconate glass

A method which takes into account normalized oscillator strengths is detailed for the calculation of parameters in Judd–Ofelt theory (B. R. Judd, Phys. Rev. 127, 750 (1962), G. S. Ofelt, J. Chem. Phys. 37, 511 (1962)). In the case of a Pr3+-doped fluorozirconate glass, the Judd–Ofelt parameters obtained in this way do not depend strongly on the transitions included in the fit. Particularly, it is no longer necessary to exclude the 3H4→3P2 transition from the analysis. Two modified theories [F. Auzel, S. Hubert, and P. Delamoye, J. Lumin. 26, 251 (1982), and A. A. Kornienko, A. A. Kaminskii, and E. B. Dunina, Phys. Stat. Solidi. 157, 267 (1990)] are also considered but do not improve the calculated intensities when the energy of the 5d level is set to its experimentally determined value. Finally, in connection with 1.3 μ amplification, the 1.3 μ reabsorption (1G4→1D2) oscillator strength is computed from the various models as well as the 1.3 μ emission branching ratio (1G4→3H5/1G4→3H6). The best agreement with experiment is obtained with the standard Judd–Ofelt theory.