Spectroscopic characteristics of Pr<Superscript>3+</Superscript> in biaxial La<Subscript>2</Subscript>(WO<Subscript>4</Subscript>)<Subscript>3</Subscript> crystal

A Pr³⁺-doped La₂(WO₄)₃ crystal grown by the Czochralski method has been investigated as a promising laser material. The principal axes of the optical indicatrix and Pr³⁺ concentration of the crystal were determined. The polarized absorption, fluorescence spectra and fluorescence decay curves of the main emission multiplets of the crystal were measured at room temperature. The spectroscopic parameters were obtained by the modified Judd–Ofelt theory combined with the normalized method. The peak stimulated emission cross-sections of the major emission lines were estimated. The good spectroscopic properties imply that the Pr³⁺:La₂(WO₄)₃ crystal is a potential laser gain medium for solid-state laser and self-stimulated Raman laser applications. PACS 78.20.-e; 42.70.Hj     

Optic characteristics of Pr3+ doped NaY(MoO4)2 crystal

The polarized absorption and emission spectra of Pr³⁺ ions in NaY(MoO₄)₂ single crystal were investigated. The standard and modified Judd–Ofelt theory have been applied to the measured optical absorption intensities to determine the spectroscopic parameters, including the Judd–Oflet intensity parameters Ω_t (t=2,4,6), the radiative transition rates, branching ratios, and emission cross-sections for various excited levels of Pr³⁺ ions. In samples with Pr³⁺ ions concentration of 2.00×10²⁰ cm^-3, the excitation of the ¹ D ₂ manifold decays non-radiatively by the electric dipole–dipole transfer between Pr³⁺ neighbors. The good spectroscopic properties show the possible application of the Pr³⁺ doped NaY(MoO₄)₂ crystal as a solid-state laser. PACS 42.70.Hj; 78.20.-e     

Spectroscopic properties of Pr 3+ 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 _t(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. PACS 78.20.-e; 42.70.Hj     

Spectroscopic analysis of Pr3+:CaYAlO4 crystal

The polarized absorption, emission spectra and decay time measurements of Pr³⁺-doped CaYAlO₄ single crystal have been performed at room temperature. Based on the Judd–Ofelt theory, the spectroscopic parameters \(\Upomega_{t} (t = 2,4,6)\) , radiative transition probabilities, radiative lifetimes and branching ratios were obtained. The stimulated emission cross-section, fluorescence lifetimes and the quantum efficiency of the promising laser transition were also calculated and compared with other reported crystals. The results show that Pr³⁺:CaYAlO₄ is a promising candidate for visible solid-state laser emission.     

Growth, spectroscopic characteristics and laser potential of Yb3+:Ca3La2(BO3)4 crystal

Crystal of Yb³⁺-doped Ca₃La₂(BO₃)₄ has been grown by the Czochralski technique. The room temperature absorption and fluorescence spectra of the crystal have been investigated. The result showed that this crystal exhibits broad absorption and emission with the FWHM of 11 nm at 978 nm and 66 nm FWHM at 1025 nm, respectively. The stimulated emission cross-section of Yb³⁺ ions were calculated using the reciprocity method and Fuchtbauer-Ladenburg method, respectively. The room temperature fluorescence decay curves of ² F _5/2 manifold of Yb³⁺ ions were recorded for both crystal and powder samples. The effect of radiation tapping on the spectroscopic properties is discussed. The result that the lifetime of the powder sample is shorter than that of the bulk sample demonstrates the existence of radiation trapping effect. The laser potentiality was also evaluated and the results show that this crystal is a good candidate for tunable and ultrashort pulse lasers.     

Pr<Superscript>3+</Superscript>-doped Tl<Subscript>3</Subscript>PbBr<Subscript>5</Subscript>: a non-hygroscopic,non-linear and low-energy phonon single crystal for the mid-infrared laser application

This letter presents the optical and spectroscopic properties of a new low-energy phonon, moisture-resistant and non-linear Pr³⁺:Tl₃PbBr₅ single crystal. Though only weakly doped with Pr³⁺ ions, centimetre-size and good-quality single crystals could be grown and analyzed. Absorption and emission spectra as well as fluorescence kinetics were registered in the mid-infrared spectral domain. Strong luminescence at around 4–5.5 μm was observed and assigned to the ³H₅→³H₄ transition of the Pr³⁺ ions. The high value of the resulting emission cross section associated with the long lifetime of the ³H₅ emitting level indicates that this material could be a good candidate for the development of a broadly tunable mid-infrared solid-state laser source.     

Up-conversion multiwave (White) luminescence in the visible spectral range under excitation by IR laser diodes in the active BaY2F8:Yb3+,Pr3+ medium

The possibilities of occupying high-lying 4f states of Pr³⁺ ions in the active BaY₂F₈:Yb³⁺,Pr³⁺ medium according to the photon avalanche and step-by-step sensitization mechanisms are compared. It is shown that the photon avalanche is unlikely to occur in the BaY₂F₈:Yb³⁺,Pr³⁺ crystal. The multiband luminescence spectra in the visible spectral range (white emission) under single- and multiwave pumping of BaY₂F₈:Yb³⁺,Pr³⁺ crystal by IR laser diodes are reported.     

The laser-diode-excited 5d-4f luminescence of Ce3+ and Pr3+ ions embedded into a BaR2F8 matrix

We show the possibility of obtaining UV luminescence from 5d-4f transitions of rare-earth ions in the BaY₂F₈: (Yb³⁺, Pr³⁺, Ce³⁺) crystal under upconversion excitation by standard laser diodes with lasing wavelengths of 960, 808, and 840 nm. Various upconversion mechanisms of pumping for populating the higher-lying energy levels of the active ions, as well as methods of adaptation of the active medium BaY₂F₈: (Yb³⁺, Pr³⁺, Ce³⁺) to these mechanisms, are considered.     

Polarized spectral analysis of Er3+ ions in biaxial Bi2(MoO4)3 crystal

An Er³⁺:Bi₂(MoO₄)₃ single crystal has been grown by the Czochralski technique. The Stark sublevels of the ⁴I_15/2 and ⁴I_13/2 multiplets of Er³⁺ ions in the crystal were determined. The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curve of the crystal were measured at room temperature and the relevant spectroscopic parameters, including the Judd–Ofelt intensity parameters, spontaneous emission probability, fluorescence branching ratio, radiative lifetime, and stimulated emission cross section, were estimated. The effect of re-absorption on the spectroscopic parameters was discussed. When the crystal was excited at 977 nm, up-conversion green fluorescence was observed and discussed.     

Absorption and fluorescence intensity analysis of Pr3+ in LiPrP4O12 crystal

Absorption and fluorescence spectra of LiPrP₄O₁₂ crystal were measured with high accuracy. Using the Judd-Ofelt theory the Ω_λ parameters and probabilities of the radiative transitions for the ³P₀, ¹D₂, excited states were calculated. From the presented analysis of the fluorescence spectra of Pr³⁺ ions, we conclude that there are two unequivalent positions in LiPrP₄O₁₂ crystals.     

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     

On spectroscopic properties of the KYb(WO4)2:Pr3+ crystal

Spectroscopic properties of Pr³⁺ doped KYb(WO₄)₂ single crystals were investigated. The crystal lattice parameters were determined. Energy levels of Pr³⁺ in KYb(WO₄)₂ were assigned. The absorption, emission, excitation, time-resolved emission and excitation spectra were measured at low (10 K) and at room temperature. Decay times of the praseodymium emissions are non-exponential and unusually short. Site selection spectroscopy evidences several different Pr³⁺ sites. The Judd-Ofelt intensity model was used to analyse the experimental data. The Ω λ parameters, branching ratio and electric dipole transition probabilities were determined.     

Spectroscopic properties of Yb ions in La2(WO4)3 crystal

Yb³⁺-doped La₂(WO₄)₃ single crystals were grown by the Czochralski technique. Absorption and fluorescence spectra of the crystal were recorded at the room temperature. The stimulated emission cross-sections of Yb³⁺ ions were calculated using the reciprocity method and Fuchtbauer-Ladenburg formula, respectively. The fluorescence decay curves of ²F_5/2 manifold of Yb³⁺ ions were recorded at room temperature for both crystal and powder samples. The effect of radiation trapping on the spectroscopic properties is discussed. Comparison with other Yb³⁺-doped laser crystals is made. The results show that Yb³⁺:La₂(WO₄)₃ crystal is a promising laser material.     

Spectroscopic properties of Pr:KY(MoO4)2 crystal as a visible laser gain medium

A Pr³⁺-doped KY(MoO₄)₂ single crystal was grown by the Czochralski method. The polarized absorption and fluorescence spectra of the Pr³⁺:KY(MoO₄)₂ crystal were measured at room temperature. The stimulated emission cross-sections for the transitions from the ³P₀ multiplet were estimated from the fluorescence spectra. The fluorescence lifetime of the ³P₀ multiplet was estimated from the fluorescence decay curve at room temperature. The analysis of spectral properties shows that the Pr³⁺:KY(MoO₄)₂ crystal is a promising gain medium for visible lasers.     

Affinement d'une raie de fluorescence de Pr3+: LaAlO3 par excitation laser

A cw dye laser has been used for fluorescence line narrowing experiments by resonant excitation on Pr³⁺ ions in LaAlO₃. Scanning the excitation radiation through the absorption line width corresponding to the transition ³H₄ (0 cm^-1) → ¹D₂ (16 694 cm^-1) while fluorescence was observed, has put into evidence a deformation of the symmetry around Pr³⁺ ions, different for every site.This experiment shows the power of cw dye laser spectroscopy for investigating optical spectra in crystals.     

Pr3+在SBN晶体中的发光特性

通过测量Ｐｒ：ＳＢＮ晶体的吸收光谱和荧光光谱来确定Ｐｒ³⁺在ＳＢＮ晶体中的能级位置。由于Ｐｒ³⁺离子占据晶体中的不同格位而引起荧光带呈现双峰结构。测量荧光寿命随温度的变化关系，表明Ｐｒ³⁺在ＳＢＮ晶体中 ³Ｐ₀态的无辐射弛豫主要是 ³Ｐ₀→¹Ｄ₂多声子弛豫过程。 关键词：     

Absorption and emission spectra of yttria-stabilized zirconia and magnesium oxide

We have investigated the luminescence and absorption spectra of doped and undoped ZrO₂-Y₂O₃ and MgO crystals at room- and low temperatures. The crystals used are partly doped with the transition metals Ni, Co, Cr and the rare earth Pr. The emission spectra were obtained under laser excitation at different wavelengths. The observed optical emission and absorption bands of the MgO crystals doped with Ni, Co and Cr correspond to transitions between spin-orbit split crystal field levels of the transition metals. Luminescence and absorption bands of undoped yttria-stabilized zirconia (YSZ) crystals are due to color centers, absorption bands of the doped YSZ correspond to the well known transitions of the Ni²⁺, Co²⁺ and Pr³⁺ ions, respectively. The emission spectra of the doped YSZ obtained under various laser excitations can be explained by an energy transfer process between the color center and the doping materials. The influence of annealing on the absorption and emission of Pr³⁺/Pr⁴⁺ is investigated.     

Pr3+/Ho3+共掺Ge-Ga-Se玻璃的2.9 μm荧光特性的研究

采用熔融冷却法制备了系列Ho³⁺/Pr³⁺共掺的Ge₂₅Ga₁₀Se₆₅玻璃样品,测试了样品的吸收光谱以及908 nm激光抽运下的中红外荧光光谱和Ho³⁺离子⁵I₇能级寿命.计算了Ho³⁺:⁵I₇→⁵I₈发射截面和Pr³⁺:³H₄→³F₂吸收截面,讨论了Ho³⁺,Pr³⁺离子之间的能量转移效率及Pr³⁺离子浓度的影响.通过拟合Ho³⁺离子2.0 μm荧光衰减曲线判断能量转移机理.结果表明,Ho³⁺掺杂Ge₂₅Ga₁₀Se₆₅玻璃中引入Pr³⁺离子可以有效提高Ho³⁺离子的2.9 μm荧光强度. 关键词： 中红外发光 硫系玻璃 3+/Pr³⁺共掺')" href="#">Ho³⁺/Pr³⁺共掺     

Luminescent properties of trivalent praseodymium-doped lanthanum aluminum germanate LaAlGe2O7

The luminescent characteristics of Pr³⁺-activated LaAlGe₂O₇ were investigated. In response to excitement using 448 nm blue light, the emission spectra involved most of the ³P₀→³H_J transitions. The dominant emission came from the ³P₀→³H₄ transition at 487 nm. ¹D₂ fluorescence quenching was observed in highly doped samples and is related to the cross-relaxation processes among neighboring Pr³⁺ ions. In contrast with conventional Pr³⁺-activated phosphors, the extraordinary excitation spectra showed only intense f-f transition of Pr³⁺ ions, while the 4f-5d transition was eliminated. This is ascribed to photoionization. By analyzing absorption and excitation spectra, it is recognized that no efficient energy transfer occurs between Pr³⁺ and the host lattice in LaAlGe₂O₇.