Ytterbium Concentration Research Articles

Upconversion multicolor tuning in Er3+ and Yb3+ doped yttrium oxide prepared by precursor technique

The (Y0.9Er0.1-xYbx)2O3 (x = 0, 0.02, 0.05, 0.07, 0.08, 0.09) and Y1-(0.02+y)Er0.02YbyO3 (y = 0.05, 0.07, 0.09, 0.11) solid solutions have been synthesized by the precursor technique using mixed anhydrous formates. The crystal structure of ytterbium formate, Yb(HCOO)3, was established for the first time. The structural parameters and phase purity of the synthesized precursors and oxides were determined by X-ray phase analysis. The average sizes of crystallites are in the 60–80 nm range. The upconversion spectra of solid solutions exhibit a weak green and an intense red line attributed to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions. The green and red emissions of (Y0.9Er0.1-xYbx)2O3 and Y1-(0.02+y)Er0.02YbyO3 oxides are caused by two-photon conversion processes. The effect of dopant (erbium and ytterbium) concentration and Er3+/Yb3+ ratio on the intensity of upconversion emission were established, the contribution of upconversion green luminescence decreases with increasing the ytterbium concentration.

INFLUENCE OF MODIFICATION ON PROPERTIES OF ZSM-5 ZEOLITE IN THE REACTION OF TOLUENE ALKYLATION WITH ISOPROPANOL

Bimetallic catalysts based on ZSM-5 zeolite modified with ytterbium and nickel have been prepared. The influence of the concentration of ytterbium (1.7–5.0 wt.%) and nickel (1.0–1.5 wt.%) on the acidic, textural and catalytic properties of the zeolite in the reaction of alkylation of toluene with isopropanol in the temperature range of 300–3500C was studied. It has been shown that the unmodified zeolite HZSM-5 exhibits low selectivity (54.6–58.2%) for isopropyltoluenes (3-IPT, 4-IPT, and 2-IPT) than the modified catalysts. In addition, the content of the valuable 4-IPT isomer does not exceed 44.2%. Modification of HZSM-5 with ytterbium in an amount of 5.0 wt.% leads to an increase in the selectivity for isopropyltoluenes up to 68.7%, and the selectivity for 4-IPT up to 68.8%. Additional modification of the 3%-Yb-HZSM-5 catalyst with nickel in the amount of 1.0 wt.% prevents the formation of 2-IPT and promotes an increase in the yield of 4-IPT. The modified catalysts were characterized by XPA, BET, BJH, and ammonia TPD. Modification, calcination, and successive treatment of the catalyst with air and hydrogen leads to a dispersed distribution of Yb2O3 and metallic nickel oxide nanoparticles in the outer surface and in the pores of the zeolite, which causes a decrease in the specific surface area, total pore volume, and an increase in the fraction of mesopore volume. As a result of the interaction of modifiers with acidic OH groups of the zeolite, the concentration of strong Brønsted acid sites decreases and new, stronger Lewis acid sites form. All this has a decisive effect on the selectivity of 4-IPT formation and the stability of the bimetallic catalyst. The maximum selectivity for 4-IPT on a 3% Yb 1.0% Ni/HZSM-5 bimetallic catalyst is achieved at 3300C and is 71.5% at a toluene conversion of 24.6%.

Associations between maternal urinary rare earth elements during pregnancy and birth weight-for-gestational age: Roles of cord blood vitamin D levels

Prenatal exposure to rare earth elements (REEs) may contribute to adverse birth outcomes in previous studies. Cord blood vitamin D has been suggested to modify or mediate the effects of environmental exposures. However, none has investigated these roles of cord blood vitamin D in the associations of prenatal exposure to REEs with fetal growth. Maternal trimester-specific urinary concentrations of 13 REEs, cord blood total 25-hydroxyvitamin D at delivery, and birth weight (BW)-for-gestational age (GA) were determined in 710 mother-newborn pairs from Wuhan, China. Higher maternal average urinary concentrations of europium (Eu), gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er), and ytterbium (Yb) across three trimesters, either individually or jointly, were significantly associated with lower BW-for-GA Z-scores and higher odds of small for gestational age (SGA) [β = −0.092; 95 % confidence interval (CI): −0.149, −0.035 for BW-for-GA Z-scores, and odds ratio = 1.60; 95 % CI: 1.14, 2.24 for SGA involved in each unit increase in weighted quantile sum index of REEs mixture]. When stratified by cord blood vitamin D levels, the associations mentioned above persisted in participants with relatively low vitamin D levels (<13.94 μg/L, the first tertile of distribution), but not among those with relatively high levels (≥13.94 μg/L) (all p-values for interaction < 0.05). The mediation analyses taking account of exposure-mediator interaction showed that the relationships between REEs (as individual and mixture) exposure and lower BW-for-GA were partly mediated through decreasing cord blood vitamin D levels. The proportions mediated by cord blood vitamin D levels were 24.48 % for BW-for-GA Z-scores and 29.05 % for SGA corresponding to the REEs mixture exposure. Conclusively, our study revealed that prenatal exposures to Eu, Gd, Dy, Ho, Er, and Yb were related to fetal growth restriction. Cord blood vitamin D might alleviate toxic effects of these REEs and its reduction might partly mediate REE-induced fetal growth restriction.

High ytterbium concentration Yb/Al/P/Ce co-doped silica fiber for 1-µm ultra-short cavity fiber laser application.

We demonstrate a high ytterbium concentration Yb/Al/P/Ce co-doped silica fiber by conventional modified chemical vapor deposition (MCVD) technology and solution doping process. The fiber has a Yb concentration of about 2.5 wt%, and the corresponding core absorption coefficient is measured to be ∼1400 dB/m at 976 nm. The gain coefficient was measured to be approximately 1.0 dB/cm. It is found that the Yb/Al/P/Ce co-doped silica shows a lower photodarkening-induced equilibrium loss of 52 dB/m at 633 nm than the Yb/Al/P co-doped silica fiber of 117 dB/m. Using the heavily Yb3+-doped silica fiber, a compact and robust ultrashort cavity single-frequency fiber laser was achieved with a maximum output power of 75 mW and a linewidth of 14 kHz. Furthermore, a compact passively mode-locked fiber laser (MLFL) with a repetition rate of 1.23 GHz was also proposed using our developed Yb-doped fiber. The laser properties of the proposed lasers were systematically investigated, demonstrating the superior performance of this fiber in terms of photodarkening resistance and ultrashort-cavity laser application. Furthermore, utilizing an all-fiber structure based on silica-based fiber offers the significant advantage of high stability and reliability.

Determination of the energy transfer parameters in modeling the luminescence kinetics of Er3+ and Yb3+ ions in fluorophosphate glasses with a low phosphate content

The fluorophosphate glasses with composition of Ba(PO3)2 – AlF3–CaF2 – MgF2–BaF2 – SrF2–YbF3 – ErF3 were synthesized and their spectroscopic properties were studied. The main attention here was paid to studying the luminescence kinetics Yb3+ (1040 nm) and Er3+ (1550 nm, 655 nm and 540 nm). It has been found that the population of the 4I13/2 (Er3+) level and the relaxation of the 2F5/2 (Yb3+), 4F9/2, and 2H11/2+4S3/2 (Er3+) levels are close to exponential and the probabilities of these processes are well approximated by linear functions with respect to the ytterbium concentration. All this led to the conclusion that the migration-accelerated energy transfer makes a significant contribution to the population and deactivation of these energy levels. A scheme of the main energy transfer channels in an ensemble of ytterbium and erbium ions and the corresponding system of rate equations are proposed. On the basis of these equations, mathematical modeling of the luminescence kinetics of ytterbium and erbium ions was carried out and the energy transfer parameters were estimated.

Extraction elements of ytterbium(III) in metallic ore wastewater with combination of PAN microtube ultrafilter device and organic P-204

Rare-earth metallic ore in Siping city had produced wastewater containing ytterbium, which has caused certain environmental pollution. In view of the low removal efficiency of ytterbium in wastewater, we developed a novel PAN microtube ultrafilter device with organic P-204 system (UF-OP). The UF-OP had organic P-204 system containing wastewater part with buffer solution acetic acid and enrichment part with nitric acid solution and organic P-204[Di(2-ethylhexyl) phosphoric acid] dissolved in gasoline. Many factors of ytterbium(III) extraction using UF-OP need to explore. The effects of hydrodynamic properties and UF system parameters on the UF-OP process for ytterbium(III) extraction were also studied. The experimental results show that the best extraction conditions of ytterbium(III) were obtained as that nitric acid concentration was 4.00 mol/L, organic P-204 concentration was 0.150 mol/L, and O/W was 0.5 in the enrichment part, and pH value was 4.80 in the wastewater part. Ionic strength of metallic ore wastewater had no obvious effect on ytterbium(III) extraction. When cinit of ytterbium(III) concentration was 1.48 × 10−4 mol/L, the extraction percentage of ytterbium(III) was up to 94.8% in 160 min. The study results would provide theoretical and technical support for the treatment of wastewater containing ytterbium in metallic ore.

Properties of Silica Based Optical Fibers Doped With an Ultra-High Ytterbium Concentration

Silica-based optical fibers with an ultra-high Yb concentration were systematically studied. Three the most commonly used in industry glass matrixes for active fiber core were investigated: aluminosilicate, phosphosilicate and aluminophosphosilicate. For all the glass hosts optical fibers doped with a record high concentration of Yb in a glass core were fabricated utilizing an all-gas-phase deposition based on MCVD technology. The factors limiting increase of Yb content in glasses and fibers were revealed. For the first time it was shown that highly Yb-doped fibers could nearly completely lose their active properties and the most probable reason for that is concentration quenching of luminescence.

Investigation of up/down-converted luminescence and related mechanisms in Ho3+/Yb3+ co-doped Y2Zr2O7 highly transparent ceramics as phosphor material

Via solid state reaction, Ho3+/Yb3+ co-doped Y2Zr2O7 (YZO) transparent ceramics with different ytterbium concentration were successfully prepared. Highest in-line transmittance of samples reaches over 75% in both visible and near-infrared region. The homogeneity and microstructure of powders and ceramics were investigated through XRD and SEM characterizations. The luminescence results show that under excitation at ultraviolet (UV) and near-infrared (NIR) source, strong green emission peaks were observed and corresponding energy-conversion mechanism such as cooperative energy transfer (CET) were applied to explain the transition mechanism. Combined with the excellent optical properties and high temperature resistance, these results suggest that Ho3+/Yb3+ co-doped Y2Zr2O7 (YZO) transparent ceramics are promising novel phosphor material under different circumstance.

Synthesis, characterization, and evaluation of the photocatalytic properties of zinc oxide co-doped with lanthanides elements

Zinc oxide nanoparticles (NPs) co-doped with various concentrations of lanthanides cerium and ytterbium (Zn1-2xCexYbxO, x = 0.0, 0.01, 0.03, and 0.05) were synthesized via the sol-gel auto-combustion method. All prepared samples including CYZO0 (x = 0.0), CYZO1 (x = 0.01) CYZO3 (x = 0.03), and CYZO5 (x = 0.05) were subsequently characterized. The effects of the concentration of Ce and Yb on the structural, optical, and photocatalytic properties of ZnO NPs were deeply explored. The structural analysis showed that the as-synthesized samples were matched with a hexagonal structure. The co-doping altered the crystal structure of the material. The lattice constants increased with increasing the concentration of Ce and Yb ions. The crystallite size was reduced from 53.24 ± 0.05 nm CYZO0 to 52.28 ± 0.05 nm, 34.90 ± 0.05 nm, and 36.85 ± 0.05 nm for CYZO1, CYZO3, CYZO5, respectively. UV–Vis analysis showed a variation in the bandgap energy values with Yb and Ce co-doping. The photocatalytic activities of Yb and Ce co-doped ZnO were assessed by taking methyl orange (MO) as an organic dye. The absorption peaks at 464 nm for MO dye reduced progressively with prolonged exposure time indicating the presence of the photocatalytic degradation reaction of MO. The constant rate k was found to be 0.027 min−1 for CYZO0, and 0.024 min−1 for CYZO1, and then sharply decreased to 0.0064 min−1, and 0.0065 min−1 for CYZO3 and CYZO5, respectively. It is suggested that the photocatalytic efficiency is intensely dependent on the synergistic effect of both Yb and Ce co-doping.

Comparison of two software programs for fitting one- and two-compartment age-dependent non-linear digestion models for ruminants: empirical data

Context The total mass and kinetics of feed particles through the digestive tract affect feed intake, nutrient excretion and emissions by ruminants. Use of models to calculate digesta kinetics parameters will assist managers in mitigating enteric methane emission and producing food more sustainably. Aims We evaluated two software programs for fitting parameters to one- and two-compartment age-dependent digesta kinetic models from faecal-marker concentration datasets. Methods We examined biases (mean differences) and standard deviations (differences) of one-compartment (G2) and two-compartment (G2G1) models with a gamma-2 distribution in the age-dependent compartment when parameterised with two different software programs (R or SAS), using 41 datasets of ytterbium concentrations in faecal samples collected at discrete times. Faecal-marker concentration datasets were fitted to G2 and G2G1 models with each software program. The resulting model parameters, K0, λ or λ1, K2 and τ, were used to calculate the digesta kinetics parameters: particle passage rate, gastrointestinal dry matter fill, faecal dry matter output, gastrointestinal mean retention time and rumen retention time. We evaluated bias and standard deviation for model and digesta kinetic parameters across the entire range of average values, but also within low, medium and high percentile range-of-value subsets (5–35%, 35–65% and 65–95%) between software programs. Key results When datasets were fitted to the G2 model, all converged for both software programs, but when fitted to the G2G1 model by the SAS program, three observations did not converge. Bias and standard deviation of differences between software packages were small, but the G2G1 model produced smaller bias and standard deviation of differences. Bias and standard deviation of differences for digesta kinetics estimates across the percentile groups did not vary linearly for most model estimates and were small relative to the magnitude of the values. Conclusions Model parameters and digesta kinetics estimates derived from R and SAS software programs can be used interchangeably in nutritional modelling. Two-compartment models (G2G1) can be more problematic to fit, but residual mean-square errors are usually smaller. Implications Model parameters from both G2 and G2G1 models can be used to derive unbiased estimates of digesta kinetics from either R or SAS software program.

Absorption properties of bromide photo-thermo-refractive glasses doped with Ytterbium

In this work bromide photo-thermo-refractive glasses with different Ytterbium concentration were explored. It is shown that UV irradiation and subsequent heat treatment of samples with Yb 2 mol.% causes significant red-shift absorption line from 410 nm with temperature lower than Tg to 517 nm with temperature Tg +60 °C. For small concentration of Yb (0,1 mol. %) maximum red-shift in plasmon resonance absorption band is shown as 485 nm and it is the same for heat treatment temperatures from Tg +20 °C to Tg +60 °C.

Spectroscopic and optical investigations on Er3+/Yb3+co-doped bismuth–boroleadlithium glasses for solid state laser applications

Erbium–Ytterbium ions co-doped Bismuth boroleadlithium glasses have been found to be a viable option for a variety of photonics applications. In the present article, a small content of erbium oxide (0.5) and ytterbium (0, 0.5, 1, 1.5 and 2 mol%) assorted with bismuth boroleadlithium glasses were produced using the traditional melt-quenching method. The detailed structural and optical properties of glasses were analyzed through various characterization techniques viz., XRD, FESEM, DTA, FT-IR, Optical absorbance (OA) and Photoluminescence (PL). The results of XRD and SEM confirmed the non-crystalline nature of the glasses and the local structural changes were perceived by FTIR and DTA analysis. From OA data the calculated J-O intensity parameters (Ωλ where λ = 2, 4 and 6) of the present glasses followed the trend Ω2>Ω6>Ω4, it shows that the Yb–O bond has a higher degree of covalency. Moreover, the values (Ω4/Ω6 < 1) of spectroscopic quality factor signifying the suitability of laser transitions. Obtained 4F9/2 → 4I15/2 (red) transition have more intense than 2H11/2 → 4I15/2 (green) transition with co-doped Er/Yb ions. It is also noticed that the luminescence properties enhanced with increasing ytterbium concentration up to 1 mol% and then reduced due to luminescence quenching. CIE chromaticity coordinates and CCT (correlated color temperature) values were measured from the luminescent spectra to estimate the quality of the light emitted for laser generation. Overall, the acquired experimental results of the as-developed glasses revealed their appropriateness for the generation of efficient fiber amplifiers and solid-state lasers.

Nano Silica application for inducing rice resistance and the possibility for Ytterbium Rare Earth Elements green mining

There is a growing interest and recognition of Silicon (Si) in plants to increase growth, productivity, and plant resistance. This research examines the role of Nano Silica to increase yield and resistance. This study set out to assess the effect of hydrophilic fumed Nano Silica application with the frequency of 1×, 2×, 3×, and 4× applications respectively with three replications using RCBD as well as SEM-EDX and XRF analysis. Nano Silica frequencies showed a distinctive decrease of damage intensity at the 3× and 4× applications. The rice husk increases of metal-like surface appearance as more Nano Silica frequency was applied. It is proposed that Nano Si induced plant resistance through the modification of surface layer and stronger plant tolerance against environmental stress. The most unexpected observation to emerge was the Ytterbium (Yb) concentration known as a Rare Earth Elements at the 3× and 4× Nano Si applications. This indicates that Nano Silica application provides insights and opportunities to Nano Si application on Rice for the purpose of acquiring Ytterbium from farmland. Nano Silica can play an important role as a new method in addressing the Ytterbium green mining.

Effect of Yb doping on structural, optical and induced ferromagnetism in SrSnO3 perovskite nanostructures

SrSnO3 nanostructures with different Ytterbium (Yb) concentrations are synthesized by chemical precipitation method. XRD and Ritveld refinement pattern confirm the formation of well crystalline orthorhombic perovskite structure. The calculated crystallite size, strain and lattice parameters values reveal the effect of dopant on Sr–Sn–O lattice. The chemical bonding, M − O vibrations, and variations in the local structural disorder was examined by vibrational spectroscopic analysis. Poly dispersed particles with rods like shape for pure and Yb-5% doped samples were identified. Oxidation states and oxygen vacancy of the prepared samples were analyzed by XPS studies. The UV–Visible spectra showed a steep absorption due to Yb interaction with the host lattice. The PL spectra showed a bluish-green emission evidenced the presence of vacancies such as oxygen. EPR studies confirm the role of Yb ions in the local environments. Room temperature magnetization studies demonstrated diamagnetic behavior in undoped sample and weak ferromagnetism for all the Yb doped SrSnO3 samples. Hence, the dopant (Yb) ions produce a change in the local structure, surface morphology and induced ferromagnetic behavior in Sr–Sn–O lattice. The induced ferromagnetic transition upon Yb doping was explained by defects and vacancies.

Ytterbium-doped chloride photo-thermo-refractive glass: spectral, luminescent, and gain properties

We developed a new chloride photo-thermo-refractive glass doped with ytterbium ions. The dependence of optical and spectral-luminescent characteristics on ytterbium concentration has been studied. Concentration dependence of excited state decay time has been analyzed taking into account the self-trapping and self-quenching mechanisms. The optimum concentration of ytterbium ions in chloride photo-thermo-refractive glass has been determined. Other important spectroscopic parameters such as absorption and emission cross-sections, radiative lifetimes, pump saturation, and minimum pump intensities have been obtained using absorption and emission measurements and theoretical approaches such as Fuchtbauer-Landenburg and McCumber theories. The evolution of the gain cross-section spectrum as a function of a population inversion parameter has been performed. Results of this study show that the ytterbium-doped chloride photo-thermo-refractive glass demonstrates good spectroscopic and luminescent properties for laser and gain application.

Particulate rare earth element behavior in the North Atlantic (GEOVIDE cruise)

Abstract. Particulate concentrations of the 14 Rare Earth Elements (PREE), yttrium, and 232-thorium were measured in 200 samples collected in the epipelagic (ca. 0–200 m) and mesopelagic (ca. 200–1500 m) zones of the North Atlantic during the GEOVIDE cruise (May/June 2014, R/V Pourquoi Pas?, GEOTRACES GA01), providing the most detailed snapshot of the PREE distribution in the North Atlantic so far. Concentrations of particulate cerium (PCe) varied between 0.2 and 16 pmol L−1, while particulate neodymium (PNd) concentrations ranged between 0.1 and 6.1 pmol L−1. Particulate ytterbium (PYb) concentrations ranged between 0.01 and 0.50 pmol L−1. In addition, this study showed that PREE distributions were also controlled by the biological production in the upper sunlit ocean and by remineralization processes in the mesopelagic area. Low surface concentrations combined with normalized PREE patterns displaying a negative Ce anomaly and HREE enrichments pointed to freshly formed biogenic particles imprinting the seawater signature. A significant relationship between biogenic silica (BSi) and PHREE was also observed in the Labrador and Irminger seas, due to the occurrence of strong diatom blooms at the sampling time. In order to identify dissolved-particulate processes independent of the ionic radius, we used PHo∕PY ratios and showed that absorption processes were predominant in the upper ocean, while adsorption processes dominated at deeper depths. This study highlighted different lithogenic fractions of PREE and dispersion depending on the shelf: off the Iberian margin, up to 100 % of the PREE were determined to have a lithogenic origin. This lithogenic input spread westward along an intermediate nepheloid layer (INL), following isopycnals up to 1700 km away from the margin. In contrast, along the Greenland and Newfoundland margins, the circulation maintained lithogenic inputs of PREE along the coasts.

Anatase–Rutile Transition and Photo-Induced Conductivity of Highly Yb-Doped TiO2 Films Deposited by Acid Sol–Gel Dip-Coating Method

A method to prepare Yb-doped TiO2 is proposed, using titanium isopropoxide and ytterbium oxide. Thin films and powders are produced through the sol–gel technique where the Yb concentrations are 0.01 at.%, 0.02 at.%, 1 at.%, 2 at.% 4 at.% and 8 at.%. The increase in the doping concentration intensifies gradually the sample transparency for the whole observed spectrum and reaches the transparency degree of the undoped sample with the highest concentration of ytterbium. By means of x-ray diffraction (XRD) we find that the solution’s pH leads to the formation of a rutile structure which is compensated for by lanthanide doping, inhibiting the anatase–rutile phase transformation. Then, the XRD profile depends on the Yb concentration, being mostly anatase for undoped and highly (8 at.%) doped samples, with mixed ratios of these two phases in other concentrations. Maintaining an acid solution leads to fewer intergrain defects in the rutile structure contributing to higher conductivity. Photo-induced investigation of 8 at.% Yb-doped thin film, using several light sources leads to distinct behavior concerning the excitation of intra-bandgap states and/or electron–hole pairs. This result helps to understand the electronic transport in Yb-doped TiO2 and shows that devices based on its conductivity may have improved performance by irradiation with controlled light energy.

Structural and radiation shielding properties of BaTiO3 ceramic with different concentrations of Bismuth and Ytterbium

This study aims to explore the effect of Bi2O3 and Yb2O3 on the structural and radiation shielding properties of BaTiO3 ceramic samples fabricated by solid-state reaction and high-energy ball milling techniques. X-ray diffraction (XRD) spectra revealed that the current ceramic samples have a tetragonal phase. Fourier Transform Infrared (FTIR) results showed a peak at 1435 cm−1 for all ceramics that attributed to Ba–Ti–O. Various physical properties like density, packing density, molar volume, and Poisson's ratio were calculated for the prepared ceramic samples. The highest concentration of Bi2O3 (C3) exhibited the highest density values (5.562 g/cm3), packing density (0.630), and Poisson's ratio (0.279), whereas the high concentration of Yb2O3 (C6) had a density of 4.731 g/cm3, a packing density of 0.529, and a Poisson's ratio of 0.237. In addition, different radiation shielding properties were determined by using the Phy-X program for all ceramic samples. The mass attenuation coefficient (μ/ρ) values for C3 and C6 at 1 MeV were 0.065 and 0.062 cm2/g, respectively. Based on the calculated (μ/ρ), the C3 sample revealed a promising half-value layer (HVL), mean free path (MFP), and effective atomic number (Zeff). Regarding the neutron shielding properties, the effective removal cross-section (ΣR) values for C1, C2, C3, C4, C5 and C6 were 0.101, 0.098, 0.095, 0.089, 0.88 and 0.085 cm−1, respectively. In this regard, C1 showed the highest ΣR compared with the other prepared samples. In conclusion, C1 and C3 samples have superior neutron and photon shielding features compared with the other prepared ceramics. In light of these obtained results, the fabricated ceramics can be concluded to be very helpful for photon and neutron shielding applications.

Up-conversion study of CaF2 based oxy-fluoride core-shell particulate nano-glass ceramics via sol-gel method: Effect of Yb3+ concentration and cell viability study

The current study delineates the synthesis and characterization of CaF2 based Oxy-fluoride glass-ceramics with Erbium (1 mol%) and with varying Ytterbium concentration (1 mol% and 5 mol%) doping of fluoride source. The influence of yb3+ concentration on thermal, structural, and luminescence properties were investigated and analyzed through a sol-gel process. The differential thermal analysis (DTA) specified that the glass transition (Tg) temperature decreases with the increase of Yb3+concentration in the prepared glass-ceramics. The microstructural study performed by transmission electron microscope (TEM), indicates the core-shell structure of glass-ceramics nanoparticles in between 10–50 nm range. The incorporation of Er3+ and Yb3+ into the crystalline matrix was confirmed and analyzed from X-ray diffraction (XRD) analysis. The increased crystal size according to increased temperatures shows the CaF2 crystal growth. The up-conversion luminescence properties of the prepared nano-glass ceramics were tested by using a 980 nm laser. The photoluminescence emission showed two peaks at green (548 nm and 528 nm) emission and one at red emission (626 nm). Additionally, the cell viability study of the Er3+-Yb3+ doped CaF2 nano glass-ceramics was performed using MG-63 osteoblast cells and it shows significant cell growth as compared to control over a period of 24 h. The result confirmed that the prepared nano-glass-ceramics can be a potential optical material for bio-imaging.

Ultra-low NA step-index large mode area Yb-doped fiber with a germanium doped cladding for high power pulse amplification.

High concentration rare earth doped, large mode area (LMA) step-index fibers, which feature a very high cladding absorption per unit length at the pump wavelength, high efficiency, and excellent beam quality, are ideal for high power pulsed fiber lasers/amplifiers where large effective mode areas and short device lengths are crucial in order to reduce detrimental nonlinear effects associated with high peak power operation. In this Letter, we realize low numerical aperture (NA) high absorption fibers, simply by employing a germanium (Ge)-doped cladding rather than a pure silica cladding to offset the high refractive index associated with using a high concentration of ytterbium (Yb) in the core. This approach allows us to separate the two inter-linked fiber design parameters of pump absorption and NA in a step-index fiber. Using a conventional modified chemical vapor deposition process combined with solution doping, a low NA (0.04), LMA (475µm2) silica fiber is fabricated with a cladding absorption value of >20dB/m, which is the highest value among LMA step-index fibers with NA<0.06 so far reported to the best of our knowledge. The fabricated Yb-doped fiber was tested in a high-power picosecond amplifier system and enabled the generation of 190 ps laser pulses with a 101 µJ pulse energy and 0.5 MW peak power at an average power of 150 W.