Fabrication and laser properties of transparent Yb:YAG ceramics

High optical quality transparent Yb:YAG laser ceramics have been successfully fabricated by a vacuum reactive sintering method. Commercial Al2O3 powder and co-precipitated Y2O3 and Yb2O3 powders were used as the raw materials. In-line transmittances at 1300 nm and 400 nm were measured to be 83.6% and 81.8% respectively for a 3 mm thick mirror polished Yb:YAG ceramics sample. Continuous wave (CW) lasing at the wavelength of 1030 nm was achieved when pumped by a 940 nm fiber coupled laser diode. A slope efficiency as high as 62.7% was obtained

Fabrication and properties of high quality transparent Ho:YAG ceramics

High quality holmium doped Yttrium Aluminum Garnet (YAG) transparent ceramics were fabricated by a reactive sintering method under vacuum. Fully dense Ho:YAG ceramics with the average grain size of ~ 10 μm were obtained after vacuum sintering at 1780 for 8 h. The optical properties, microstructures and photoluminescence spectra of the fabricated Ho:YAG ceramics were investigated. The transmittances of Ho:YAG ceramic are higher than 82% at 400 nm and 84% at 2400 nm. The absorption coefficient was 1.32 cm-1 for 1.5 at.% Ho:YAG at 1907 nm. And the absorption cross section of the Ho:YAG ceramic is 0.645×10-20 cm2

Fabrication and spectroscopic properties of transparent Yb:YAG laser ceramics

Yb3+ doped YAG ceramics have been successfully fabricated using a vacuum reactive sintering method. High purity Y2O3, Al2O3 and Yb2O3 powders were used as the starting materials. Samples of 5.0 at.% Yb3+ doping concentration have been obtained. The in-line transmittance of the sample reaches 84% at 1100 nm wavelength. The absorption and emission bandwidth were measured to be 19.5 nm and 11.07 nm respectively. The results show that Yb:YAG ceramics will be a promising laser material for high power and ultrafast laser applications

The effect of MgO and SiO2 codoping on the properties of Nd:YAG transparent ceramic

Nd:YAG transparent ceramics were fabricated by a reactive sintering method under vacuum using SiO2, MgO and compound additives (SiO2 and MgO) as sintering aids. The effects of SiO2 and MgO on the microstructure and sintering process of Nd:YAG ceramics were studied. High quality Nd:YAG ceramics with compound sintering aids obtained by vacuum sintering at 1780 °C are composed of grains of the size ∼10 μm, and their transmittance is 82% at 400 nm. It was found the absorption coefficient of 1.0 mol% Nd:YAG ceramic was 8.6 cm−1 at 808 nm and its absorption cross section was calculated to be 6.26 × 10^−20 cm2

Fabrication and upconversion luminescence of highly transparent Er:YAG ceramics

Highly transparent Er:YAG ceramics with different Er concentration were fabricated by a solid-state reaction and vacuum sintering method. The optical properties, the microstructure and the upconversion luminescence of the Er:YAG ceramics were investigated. For 3 mm thick samples, the in-line transmittances of the as-fabricated Er:YAG ceramics at the wavelength of 1100 nm and 400 nm were about 84% and 82%, respectively, which was very close to the theoretical transmittance of YAG ceramics. The micrograph of the Er:YAG transparent ceramics exhibited a pore-free structure and the average grain size was about 10 μm. The grain boundary of the ceramics was clean and no secondary phase was detected. When pumped by a 980 nm LD, the strong green and red upconversion luminescences in the Er:YAG ceramics were observed. The different upconversion mechanisms depending on Er concentration in the Er:YAG ceramics were also discussed

Multi-Channel Metabolomics Analysis Identifies Novel Metabolite Biomarkers for the Early Detection of Fatty Liver Disease in Dairy Cows

Fatty liver disease, a type of metabolic disorder, frequently occurs in dairy cows during the parturition period, causing a high culling rate and, therefore, considerable economic losses in the dairy industry owing to the lack of effective diagnostic methods. Here, metabolite biomarkers were identified and validated for the diagnosis of metabolic disorders. A total of 58 participant cows, including severe fatty liver disease and normal control groups, in the discovery set (liver biopsy tested, n = 18), test set (suspected, n = 20) and verification set (liver biopsy tested, n = 20), were strictly recruited and a sample collected for their feces, urine, and serum. Non-targeted GC-MS-based metabolomics methods were used to characterize the metabolite profiles and to screen in the discovery set. Eventually, ten novel biomarkers involved in bile acid, amino acid, and fatty acid were identified and validated in the test set. Each of them had a higher diagnostic ability than the traditional serum biochemical indicators, with an average area under the receiver operating characteristic curve of 0.830 ± 0.0439 (n = 10) versus 0.377 ± 0.182 (n = 9). Especially, combined biomarker panels via different metabolic pipelines had much better diagnostic sensitivity and specificity than every single biomarker, suggesting their powerful utilization potentiality for the early detection of fatty liver disease. Intriguingly, the serum biomarkers were confirmed perfectly in the verification set. Moreover, common biological pathways were found to be underlying the pathogenesis of fatty liver syndrome in cattle via different metabolic pipelines. These newly-discovered and non-invasive metabolic biomarkers are meaningful in reducing the high culling rate of cows and, therefore, benefit the sustainable development of the dairy industry

Diode pumped highly efficient Yb:Lu3Al5O12 ceramic laser

A diode pumped ytterbium-doped lutetium aluminum garnet (Yb:LuAG) ceramic laser is reported for the first time to our knowledge. Using the solid state reactive vacuum sintering technique we have successfully fabricated high optical quality Yb:LuAG ceramics. We show that even with an uncoated Yb:LuAG ceramic sample a maximum output power of 7 W could be achieved under 13 W absorbed pump power, and the laser has a slope efficiency as high as 63%. Considering that Yb:LuAG has higher thermal conductivity than Yb:YAG under heavy doping situation, Yb:LuAG ceramic could be an attractive laser gain medium for the high power solid state lasers applications

Fabrication and properties of highly transparent Er:YAG ceramics

Highly transparent Er:YAG ceramics with different Er doping concentrations were fabricated by a reactive sintering method under vacuum. The optical properties and the microstructures of the Er:YAG ceramics were investigated. For 3 mm thickness samples, the in-line transmittances of the as-fabricated Er:YAG ceramics at the wavelength of 1100 nm and 400 nm were about 84% and 82%, respectively. The micrograph of the Er:YAG transparent ceramics exhibited a pore-free structure and the average grain size was about 10 μm. The grain boundary of the ceramics was clean and no secondary phase was detected. The absorption and emission spectra, the fluorescence decay traces of the Er:YAG ceramics were measured and discussed. The ceramics obtained may have potential use for eye-safe solid-state lasers partly replacing Er:YAG single crystals

Polycrystalline Ho:YAG transparent ceramics for eye-safe solid state laser applications

High optical quality holmium doped yttrium aluminum garnet (Ho:YAG) transparent ceramics that contained 0.5–2.0 at.% holmium additives were fabricated by a reactive sintering method under vacuum. Fully dense Ho:YAG ceramics with the average grain size of ~10 μm were obtained after vacuum sintered at 1780°C for 8 h. The in-line transmittances in the visible and infrared region are higher than 82% and 84%. The absorption coefficients of the 0.8, 1.0, 1.5, and 2.0 at.% Ho:YAG ceramics at 1907 nm was calculated to be 0.72, 0.89, 1.32, and 1.78 cm−1, respectively. The absorption cross-section of Ho:YAG ceramic was 0.645 × 10−20 cm2. The 1.5 and 2.0 at.% Ho:YAG ceramic slabs were in-band pumped by a Tm:fiber laser at 1907 nm. A maximum output power of 20.6 W at 2097 nm was obtained with a corresponding slope efficiency of 60.9%