First laser emission of Yb 0.15 :(Lu 0.5 Y 0.5 ) 3 Al 5 O 12 ceramics.

We report the first laser oscillation on Yb0.15:(Lu0.5Y0.5)3Al12 ceramics at room temperature. At 1030 nm we measured a maximum output power of 7.3 W with a corresponding slope efficiency of 55.4% by using an output coupler with a transmission of T = 39.2%. The spectroscopic properties are compared with those of the two parent garnets Yb:YAG and Yb:LuAG. To the best of our knowledge these are the first measurements reported in literature achieved with this new host

Spectroscopic and laser characterization of Yb 0.15 :(Lu x Y 1-x ) 3 Al 5 O 12 ceramics with different Lu/Y balance.

We report a broad comparative analysis of the spectroscopic and laser properties of solid solution Lutetium-Yttrium Aluminum Garnet (LuYAG, (LuxY1-x)3Al5O12) ceramics doped with Yb. The investigation was mainly aimed to assess the impact of the Lu/Y ratio on the Yb optical and laser properties. Therefore we analyzed a set of samples with different Y/Lu balance, namely 25/75, 50/50 and 75/25, with 15% Yb doping. We found that the Yb absorption and emission spectra changed from YAG to LuAG when gradually increasing in Lu content. Regarding the laser emission, remarkable results were achieved with all samples. Maximum output power was 8.2 W, 7.3 W and 8.7 W for Y/Lu balance 25/75, 50/50 and 75/25 respectively, at 1030 nm; the slope efficiency and the optical-to-optical efficiencies approached or exceeded 60% and 50% respectively. The tuning range was investigated using an intracavity ZnSe prism. The broadest tuning range (998 nm to 1063 nm) was obtained with Y/Lu balance 75/25, whereas the emission of the other two samples extended from 1000 nm to 1058 nm. To the best of our knowledge, this is the first comparative analysis of Yb:LuYAG ceramics or crystals as laser host across such a broad range of Y/Lu ratios

Effect of reducing Lu3+Lu^{3+} content on the fabrication and scintillation properties of non-stoichiometric Lu3−xAl5O12Lu_{3}−_{x}Al_5O_{12}:Ce ceramics

$Lu_{3}−_{x}Al_5O_{12}$:Ce optical ceramics ($Lu_3−_{x}AG:Ce,$ x = 1, 2, 3 and 4 at.%, respectively) with $Lu^{3+}$ compositions ranging from 1 to 4 at.% below stoichiometry content were fabricated by solid state reaction method and further optimized by an air-annealing process. The effect of $Lu^{3+}$ deficiency on the optical, luminescence and scintillation properties of such a non-stoichiometric $Lu_3−_{x}Al_5O_{12}$:Ce ceramics was investigated. Significant influence in the material densification was found leading to strong changes in the transparency, radioluminescence (RL) and scintillation response of these ceramics. Within the range of 1–4 at.% $Lu^{3+}$ deficiency, LuAl antisite defects were suppressed effectively and the $Lu_3−_{x}AG:Ce$ ceramics displayed an extremely high RL intensity which reaches ∼4 times higher than that of the latest commercial LuAG:Ce single crystals while its transparency deteriorated. The microstructure, presence of foreign phases and charge traps acting in scintillation mechanism were also characterized by means of SEM, back scattered electron imaging and thermoluminescence techniques, respectively

Composition and properties tailoring in Mg2+Mg^{2+} codoped non-stoichiometric LuAG:Ce,Mg scintillation ceramics

A comprehensive study of the optical, radioluminescence and scintillation properties of both the $Lu^{3+}$ rich and $Lu^{3+}$ deficient non-stoichiometric $Lu_{3+x}AG:Ce,Mg$ $(Lu_{3+x}Al_5O_{12}$:Ce,Mg, x = −4, −1, +1 and +4 at.%) ceramics are performed, completed further by the microstructure and defects characterization. Small deviation from the stoichiometric composition as well as $Mg^{2+}$ codoping plays a crucial role in ceramic transparency, radioluminescence intensity and the timing characteristics of scintillation response. The LuAl antisite defects could be suppressed efficiently by controlling $Lu^{3+}$ content below stoichiometry of LuAG host. MgO $(Mg^{2+} ions)$ as effective sintering aids, can improve both the optical quality and scintillation performance (light yield, scintillation decay times and the ratio of fast decay components). We generally discuss the composition dependence of defects and properties tailoring. We also performed the systematic comparative study with the stoichiometric LuAG:Ce,Mg ceramic and the commercial BGO and LuAG:Ce single crystals

Optical properties of Er, Yb co-doped YAG transparent ceramics

The transparent polycrystalline erbium and ytterbium co-doped yttrium aluminum garnet (Er, Yb:YAG) ceramics with various Yb contents from 5% to 25% were prepared by the solid-state reaction and the vacuum-sintering technique. The in-line transmittances of the mirror-polished ceramics exceed 80% from the visible band to the infrared band. The samples are very compact with few pores. The average grain size of the Er,Yb:YAG ceramic is about 15 mu m. The upconversion luminescence spectra, infrared luminescence spectra and luminescence decay curves of the ceramics were observed and discussed. For 1%Er doped YAG ceramic, the best ion ratio of Yb(3+) and Er(3+) is around 15:1. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Effect of Tensile Strain on Thermal Conductivity in Monolayer Graphene Nanoribbons: A Molecular Dynamics Study

sensor

Effect of Li+Li^+ ions co-doping on luminescence, scintillation properties and defects characteristics of LuAG:Ce ceramics

Monovalent $Li^+$ codoped $Lu_3Al_5O_{12}$:Ce (LuAG:Ce) optical ceramics were fabricated by solid state reaction method and further optimized by an air-annealing process. Optical absorption, radioluminescence spectra and scintillation properties such as light yield, scintillation decay times and afterglow were measured and compared with those of the $Li^+$ free LuAG:Ce ceramic and the commercial LuAG:Ce single crystal samples. Positive effect of $Li^+$ codopant consists mainly in the significant increase of scintillation light yield, acceleration of scintillation decay as well as the decrease of afterglow intensity. With 0.3% Li codoping, the obtained LuAG:Ce,Li ceramic displays a light yield of ∼29200 ph/MeV at 10 μs shaping time, higher than that of the LuAG:Ce single crystal and optical ceramic scintillators ever reported. The partial conversion of the stable $Ce^{3+}$ to $Ce^{4+}$ centers and the shallow and deep traps effect suppression by the $Li^+$ codoping are discussed