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The crystal of ZnWO4 doped with Co2+ has been grown by the Czochralski technique. The orientation procedure was presented. Along the crystallographic axes, the principal coefficients of thermal expansion and absorption spectra were measured and discussed. Based on the data, the crystal field parameter 10Dq, Racah parameter B, as well as the absorption cross sections were calculated. The nonlinear dependence of optical absorption on concentration of cobalt ions was found and discussed in single crystal Co2+:ZnWO4. The results indicate that inner defects such as natural cleavage or slip faces in crystal are important in the study of optical and thermal properties. [ABSTRACT FROM AUTHOR]

Er3+:SrWO4 crystal of good optical quality was grown by Czochralski technique method. Polarized absorption and emission spectra of Er3+ ions in SrWO4 crystal have been investigated. The Judd-Ofelt (JO) theory was applied to the polarized absorption spectra of Er3+:SrWO4 to obtain the three JO parameters: Ω2=7.41×10-20 cm2, Ω4=0.25×10-20 cm2, and Ω6=1.71×10-20 cm2. The radiative probabilities, radiative lifetimes, and branch ratios of Er3+:SrWO4 were calculated. The stimulated emission cross sections of the potential laser transitions at 1535 nm were determined using the reciprocity method and the Fuchtbauer-Ladenberg formula, and the potential laser gain versus wavelength for the 4I13/2→4I15/2 transition has been estimated and discussed. [ABSTRACT FROM AUTHOR]

Abstract: The polarized absorption and emission spectra have been measured for the Tm3+ doped NaY(MoO4)2 crystal and spectral parameters have been estimated from the absorption data based on the Judd–Ofelt theory. The effective intensity parameters (t =2, 4, 6) are 11.67×10−20, 2.21×10−20, 1.74×10−20 cm2, respectively. From the intensity parameters, the radiative transition probabilities, radiative lifetimes, branching ratios and the emission cross-section have been calculated. In comparison with other Tm3+ doped laser crystals, Tm3+:NaY(MoO4)2 crystal has potential as a promising laser crystal. [Copyright &y& Elsevier]

Abstract: Large crystals of pure and Y b3+ doped NaY (MoO4)2 have been grown using the Czochralski method. The major problem with these crystals is that they are black in colour, causeing total absorption in the visible range, this was resolved by annealing and the nature of the colour defect was discussed. Measurements such as DTA, thermal expansion in different crystallographic directions, and refractive index as a function of wavelength were investigated. The broad absorption band at about 980 nm and high value of the absorption cross-section are obtained for the Y b3+ doped crystal. The results show that Y b3+:NaY (MoO4)2 crystal has potential as a promising laser crystal. [Copyright &y& Elsevier]

Abstract: The Dy3+-doped NaY(MoO4)2 single crystals were grown successfully by the Czochralski technique. The main spectroscopic properties (absorption, luminescence, decay curve) of Dy3+-doped NaY(MoO4)2 have been determined for both the σ and π polarizations. By using the Judd–Ofelt theory, the measured room temperature absorption spectra were applied to determine the intensity parameters, spontaneous transition probabilities, branching ratios, and radiative lifetimes of Dy3+ transitions. The results show that the Dy3+-doped NaY(MoO4)2 crystal may realize the yellow laser operation. [Copyright &y& Elsevier]

Abstract: Tm doped NaBi(WO4)2 of good optical quality with sizes of about 20mm×20mm×40mm was grown successfully by the Czochralski technique. The absorption spectra for both σ- and π-polarizations were recorded at room temperature. Based upon these data, the oscillator strengths and radiative transition rates were evaluated. The σ- and π-polarized emission spectra together with the fluorescence decay curve were also obtained. The emission cross-section of the potential laser transition at 1460nm was determined to be 1.49×10−19 cm2. The results show that Tm3+:NaBi(WO4)2 crystal is a promising laser material. [Copyright &y& Elsevier]

Abstract: The polarized absorption, emission spectra and the fluorescence decay curve of Er3+ ions in the anisotropic NaY(MoO4)2 crystal were investigated at room temperature, and spectral parameters have been calculated from the absorption data based on the Judd–Ofelt theory. The experimental oscillator strengths for the transitions from the ground state to excited states were compared with the theoretical oscillator strengths calculated from the Judd–Ofelt theory. The emission cross-section and gain cross-section for the π- and σ-spectrum were determined for the 4H13/2 → 4H15/2 transition of special interest for laser application. [Copyright &y& Elsevier]

Abstract: Dy3+: Ca3(BO3)2 crystal was grown successfully by the Czochraski technique. The absorption spectrum was measured and its absorption peaks were assigned. The Judd–Ofelt intensity parameters were found to be Ω 2=5.216×10−20, Ω 4=1.858×10−20, Ω 6=0.623×10−20 cm2. The spectroscopic parameters of this crystal such as the oscillator strengths, radiative transition probabilities, radiative lifetime as well as the branching ratios were calculated. Also, room temperature luminescence decay curve in correspondence with the emission line 4F9/2→6H13/2 centered at 575nm was measured. [Copyright &y& Elsevier]

Abstract: Large novel birefringent pure and rare earth-doped calcium borate crystals (Ca3(BO3)2) have been grown successfully by Czochralski technique. Thermal expansion coefficients of pure Ca3(BO3)2 have been obtained for the first time. Trivalent rare earth ions (RE3+), such as Dy3+- and Nd3+-doped calcium borate crystal, have been grown for optic application. Absorption and fluorescence spectra as well as fluorescence decay curves of Dy3+-, Nd3+-doped Ca3(BO3)2 crystals are measured at room temperature. Optical spectra show that there are obvious absorptions at ultraviolet to IR region. The strong emissions in visible and infrared region show that calcium borate is a suitable for rare earth-doped laser crystal. [Copyright &y& Elsevier]

Abstract: The single crystal of ZnWO4:Ho3+ was grown by Czochralski technique. The XRD, absorption spectra, fluorescence spectrum are presented, and the Judd–Ofelt (J–O) intensity parameters Ω 2, Ω 4, Ω 6 are obtained to be 4.61×10−20 cm2, 0.16×10−20 cm2, 0.48×10−20 cm2, respectively. Calculated radiative transition rate, branching ratios, and radiative lifetime for different transition levels of ZnWO4:Ho3+crystals are presented. The most intense line correlative with the transition 5S2 → 5I8 at 543nm is potentially used for green solid state laser, and the fluorescence lifetime of this energy level is 14.1μs. [Copyright &y& Elsevier]

Abstract: Good quality crystals ZnWO4 activated with Er3+ have been grown by means of Czochralski method and characterized using optical spectroscopy techniques. XRD, absorption spectra, fluorescence spectrum are presented and the Judd–Ofelt intensity parameters Ω 2, Ω 4, and Ω 6 are obtained to be 6.76×10–20, 0.37×10–20, and 0.50×10–20 cm2, respectively. Along crystallographic axes, refractive indices are presented. The fluorescence decay time of the 4 I 13/2 level has also been investigated and shows an exponential behavior with a lifetime value of 5.52ms. The crystal is potentially used for green and infrared eye-safe lasers. [Copyright &y& Elsevier]

Abstract: Dy3+-doped NaGd(WO4)2 crystal with sizes of about Φ20×40mm2 was grown by the Czochralski technique along the (001) 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 4F9/2 level was determined to be approximately 63% for this material. The emission cross-section of the 4F9/2→6H13/2 transition was estimated by using the Füchtbauer–Ladengurg method. [Copyright &y& Elsevier]

Abstract: Nd3+-doped NaLa(WO4)2 single crystal with a dimension of ∅20mm×40mm and a good optical quality was grown by Czochralski method. The polarized absorption spectra and emission spectra were measured at room temperature. The absorption cross-section and emission cross-section were presented. The Judd–Ofelt theory, extended to anisotropic system, has been applied to evaluate the intensity parameters Ω t (t =2,4,6), radiative transition rates A, radiative lifetimes τ R and fluorescent branching ratios β. The calculated radiative lifetime was compared with the experiment data for the 4F3/2 emitting level. All spectral features are strongly affected by an inhomogeneous broadening connected with the ‘disordered crystal’ character of the title compound. [Copyright &y& Elsevier]

Abstract: Holmium doped sodium gadolinium tungstate crystals with sizes of about Ø20mm×40mm were grown successfully by the Czochralski technique along the (001) orientation. Polarized absorption spectra, fluorescence spectra and fluorescence decay curve of Ho3+-doped NaGd(WO4)2 have been recorded at room temperature. Based on the Judd–Ofelt theory, three intensity parameters were obtained. The spectroscopic parameters of this crystal such as the oscillator strengths, radiative transition probabilities, radiative lifetimes as well as the branching ratios were calculated. The fluorescence lifetime τ f of the 5S2 level was measured to be 5μs. [Copyright &y& Elsevier]

Abstract: crystal with the size up to 13 mm×44 mm was grown successfully by the Czochralski technique and its optical properties were presented. The absorption cross-section and emission cross-section were presented. Also, the potential laser gain near 1.9 μm was investigated. In the framework of the Judd–Ofelt (J–O) theory, the intensity parameters were calculated to be: Ω2=11.375×10−20 cm2, Ω4=5.077×10−20 cm2 and Ω6=6.524×10−20 cm2. The spectroscopic parameters of this crystal such as the oscillator strengths, radiative transition probabilities, radiative lifetime as well as the branching ratios were calculated, too. This crystal is promising as a tunable infrared laser crystal. [Copyright &y& Elsevier]

Abstract: This paper reports the growth of Nd3+:NY(WO4)2 crystal with high optical quality and large size. Nd3+:NY(WO4)2 crystal with the dimension Φ30×75mm2 and optical homogeneity 4×10−5 was grown by Czhchoralski method: the seed used was [100] orientation, the pulling rate and rotating rate were 0.5–1.25mm/h and 15rpm, respectively. The growing processes and characteristics of Nd3+:NY(WO4)2 crystal was discussed. Its unpolarized absorption spectra and emission spectra were measured. The absorption cross-section and emission cross-section were presented. Based on the Judd–Ofelt theory, we obtained the three intensity parameters: , , and . The radiative probabilities, radiative lifetimes, branch ratios and quantum efficiency of Nd3+:NY(WO4)2 were calculated too. [Copyright &y& Elsevier]