Yb2O3 Concentration Research Articles

Highly efficient up-conversion green emission in Ho/Yb co-doped yttria-stabilized zirconia single crystals

In the development of materials with valuable luminescence properties, we have used the optical floating zone method to prepare single crystals in the cubic phase of yttria-stabilized zirconia (YSZ) doped with 0.75 mol% Ho2O3 and various concentrations of Yb2O3. The influence of Yb3+ contents was determined for absorption and photoluminescence spectra, and fluorescence decay curves at room temperature. The absorption spectra consisted of several peaks that could be assigned to various transitions involving Yb3+ and Ho3+ ions, and oscillator strength parameters Ωt (t = 2, 4, 6) were determined using the Judd-Ofelt theory, along with the transition probability, lifetime, and branching ratio from the absorption and emission spectra of the crystal of YSZ co-doped with 0.75 mol% Ho2O3 and 1.5 mol% Yb2O3. The Ω2 value of ~14 × 10–20 cm2 indicates that the bonding around Ho3+ involves lower symmetry and higher covalency than in several other hosts, and the value of the ratio Ω4/Ω6 of 1.93 shows that this sample is a good candidate material for high quality laser output. Up-conversion emission spectra showed that Yb3+ doping significantly increased the emission intensity of 0.75 mol% Ho2O3 doped YSZ at green (557 nm), red (670 nm) and NIR (758 nm) wavelengths when excited by a 980 nm laser, and reached a maximum for 1.5 mol% Yb2O3. The emission at 557 nm was much sharper than that reported for nanocrystals of similar composition, where the maximum intensity was observed at 540 nm. Down-conversion PL spectra showed two prominent emission peaks at 1040 nm and 1213 nm, and the fluorescence decay curves indicate that energy transfer between Yb3+ and Ho3+ influenced the lifetime of the excited state of Ho3+ which varied with Yb2O3 concentration. Overall these results indicate that these Yb/Ho co-doped YSZ crystals have considerable potential for laser and luminescence applications.

Step-index high-absorption Yb-doped large-mode-area fiber with Ge-doped raised cladding.

We report an all-solid large-mode-area (LMA) step-index fiber offering high absorption and low core numerical aperture (NA) by introducing a highly ytterbium-doped P:Al core and germanium-doped cladding. The fiber provides core absorption of ∼1200 dB/m at 976nm with a low 0.07 core NA, due to the raised Ge cladding. Furthermore, matched profiles of P and Al across the core are successfully obtained with high concentration of Yb2O3 around 0.4mol%. The fiber characteristics are routinely achievable by conventional modified chemical vapor deposition with a solution doping technique. A highly efficient laser with >100 W output power, 86% slope efficiency with respect to launched pump power, and a mean M2 of 1.34 has been demonstrated using the fabricated LMA step-index fiber. We also report 80% laser slope efficiency with 58W output power (pump power limited) within only 0.5m of the fiber when pumped by a wavelength-stabilized laser diode.

Sensitizing effect of Yb3+ ions on photoluminescence properties of Er3+ ions in lead phosphate glasses: Optical fiber amplifiers

The Er3+/Yb3+-codoped lead phosphate (PPbKANErYb) glasses have been prepared by using melt quenching technique and characterized through spectroscopic studies such as absorption, emission, decay and upconversion measurements. An intense near-infrared (NIR) emission at 1.53 μm was observed which has been explained based on the effective energy transfer from Yb3+ to Er3+ ions. The absorption (4I15/2 → 4I13/2) and emission cross-section (4I13/2 → 4I15/2) of 1.53 μm emission band was calculated and found to be of the order of 6.76 × 10−21 and 7.9 × 10−21cm2, respectively, by using the McCumber theory. The PPbKANErYb glasses exhibit higher luminescence intensity (more than 3 times) and full width at half maxima (55 nm) compared to 1.0 mol % Er3+ singly doped glass (50 nm). All the decay curves of the 4I13/2 level exhibited single exponential nature and the lifetimes increased (1760, 1776, 1942 and 2830 μs) with the increase of Yb2O3 (0.5, 1.0, 2.0 and 3.0 mol %) concentration. Intense red band at 670 nm corresponding to 4F9/2 → 4I15/2 transition and green emission bands at around 530 and 555 nm corresponding to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2, transitions, respectively, have been observed under the excitation of 980 nm. The intensity of the upconversion emissions is found to be increased with the increase of Yb3+ ion concentration and its mechanism have been explained. The luminescence decay curves of the 4S3/2 → 4I15/2 upconversion luminescence of Er3+/Yb3+ codoped PPbKAN glasses under the infrared excitation of 980 nm have been evaluated. The results reveal that the investigated glasses might be potential candidates for optical fiber amplifiers/laser sources at 1.55 μm band.

30/900 Yb-doped Aluminophosphosilicate Fiber Presenting 6.85-kW Laser Output Pumped With Commercial 976-nm Laser Diodes

To incorporate sufficient pumping power, a large-scale Yb-doped aluminophosphosilicate (Al2O3 -P2O5-SiO2, APS) fiber with 30- μ m core and 900- μ m inner clad in diameter, i.e., a 30/900 Yb-APS fiber, was theoretically designed and experimentally fabricated by using modified chemical vapor deposition system combining with chelate precursor doping technique. Analyzed by an electron probe microanalyzer, the dopant concentration of Yb2O3, Al2O 3, and P2O5 was estimated to be 0.14 mol%, 1.1 mol%, and 1.4 mol%, respectively. Based on an all-fiberized master oscillator power-amplifier laser setup directly forward pumped by commercial 976-nm laser diodes, 6.85-kW laser output at 1079.79 nm was achieved with an optical-to-optical efficiency of 67.1%, and the beam factor of $M^{2}$ was 2.38. The results indicate that large-scale Yb-APS fiber is quite competitive for high-power fiber laser development.

Composition dependence of the adjustable microstructure and mechanical properties of ytterbia-ceria-costabilised TZP

A series of (YbO1.5)x(CeO2)0.12−2x(ZrO2)0.88+x compounds with adjustable microstructure and mechanical properties were prepared by a conventional solid state reaction method. The evolution of phase composition, microstructure and mechanical properties with the variation of composition were investigated. All (YbO1.5)x(CeO2)0.12−2x(ZrO2)0.88+x ceramics were composed of single tetragonal phase. With the increase of Yb2O3 doping content, the lattice parameters and tetragonality decrease continuously, meanwhile, the microstructure of all samples became more homogeneous and much refiner. Moreover, with increasing Yb2O3 concentration, the Vickers hardness increased from 6.99 to 14.02 GPa and the bending strength ranged from 425.19 to 1136.25 MPa constantly, while the fracture toughness decreased gradually from 14.7 to 5.72 MPa m1/2. The adjustable microstructure and mechanical properties of this system can meet different demands of practical applications.

Structural and spectroscopic properties of Yb3 +-doped zinc aluminate nanocrystals in silicate glass-ceramics

In this work, effect of the Yb2O3 doping on the structure and spectroscopic properties of zinc aluminate nanocrystals formed in the glasses were investigated. Zinc aluminate nanocrystals were precipitated in the glasses through heat-treatment. X-ray diffraction, transmission electron microscopy and absorption spectroscopy were utilized to characterize the structural and spectroscopic properties. It was found that pure ZnAl2O4 spinel nanocrystals were formed in the glasses without Yb2O3 doping. As the doping concentration of Yb2O3 increased, Yb3+ ions were incorporated into the zinc aluminate nanocrystals and gradually changed the structure of space group of zinc aluminate from Fd3−m to F432. Both elemental mapping and absorption spectroscopy confirmed the incorporation of Yb3+ ions into the nanocrystals formed in the glasses.

Bright blue cooperative upconversion emission of Yb3+ from langbeinite K2Ti1.887 Yb0.113(PO4)3 single crystal

Ytterbium doped langbeinite K2Ti1.887Yb0.113(PO4)3 (KTYP) single crystals were grown using high temperature molten salt flux growth method. Inclusion-free KTYP crystals with sizes up to 3×3×3mm3 were attained using K6P4O13 molten flux. The complete melting point of solute and solvent is above at 1223K. Langbeinite phase KTYP crystals are growing in higher concentration of Yb2O3 in flux solution. KTYP emits a strong cooperative blue emission centered at 488nm owing to Yb-Yb pairs under 980nm laser excitation. To the best of our knowledge, phosphate based langbeinite crystal found exhibit cooperative upconversion emission at ~488nm.

Microstructure and Dielectric Behavior of Ytterbium Doped BaZr0.1Ti0.9O3 Ceramics

BaZr0.1Ti0.9O3 ceramics of perovskite structure are prepared by solid state reaction method with addition of x Yb2O3 (x= 0.0, 0.1, 0.3, 0.5 and 0.7 mol%), respectively, and their dielectric properties are investigated. Room temperature X-ray diffraction study suggested that the compositions have a single phase with a perovskite structure. A small decrease in the grain size is observed with an increase in the Yb content. The bulk density increased with increasing the Yb content for the samples sintered at 1250 0C, and the bulk densities show the maximal value for the samples sintered at 1280 0C, 1300 0C and 1330 0C. The dielectric constant can reach to 4500 or more for the sample sintered at 1300 0C, and the variation of dielectric loss with temperature is more stable for Yb2O3-doped BZT10 ceramics, which proves that Yb2O3 doping has a great influence on the dielectric properties in BZT10 ceramics. With the increase of Yb2O3 content, Tc rises at first, and when x exceeds 0.1 mol%, Tc shifts towards to lower temperature with the Yb2O3 concentration increasing.

Luminescence and energy transfer progress in Bi-Yb co-doped germanate glass

The Bi-doped and Bi-Yb co-doped germanate glasses were fabricated by high temperature melting-quenched technique. The absorption spectra, near-infrared (NIR) luminescence properties and decay time spectra are investigated. The results show that the NIR emission peak around 1030 nm of Yb3+ ions and two NIR emission bands around 1180 and 1300 nm of Bi ions are observed, under 690 nm LD excitation. Two NIR emission bands of Bi-related are ascribing in different Bi-related NIR emission centers, Bi0 for 1180 nm and Bi+ ion for 1300 nm, respectively. NIR luminescence intensity of Yb3+ ions, Bi0 and Bi+ ion is decreased. The full width at half maximum (FWHM) is broadening with the increasing in Yb2O3 concentration, and over 361 nm. The energy transfer (ET) among Yb3+, Bi0, and Bi+ NIR emission center is also investigated, under 690 nm LD excitation. It shows that Bi0 ion transfer energy to Bi+ and Yb3+ ions. The Yb3+ ion addition is benefit to Bi+ ions NIR luminescence. This could be the reason for broadening the FWHM. Yb–Bi codoped germanate glass is a promising material for broadband optical amplification.

Effect of concentration of Sm2O3 and Yb2O3 and synthesizing temperature on electrical and crystal structure of (Bi2O3)1−x−y(Sm2O3)x(Yb2O3)y electrolytes fabricated for IT-SOFCs

For intermediate temperature solid oxide fuel cells (IT-SOFCs), (Bi2O3)1−x−y(Sm2O3)x(Yb2O3)y ternary systems (x=0.01 and y= 0.11), (x=0.05 and y= 0.07), (x=0.07 and y=0.05), and (x=0.11 and y=0.01) as electrolytes have been fabricated at different temperatures (700, 750, and 800°C) by solid state ceramic technique (SST). The characterization of the samples has been performed by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), four point-probe method (FPPM), X-ray energy diffraction spectroscopy (EDX), and differential thermal analysis (DTA). XRD measurements have shown that only the samples (Bi2O3)1-x-y(Sm2O3)x(Yb2O3)y (x=0.01, y=0.11 synthesized at 700, 750, and 800°C) and (x=0.05, y=0.07 synthesized at 800°C) have stable fluorite type face centered cubic (FCC) δ-phase. SEM images have shown the morphology of the stable samples. The conductivity and the operation temperature region of the samples have been determined from Arrhenius curves obtained from the FPPM measurements data and they vary from 1.83 to 9.95×10−1Scm−1. Moreover, activation energy of the samples have been calculated by means of Arrhenius curves of the samples and relationships between them and the conductivity of the samples have been investigated in detail. The results obtained from XRD and FPPM measurements were confirmed by the DTA measurements.

Spectroscopy and radiation trapping of Yb3+ ions in lead phosphate glasses

This paper reports ytterbium-doped lead phosphate (PbPhYb) glasses made by melt-quenching technique and their linear and nonlinear refractive indices. Raman and FTIR spectral analysis has been carried out to investigate the functional groups that constitute the host matrix. The oscillator strength of the absorption transition, (2F7/2→2F5/2) has been evaluated by using the Smakula model for various concentrations. The near infra-red emission and excitation spectra have been investigated and observed that the profile of the emission spectra changes as a function of Yb2O3 concentration, temperature, optical path length and thickness of the sample. From the optical absorption spectra, the spectroscopic and laser performance parameters have been evaluated and in turn used to estimate the gain cross-section of the Yb3+ ions. On the other hand, the lifetime for the 2F5/2 level of Yb3+ ion decreases with increase in Yb2O3 concentration up to 6mol% after an initial increase due to energy migration among the Yb3+ ions. The increase in lifetime could be due to radiation trapping but when the concentration is enlarged the energy migration processes are more predominant. The emission profile and lifetime change when the temperature is reduced to cryogenic temperature (11K). The results reveal that the prepared glasses could be considered for high energy and high power laser as well as solid state cryocooler applications.

Fabrication and XAFS analysis of Yb3+ doped yttrium lanthanum oxide transparent ceramics

(YbxY0.90−xLa0.10)2O3 (x=0.01–0.10) transparent ceramics were fabricated and their structural properties were investigated. The XRD showed our samples exhibited single cubic Y2O3 phase. The lattice parameters were refined with the Rietveld method. The compact structure and an average grain size of 40–50μm were revealed by the microstructure. The local fine structure around Yb ions was investigated by using the XAFS (X-ray absorption fine structure) technique. The results showed that: the local structure around Yb ions in the samples with different concentration of Yb ions was basically similar, and Yb ions replaced Y position to form the solid solution. The Yb ions were trivalent. With the concentration of Yb2O3 increased, the coordination number (N) and first shell Yb–O bond length (R) decreased, and the degree of disorder (σ) increased.

Properties Investigation of Yb<sup>3+</sup>-Doped Phosphate Glasses for Fiber Laser

The physical and optical properties of P2O5-Al2O3-ZnO glasses doped with different concentration of Yb3+ions were investigated. The experimental results indicated that density, chemical durability, glass transition temperature (Tg) and glass softening temperature (Td) of glasses increase with increasing the Yb2O3content of glasses. However, the coefficient of thermal expansion (α) for glasses decrease with increasing the Yb2O3content. From the results of Fourier transform infrared spectroscopy, the numbers of (-P-O-P-) bonds decrease and (-P-O-M+-) bonds increase with increasing the Yb2O3content. Increase of non-bridge oxygen (-P-O-M+-) raise the refractive index of glasses. Moreover, the results of absorption spectra indicate that the absorption peak of glasses are observed at both wavelengths of 916nm and 977nm. As increasing the concentration of Yb2O3, the absorption efficiencies become stronger. In accordance with the results of fluorescence spectra, the fluorescence emission of glasses are detected at wavelengths of 970nm, 995nm, 1020nm and 1048nm, respectively. The intensity of the fluorescence emission peaks significantly decrease at wavelengths of 970nm and 995nm as the concentration of Yb2O3increases. However, the intensity of the fluorescence emission peaks significantly increase at wavelength of 1048nm under the same condition.

Spectroscopic studies and downconversion luminescence in OH−-free Pr3+–Yb3+ co-doped low-silica calcium aluminosilicate glasses

We report on spectroscopic studies and downconversion luminescence in OH−-free Pr3+–Yb3+ co-doped low-silica calcium aluminosilicate glasses (LSCAS). The dependencies of the visible to near-infrared emissions, photoacoustic signals, luminescence decay times and energy transfer efficiencies from Pr3+→Yb3+ on the doped Yb2O3 concentration were investigated. The results confirmed the occurrence of downconversion processes in the examined samples, followed by a back-energy transfer mechanism from the Yb3+:2F5/2 level to the Pr3+:1G4 level, from where the multiphonon relaxations through the 1G4,3F4→3H4 transitions occurred. The photoacoustic data provided evidence of the energy transfer that resulted in heat generation in the sample, confirming the observations provided by the luminescence data. The energy transfer mechanisms that are involved in the Pr3+:Yb3+ co-doped LSCAS glasses are discussed.

Effects of Yb2O3 on the NIR emission performance of Bi–Yb codoped aluminophosphsilicate glasses

Glasses with the composition 37.5SiO2–12.5P2O5–25Al2O3–25PbO–0.5Bi2O3–xYb2O3 (x=0–1mol%) were prepared and characterized. When excited by 690 and 808nm, broadband near infrared emissions of Bi ions centered at 1150 and 1300nm, respectively, as well as the transition of Yb3+: 2F5/2→2F7/2 could be observed simultaneously, and the emission intensity of Yb3+ was enhanced with increasing of Yb2O3 concentration. Energy transfer processes between Bi emitting centers and Yb3+ were discussed according to the effects of Yb2O3 addition on the near infrared emissions from Bi ions.

Optical properties of Yb3+ ions in fluorophosphate glasses for 1.0 μm solid-state infrared lasers

Yb3+-doped fluorophosphate glasses were prepared by melt-quenching technique and characterized their spectroscopic properties to assess the laser performance parameters. The magnitude of absorption (emission) cross-sections at 975 nm for all the studied Yb3+-doped glasses is found to be in the range of 0.29–1.50 × 10−20 (0.59–1.99 × 10−20 cm2) which is much higher than those of commercial Kigre QX/Yb: 1.06 × 10−20 (0.5 × 10−20 cm2) laser glass. The luminescence lifetimes of 2F5/2 level decrease (1.15–0.45 ms) with increase in Yb2O3 concentration (0.1–4.0 mol%). Effect of OH− content on luminescence properties of Yb3+ ions has also been investigated. The effect of radiative trapping has been discussed by using McCumber (McC) and Fuchtbauer–Ladenburge (F–L) methods. The product of experimental lifetimes and emission cross-sections for 0.1 mol% Yb2O3-doped glass is found to be 2.28 × 10−20 cm2 ms which indicates that the higher energy storage and extraction capability could be possible. The detailed spectroscopic results suggest that the studied glasses can be considered for high-power and ultrashort pulse laser applications.

Near-infrared downconversion in Pr^3+/Yb^3+ co-doped boro-aluminosilicate glasses and LaBO_3 glass ceramics

We report on downconversion of one blue photon to two near-infrared (NIR) photons (~10000 cm−1) in Pr3+/Yb3+ co-doped SrO-La2O3-Al2O3-B2O3-SiO2 glasses and LaBO3 glass ceramics. The Pr3+ ions act as broadband spectral sensitizer in the spectral range of 415-505 nm. Energy transfer occurs subsequently from Pr3+ to Yb3+, followed by re-emission in the NIR spectral range. The transfer efficiency is indicated by the degree of decrease of Pr3+-related photoluminescence (PL) and PL lifetime of the 3P0 and 1D2 levels with increasing Yb3+ concentration. For the present case, we find an optimum dopant concentration of Yb2O3 of ~0.5 mol % for a Pr2O3 concentration of 1.0 mol %. A theoretical maximum of quantum efficiency of 183% is reached for 5 mol % of Yb2O3. PL characteristics (absorption cross section and emission lifetime) are further improved upon precipitation of crystalline LaBO3, where both Pr3+ and Yb3+ ions occupy La3+ sites with an assumedly statistical distribution and a high degree of partitioning.

Yb/P/Al共掺双包层光纤的制备与激光性能

Yb/P/Al codoped silica glass preforms are fabricated by MCVD process combined with the solution doping technique.Highly and homogeneously doping of Yb3+ is realized by optimization of the core composition and fabrication process.The Yb2O3 concentration in preform core is up to ~4 wt.% and Yb3+ fluorescence lifetime at 1080nm reaches 1 780 μs.Double-clad fibers with octagonal inner cladding are successfully drawn from the preform,the fiber core diameter is 7.5 μm and the clad absorption coefficicent is up to ~5 dB/m@976 nm.The operation of the cladding pumped all-fiber laser is demonstrated using Yb-doped double-clad fibers.Fiber lasers with output power of 5.15 W and slope efficiency of 76% are obtained.

Suppression of photo‐darkening effect by Ca additive in Yb‐doped silica glass fibre

It is found that Ca additive effectively suppresses the photo-darkening effect in Yb-doped silica fibre even at 6.0 wt% of high Yb2O3 concentration. Ca ion works as a stabiliser to maintain the Yb3+ valence state. It is hypothesised that this phenomenon may reflect the local charge balance effect in silica glass. This Yb-Ca co-doped silica fibre can be useful for high-power fibre lasers.

Study of Lanthanum Aluminum Silicate Glasses for Passive and Active Optical Fibers

We are reporting onSiO2‐Al2O3‐La2O3glasses—with and withoutYb2O3—suitable for nonlinear and fiber laser applications. We will also be presenting successful supercontinuum generation and fiber laser operation around 1060 nm in step‐index fibers. We optimized the glass compositions in terms of thermal and optical requirements for both a highLa2O3andYb2O3concentration and good compatibility with a silica cladding. We also produced bulk samples, unstructured fibers, and structured fibers with aSiO2‐Al2O3‐La2O3core and silica cladding for this purpose.