Characterization of the lasing properties of a 5%Yb doped Lu_2SiO_5 crystal along its three principal dielectric axes

The laser performance of a 5% Yb doped Lu2SiO5 (Yb:LSO) has been investigated in quasi continuous-wave pumping regime along the three principal dielectric axes of the crystal, to obtain a complete characterization of its laser properties. The comparison among the obtained results for differently polarized lasers, in term of relative slope efficiency and absolute efficiency, allows the exploitability of different orientations of the material in order to be determined to obtain efficient laser sources. The laser slope efficiency and the energy conversion efficiency were similar for emission polarized along the three indicatrix axes, with noticeable maximum values of slope efficiency around 90% for polarization along the Y and Z axes. Tunable laser action has been obtained in the range 990 nm - 1084 nm, with sizeable differences in the shape of the tuning curve for polarization along the X, Y and Z axes. In particular, the tuning for polarization along the Z axis is relatively flat and uniform in the range 1023 nm - 1083 nm

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

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

Compositional regulation of multi-component GYGAG:Ce scintillation ceramics: Self-sintering-aid effect and afterglow suppression

(Gd,Y,Ce)3(YxGa1−x)2GaAl2O12 (GYGAG:Ce) scintillation ceramics with different Y excess, where x = 0.005−0.08, were fabricated by the solid-state reaction method. The effects of stoichiometry on the phase composition, optical quality, and microstructure of GYGAG:Ce ceramics were analyzed. GYGAG:Ce ceramics have a pure garnet phase and obtain good in-line transmittance when x < 0.04, while more Y excess leads to the creation of the secondary phase. The change of x value influences the sintering behavior of the GYGAG:Ce ceramics: The excess of Y works as the self-sintering aid and significantly reduces the sintering temperature of ceramics. When x = 0.01–0.04, the X-ray excited luminescence (XEL) spectra and light yields of GYGAG:Ce ceramics are similar. The fast scintillation decay time and afterglow intensity of GYGAG:Ce ceramics show a slight decrease with increasing x value. Finally, additional 50–500 ppm MgO and 100–500 ppm CaO were introduced to the GYGAG:Ce ceramic with x = 0.04, and both were found to significantly increase the fast scintillation component and reduce the afterglow intensity by two orders of magnitude to 0.01% after X-ray cut-off

Luminescent properties of RE

The optical properties of undoped RE2O3 (RE  =  Lu, Sc, Y) sesquioxides, which were prepared by different methods, are reported. Luminescent characteristics, including emission, excitation spectra as well as luminescence decay kinetics were studied in a wide spectral range. The main intrinsic emission bands are located in ultraviolet region and the origin of these luminescent bands is different owing to the different electronic structure. In present paper, the spectral characteristics of these samples are considered and compared with those studied before; the origin of the intrinsic bands is discussed

Ultrabright and Highly Efficient All‐Inorganic Zero‐Dimensional Perovskite Scintillators

Low-dimensional halide perovskites with excellent luminescent properties have become leading candidates for optoelectronic and radiation-detection applications. In this work, Tl cation is incorporated into 0D perovskite Cs3Cu2I5 host and an ultrabright and efficient scintillator is developed for X-ray and γ-ray detection. The Tl-doped Cs3Cu2I5 crystals exhibit a high photoluminescence quantum efficiency of 79.2%. The radioluminescence emission of Cs3Cu2I5:Tl crystal under X-ray excitation consists of a self-trapped exciton emission at 440 nm and a Tl-related emission at 510 nm at room temperature. With optimized Tl doping, the Cs3Cu2I5 not only demonstrates about five-times enhanced steady-state scintillation yield up to 150 000 photons/MeV and an improvement of X-ray detection limit from 103.6 to 66.3 nGy s−1, but also maintains an extremely low afterglow of 0.17% at 10 ms after X-ray cut-off. The Cs3Cu2I5:Tl also possess a remarkable energy resolution of 3.4% at 662 keV and an ultrahigh light yield of 87 000 photons/MeV under 137Cs γ-ray radiation

Optical, luminescence and scintillation characteristics of non-stoichiometric LuAG:Ce ceramics

Non-stoichiometric $Lu_{3+x}Al_{5}O_{12}:Ce$ ($Lu_{3+x}$AG:Ce, x=1, 2, 3 and 4 %) ceramics were fabricated by solid state reaction method and further optimized by an air-annealing process. Absorption, luminescence spectra and scintillation characteristics such as light yield, scintillation decay times, energy resolution, proportionality and afterglow were measured and compared with those of the latest LuAG:Ce single crystal and stoichiometric LuAG:Ce,Mg ceramic samples. Thanks to the elimination of oxygen vacancies produced in the vacuum sintering process, air-annealing treatment led to a significant decrease of afterglow and a remarkable enhancement of radioluminescence intensity and light yield. The highest light yield was found in annealed 1% Lu3+ rich Lu3+1%AG:Ce ceramic, reaching 14,760 ph/MeV (1 μs shaping time) and 22,400 ph/MeV (10 μs shaping time). Scintillation decays of $(Lu_{3+x}$AG:Ce ceramics consist of both fast (decay time 65–73 ns) and slow (decay time 740–1116 ns) decay components where the relative intensity of the latter is higher (~58%). A decreasing trend in scintillation efficiency was observed with increasing excess of Lu (with higher x values) in the samples. This can be explained by the existence of various electron traps due to LuAl antisite defect and structure disorder at the gain boundaries and interfaces

Towards Bright and Fast Lu3Al5O12:Ce,Mg Optical Ceramics Scintillators

The recent advent of Lu 3 Al 5 O 12 :Ce optical ceramics marks a turning point in scintillator material technology. Because of their lower preparation tem-perature, brightness, and robustness such materials can now compete with single crystals. Their further scintillation effi ciency optimization includes the thorough control of the defects responsible for optical and scintillation losses. The choice of sintering agent appears critical to achieve both high optical transparency and scintillation performance. In this work, the optical investi-gations coupled with X-ray absorption near-edge spectroscopy evidence the benefi cial role of MgO sintering agent. Mg 2+ co-dopants in ceramics drive the partial conversion of Ce 3+ to Ce 4+ . The Ce 4+ center, however, does not impair the scintillation performance due to its capability to positively infl uence the scintillation process. The importance of simultaneous application of such co-doping and annealing treatment is also demonstrated. With 0.3 at% Mg, our ceramics display a light yield of ≈25000 photons/MeV with short 1 µs shaping time, a relative fast component intensity as high as 60%, and very low afterglow. Such performances are better than those of the isostructural single crystals ever reported. We discuss the role of co-doping and annealing in the scintillation mechanism that make such combined treatments a posi-tive strategy for material engineering