Integrated Emission Cross Sections Research Articles

High quantum efficiency of 1.8 μm luminescence in Tm3+ fluoride tellurite glass

In this paper, Tm3+ doped fluorotellurite glasses are synthesized by melt-quenching technique. The thermal and spectral properties of the glasses are characterized. The effect of the 1.8 μm emission properties for different Tm3+ concentrations are investigated. ΔT (153 ℃) of the glass indicates it has good thermal stability. Spectroscopic parameters of Tm3+ such as radiative transition probability, branching ratio, spectroscopic quality factor, integrated emission cross section and radiative lifetime are calculated on the basis of Judd-Ofelt analysis. The maximum half-height width corresponding to 1.8 µm broadens as Tm3+ increases and reaches a maximum of 216 nm, as well as the longer lifetime (5.68 ms). For 1.8 µm (3F4 → 3H6) emission band, the calculated Tm3+ doped fluorotellurite glass has a high quantum efficiency of 75.93%. Furthermore, the theoretical analysis of the energy transfer mechanism between Tm3+ ions were represented. Therefore, these results demonstrate that prepared Tm3+ doped fluorotellurite glass is an ideal laser material for 1.8 µm band solid-state laser applications.

Spectroscopic studies of K2GdF5:Nd3+ single crystals for incredibly strong NIR emission at 864 nm

K2GdF5 single crystals doped with 5.0 at.% of Nd3+ ions (K2GdF5:Nd3+) were synthesized by the hydrothermal technique. The identification and control of the phase purity of synthesized crystals were performed using powder X-ray diffraction analysis. The spectroscopic characteristics of Nd3+ ions in K2GdF5 were analyzed through the absorption and luminescence spectra as well as decay curves. Upconversion luminescence spectra of K2GdF5:Nd3+ in the visible region were recorded under excitation by laser radiation with a wavelength of 785 nm. The nature of the Nd3+- ligand bonding and Judd-Ofelt intensity parameters were estimated using the absorption spectrum. The Ω4/Ω6 ratio was used to predict the structure of the emission spectrum of the K2GdF5:Nd3+ crystal. The application capability of the 4F3/2 → 4I9/2 emission band (864 nm) for laser action in K2GdF5:Nd3+ is proposed based on the radiative parameters such as the experimental branching ratio (βexp), integrated emission cross-section (ΣJJ’) and stimulated emission cross-sections (σλp). The nonradiative energy transfer process between Nd3+ ions in K2GdF5:Nd3+ is also discussed in detail using the Inokuti-Hirayama and Yokota-Tamimoto models.

Influence of BaX2 (X = Cl, F) and Er2O3 concentration on the physical and optical properties of barium borate glasses

Er3+ ions doped oxyhalide barium borate glasses were prepared by means of conventional melt quenching technique. In the studied glass system, besides the Er3+ doping, barium oxide was partially replaced by BaF2 and/or BaCl2. The amorphous nature of as-prepared glasses was confirmed by X-ray diffraction patterns. The effects of the compositional changes were investigated through spectroscopic techniques such as optical absorption, emission and decay lifetime. It was found that the luminescence and decay lifetime of Er3+: 4I13/2 → 4I15/2 transition are affected by both Er3+ doping and halide insertions. By applying the Judd-Ofelt (JO) theory, the JO intensity parameters (Ωt, t = 2, 4, and 6) were calculated, and the trend Ω2 > Ω4 > Ω6 was found, which is in accordance with previous studies. Optical properties such as electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were also obtained and discussed for many excited states of Er3+ ions. The lifetime of the 4I13/2 excited level was measured and compared with the calculated one.

Thermal stability and spectroscopic study of Ho3+/Yb3+ co-doped fluorophosphates glasses

Holmium/Ytterbium co-doped fluorophosphate glasses with compositions (80-x-y) NaPO3-10SrF2-10ZnF2- xHoF3- yYbF3 (x = 1 and y = 0.5, 1, 1.5 and 2 mol%) were prepared by melt-quenching technique. The stability criteria indicate that these glasses exhibit a good resistance against devitrification. Densities of glasses were determined and showed an almost linear variation with increase of YbF3 content. Spectroscopic parameters of Ho3+ such as radiative transition probability, branching ratio, spectroscopic quality factor, integrated emission cross section and radiative lifetime, were calculated on the basis of Judd-Ofelt analysis. The results showed that these glasses could be proposed as suitable lasing materials.

Energy transfer phenomena and Judd-Ofelt analysis on Sm3+ ions in K2GdF5 crystal

The Raman, absorption, luminescence spectra and lifetimes curves of Sm3+-doped K2GdF5were measured. Based on the Judd-Ofelt analysis, the values of radiative transition probabilities, branching ratios, integrated emission cross-sections and radiative lifetimes of excited states of Sm3+ in K2GdF5 crystal were calculated. The migration of excitation energy between the Gd3+ ions and the trapping processes of Gd3+ excitation energy by Sm3+ and Tb3+ions in K2GdF5 crystal are reported. The role of the overlapping between the broad, allowed absorption bands of the RE3+ ions and the narrow absorption lines 6IJ and 6PJ of Gd3+ ions on the trapping rates of the RE3+ was discussed. The energy transfer between the Sm3+ ions was studied by the decay measurement, which has been fitted by Inokuti-Hirayama energy transfer model and revealed that electric dipole–quadrupole interaction is responsible for the energy transfer process in Sm3+ ions doped K2GdF5 crystal.

Concentration effects on the optical spectroscopic properties of Er3+- doped TeO2–Nb2O5–ZnO vitreous system

A detailed spectroscopic study of erbium doped tellurite glasses having the basic molar composition (70TeO2 -10Nb2O5-20ZnO) and containing different concentrations of Er2O3 (x=0.5, 1.5, 2.5, 3.5) (in wt %) is presented in this work. These glasses were prepared according to the conventional melt-quenching method. Using optical absorption data and Judd–Ofelt theory, several spectroscopic parameters such as optical band gap energy, Urbach energy, transition probabilities (AJ-J′), radiative lifetimes (τrad), branching ratios (β) and integrated emission cross-sections (σem) for the different 4f-transitions were estimated for different Er2O3 contents. Photoluminescence spectroscopy measurements were performed for the different samples at room temperature using 488 nm excitation wavelength of an argon-ion laser. The influence of Er2O3 concentration on the lifetime of 4I13/2 level and line shape of the infrared emission at 1532 nm was analyzed using Mc Cumber theory and the observed results were correlated with the glass structure. Our results were compared to those existing in recent literature for others TeO2 based glasses. It was found that the effective bandwidth is larger and the optical gain coefficient and the quality factor are higher than those obtained for others vitreous systems, which suggests that the proposed glasses can be nominated as suitable host material for new Er3+doped broad-band optical amplifiers and the developments of optical devices.

Optical Transition Probabilities of Er3+Ions in ErBa3B9O18Crystal

The optical absorption and emission intensity of luminescent and birefringent crystal ErBa3B9O18were examined from optical absorption data based on Judd-Ofelt theory. The three intensity parametersΩt(t=2,4,6) are 3.10 × 10−20, 0.87 × 10−20, and 1.80 × 10−20 cm2, respectively. From the obtained intensity parameters, the radiative probabilitiesAr, radiative lifetimeτf, fluorescence branching ratiosβc, and integrated emission cross sections∑have been calculated. In comparison with other Er-doped luminescent crystals, ErBa3B9O18may find application in thin disk laser.

Spectroscopic investigation and Judd–Ofelt analysis of silver nanoparticles embedded Er3+-doped tellurite glass

A series of silver nanoparticles (NPs) embedded zinc-tellurite glass is prepared by melt-quenching technique. The transmission electron microscopic images reveal spherical as well as anisotropic silver NPs having average diameter in the range of 14–48 nm. The Er3+-free glass sample containing AgCl exhibits surface plasmon resonance (SPR) band of Ag NPs centered at ∼ 501 nm. From Judd–Ofelt analysis, it is found that by increasing the concentration of NPs, the value of Ω2 is enhanced suggesting increased covalency and decreased symmetry around the Er3+ ions. Integrated emission cross-section (IEC) is enhanced as the concentration of silver NPs is increased up to 0.5 mol% AgCl. Fourier infrared spectra show that the intensity of the vibrational band of the water molecule and fundamental stretching band of OH group are suppressed. Furthermore, under an excitation wavelength of 786 nm, three prominent upconversion emissions are observed at 520 nm, 550 nm and 650 nm which are attributed to 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 transitions, respectively. The upconversion emissions are enhanced significantly by introduction of silver NPs. The enhancement is mainly attributed to the local field effect of silver NPs. Studied nanocomposites are potential candidates for the development of solid state lasers.

Fluorescence and Judd-Ofelt Analysis of Er<sup>3+</sup> Doped CaF<sub>2</sub> Transparent Ceramic

In this paper, we evaluated the spectra parameters of Er3+.The absorption spectra of Er3+:CaF2transparent ceramic was measured at room temperature (RT). Based on the Judd–Ofelt theory, the intensity parameters were Ω2= 5.02×10−20cm2, Ω4= 3.40×10−20cm2and Ω6= 0.38×10−20cm2, and then the values of the radiative transition probabilities, radiative lifetimes and integrated emission cross-sections of excited states were calculated. Full width at half maximum (FWHM) of the fluorescence spectra for4I13/2→4I15/2transition was investigated, being 17nm. The decay time was found to be 24.3ms, which is longer than the theoretically calculated value indicating a radiation trapping effect in this work.

Optical properties and Judd–Ofelt parameters of Dy3+ doped K2GdF5 single crystal

Dy3+-doped K2GdF5 single crystals with 10.0mol% have been prepared by hydrothermal condition. The spectra are analyzed in term of the Judd–Ofelt theory, the intensity parameters (Ωλ, λ=2, 4, 6) have been evaluated for Dy3+-doped K2GdF5 sample. The electric (Sed), magnetic (Smd) dipole line strength, radiative (A), and total radiative (AT) transition probabilities, lifetime (τR), branching ratios (βR) for the excited levels of Dy3+ doped K2GdF5 crystals were investigated by using the intensity parameters. In addition, the stimulated emission cross-sections (σλp) and integrated emission cross-section (Σif) have been predicted for the transitions from excited level, 4F9/2, to the 6H15/2, 6H13/2 and 6H11/2 levels. The energy transfer occurs from Gd3+ to Dy3+, resulting in the additional intense excitation UV-narrow bands for the luminescence of the Dy3+ ions.

Spectroscopic study and green upconversion of Pr3+/Yb3+-codoped NaY(WO4)2 crystal

The absorption spectra of Pr3+/Yb3+-codoped NaY(WO4)2 crystal has been measured at room temperature. Based on the Judd–Ofelt theory, the intensity parameters Ωt (t=2, 4, 6), spontaneous transition probabilities, integrated emission cross sections and radiative lifetimes were calculated. Upconversion (UC) emissions of the sample had been recorded under an excitation from a 975nm laser diode, and intense green UC emissions were observed. The energy transfer mechanisms responsible for the population of 3PJ (J=0, 1, 2) level were analyzed.

Growth and optical properties of Nd:LaVO4 monoclinic crystal

Abstract

Optical properties of Dy3+ ions in La3Ga5SiO14 crystal

AbstractThe absorption and fluorescence spectra of Dy3+‐doped La3Ga5SiO14 (LGS) crystals were measured and analyzed according to the Judd–Ofelt theory. When applied, the following spectral parameters have been obtained: phenomenological intensity parameters Ωt, Ω2 = 2.64 × 10−20 cm2, Ω4 = 1.39 × 10−20 cm2 and Ω6 = 0.63 × 10−20 cm2. These intensity parameters were used to predict radiative properties that included electronic line strengths, radiative transition probabilities AJ″,J′, the radiative lifetime τrad, the fluorescence branching ratios βJ″,J′. The value of absorption section σabs(λ), and the integrated emission cross sections σem(λ) were also calculated. The emission transition 4F9/2 → 6H13/2 provides potential applications of LGS:Dy crystal as a laser material.

Spectral Properties and Parameters Calculation of Er:Ligdf<sub>4</sub> Crystal

The absorption and fluorescence spectra of Er3+:LiGdF4 crystal was measured at room temperature. Base on the Judd-Ofelt theory, the intensity parameters of Er3+ in LiGdF4 crystal were determined, Ω2=0.905×10-20cm2, Ω4=2.47×10-20cm2 and Ω6=4.92×10-20cm2. The values of the radiative transition probabilities, branching ratios, integrated emission cross-section and radiative lifetimes of excited states of Er3+ in LiGdF4 crystal were calculated. The stimulated emission cross-section was also evaluated for the 4I13/2→4I15/2 transitions. In comparisons with other Er3+ doped laser crystals, Er3+:LiGdF4 crystal has potential as a promising laser crystal.

Optical-transition properties of the Nd 3+ ion in KLu(WO 4) 2 crystal

Optical absorption and emission intensities of Nd 3+ ion in KLu(WO 4) 2 crystal were investigated. Based on the Judd-Offelt theory, we calculated the following spectral parameters: phenomenological intensity parameters Ω 2=5.567×10 −20, Ω 4=3.597×10 −20, and Ω 6= 3.800×10 −20 cm 2. The radiative lifetime of levels 4F 3/2 was 182.58 μs. The fluorescence branching ratio for the transition 4F 3/2→ 4I 11/2 was 46.98%. In addition, the radiative transition probabilities A J,J', oscillator strengths P J,J' and the values of integrated emission cross sections were also calculated. In comparison with those of other laser crystals, these results indicated that Nd: KLuW is a promising efficient laser material.

Optical properties and up-conversion of Pr 3+ doped CdS nanoparticles in sol–gel glasses

Silica glasses containing Pr 3+ with and without CdS nanoparticles were prepared by sol–gel technique. The influence of CdS nanoparticles on Pr 3+ doped glass was studied by absorption, photoluminescence and up-conversion. From the measured intensities of various absorption bands of these glasses, the Judd–Ofelt parameters Ω 2, Ω 4 and Ω 6 have been evaluated. The radiative transition probability ( A), radiative lifetime ( τ R ), branching ratio ( β R ) and integrated emission cross-section ( σ P ) were calculated from excited states of 3P 1 and 3P 0 levels. The up-conversion emissions were found in the green, orange and red regions under 800 nm excitation with peaks 559, 612 and 688 nm respectively. On excitation with 370 nm also leads to similar green, orange and red regions.

Growth and optical properties of Pr 3+:La 2CaB 10O 19 crystal

Pr 3+ doped La 2CaB 10O 19 crystal were grown by the top-seeded solution growth (TSSG) method. The absorption spectra, emission spectra and lifetime were measured at room temperature. The J-O parameters (Ω t , t=2,4,6), the radiative transition probabilities A J, J' , oscillator strengths P J, J' , radiative lifetime τ, fluorescence branch ratios β J and the value of integrated emission cross section have also been calculated. Five main absorption bands, 3H 4 to 3P 1+ 3P 2, 3P 0, 1D 2, 3F 3 + 3F 4 and 3F 2, were observed in the absorption spectra. The 1G 4 absorption band was not observed. A very strong emission band at 601 nm ( 1D 2 → 3H 4) was observed in the emission spectra. The experimental lifetime for this level was compared with that obtained theoretically by using J-O approach.

Enhanced electronic transition probabilities and line intensities of Er + 3 ion in a (W, La)-tellurite glass as revealed from Judd–Ofelt analysis

A series of tellurite glasses containing dispersed Er 2WO 6 nanocrystals of different concentration was prepared, and the optical properties of the best luminescent sample (1 g mol% of Er 2O 3) were investigated by Judd–Ofelt theory. The intensity parameters Ω 2 ( = 8.410 × 1 0 − 20 cm 2 ) , Ω 4 ( = 4.833 × 1 0 − 20 cm 2 ) , Ω 6 ( = 2.027 × 1 0 − 20 cm 2 ) of the Er +3 ion in the glass were determined and then used to calculate parameters such as the radiative transition probabilities ( A r ), radiative life-times ( τ f ), fluorescence branching ratios ( β c ) and the integrated emission cross-section ( Σ σ ) of different transitions. The experimental optical constant and the calculated oscillator strength values ( P ) suggest that the Er +3 ions in the glass can most effectively be excited by 4 I 15 / 2 → 4 F 7 / 2 (489 nm) and 4 I 15 / 2 → 2 H 11 / 2 (522 nm), 4 I 15 / 2 → 4 F 9 / 2 (653 nm) and 4 I 15 / 2 → 4 I 13 / 2 (1533 nm) transitions while the spontaneous emission rate ( A r ) values show that strong visible emissions should occur respectively through ( 4 F 9 / 2 → 4 I 15 / 2 ) and ( 4 S 3 / 2 → 4 I 15 / 2 ) transitions and strong NIR emissions through ( 4 I 13 / 2 → 4 I 15 / 2 ), ( 4 S 3 / 2 → 4 I 11 / 2 ), ( 4 F 9 / 2 → 4 I 13 / 2 ), ( 4 I 11 / 2 → 4 I 15 / 2 ), ( 4 S 3 / 2 → 4 I 13 / 2 ) transitions. The spectroscopic parameters show that the glass is a superior photonic material compared to other known Er +3 doped glass and crystals.

Judd–Oflet analysis of spectrum and laser performance of Ho:YAP crystal end-pumped by 1.91-μm Tm:YLF laser

The Ho:YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho:YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd–Ofelt intensity parameters Ω2 = 1.42 × 10−20 cm2, Ω4 = 2.92 × 10−20 cm2, and Ω6 = 1.71 × 10−20 cm2, this paper calculated the fluorescence lifetime to be 6 ms for 5 I7 →5 I8 transition, and the integrated emission cross section to be 2.24 × 10−18 cm2. It investigates the room-temperature Ho:YAP laser end-pumped by a 1.91-μm Tm:YLF laser. The maximum output power was 4.1 W when the incident 1.91-μm pump power was 14.4W. The slope efficiency is 40.8%, corresponding to an optical-to-optical conversion efficiency of 28.4%. The Ho:YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8 nm.

Optical parameters and energy levels splitting of Ho3+ in Ho3+: GdVO4

Ho3+ : GdVO4 is a new laser material suitable for high-power laser systems. In this paper we measure the absorption spectra of Ho3+ in the sample Ho3+: GdVO4. The intensity parameters are calculated by using the Judd–Ofelt theory. Some predicted spectroscopic parameters, such as the spontaneous radiative transition rate, branching ratio and integrated emission cross section are dealt with. And we also compare the optical parameters with those of other materials. From these results, it is found that there are many transitions which have large oscillator strengths and large integrated emission cross sections. Especially the transitions such as 5F4 → 5 I8, 5S2 → 5 I8,5F5 → 5 I8 and 5I7 →5 I8 are useful in solid-state lasers and other fields. Finally, we discuss the splitting of the energy levels of Ho3+ in the crystal GdVO4 based on the group theory.