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A Nd3+ doped La3Ga5.5Ta0.5O14 (Nd:LGT) crystal has been grown by the Czochralski method for the first time. Absorption spectrum and fluorescence spectrum has been measured and the results show Nd:LGT crystal may emit 1064 nm wavelength laser when a laser-diode of 808 nm is used as pumping source. The laser experiment indicates the output power of Nd:LGT is 130 mW when the incident pumping power is 2.2 W. [Copyright &y& Elsevier]

To precisely characterize the defects in crystalline solids including semiconductors and alloys, it is critical but challenging to improve the time resolution of positron annihilation lifetime (PAL) spectrometers. The effects of geometry and wrapping of scintillators on the time resolution of the PAL spectrometer were studied in detail. Geant4 program simulation was used to clarify the reason why cone-frustum-shaped scintillators have better time resolution than cylinder-shaped scintillators. A figure of merit was proposed to comprehensively evaluate the impacts of the transport and absorption of fluorescent photons on the time resolution of scintillators. Additionally, for the simulations of cone-frustum-shaped scintillators, polished reflective coatings can further improve the time resolution without losing count rate. Eventually, using three cone-frustum-shaped Ba F 2 scintillators and a double-stop setup, we significantly improved the time resolution of PAL spectrometer to a new record of 88.7 ps, the best time resolution up to date. This enables us to distinguish various vacancy types in crystalline solids more precisely in future. • Explained why cone-frustum-shaped scintillators have better time resolution. • Proposed a figure of merit to evaluate the time resolution of PAL spectrometer. • Achieved the best time resolution up to date for the PAL spectrometer. [ABSTRACT FROM AUTHOR]

Abstract: This investigation witnesses the fact that the direction of the light-induced self-diffraction spot changes with different Ca2+-doped CSBN ((Ca0.28Ba0.72) x (Sr0.60Ba0.40)1−x Nb2O6) crystals, indicating that the formed noise-grating wave vector direction changes with different ion-doped. Based on the wave optics theory and light-induced self-diffraction under the incident of plane monochromatic light wave in CSBN crystals, the theoretical model of noise-grating is analyzed, constructed and validated in this work. [Copyright &y& Elsevier]

Abstract: A passively Q-switched all solid-state Nd:LuVO4 1.06μm laser was demonstrated by using Cr4+:YAG as saturable absorber. The characteristics of average output power, pulse width, repetition rate, pulse energy, and peak power were studied with different output couplings and initial transmission of saturable absorbers. When output coupling with the transmission of 20% was used, the shortest pulse width of 16ns at the repetition rate of 12.5kHz was obtained, which results in the pulse energy of 71μJ and peak power of 4.43kW with the initial transmission of 70% of Cr4+:YAG crystal. [Copyright &y& Elsevier]

Abstract: New data relating to flux growth, composition, homogeneity and physical characteristics of (R,Y)Al3(BO3)4 (R=Tm or Yb) crystals are discussed. Single crystals have been obtained using K2Mo3O10-based fluxes by spontaneous nucleation as well as by the top-seeded solution growth at cooling rates of 4.8–12°C/day and 0.2–5°C/day, respectively, in the temperature range from 1120 to 900°C. It is found that the average Tm and Yb segregation coefficients are close to unity, and vary from 0.80 to 1.02, as a consequence of minor difference in the sizes between Y3+ and R3+ cations. Two morphological types of (Tm,Y)Al3(BO3)4 crystals have been revealed. The average thermal expansion coefficients of Yb:YAB along a- and c-axis are measured as 2×10−6/K and 9.7×10−6/K, respectively, in the temperature range of 298–573K. The specific heat of the Yb:YAB crystal at room temperature is found to be 0.76J/gK, implying that this material can exhibit significant resistance to laser damage. Over 1.1W of green emission has been obtained from a diode pumped 3×3×3mm3 Yb:YAB crystal. The conversion efficiency of diode to green is 10%. High beam quality of green and IR emission can be easily attained due to the good crystal quality and lack of thermal effects. [Copyright &y& Elsevier]

High purity KTiOPO4 (KTP) crystals have been grown using a flux method. The quality, SHG efficiency and damage threshold of KTP crystals grown from high purity reagents were compared with those grown from commercial reagents. Experimental results indicate that KTP crystals using a high purity charge contain less impurities and possess higher SHG efficiency and damage threshold than do crystals grown from commercial reagents. It is proposed that decreasing the concentrations of impurities is an effective way of raising the damage threshold for KTP crystals. [Copyright &y& Elsevier]

Large NdP 5 O 14 crystal with dimension of 15 × 25 × 60 mm 3 has been grown by flux method. The spontaneous strains and ferroelastic domain structures have been investigated by high resolution X-ray diffractometry for the first time. The reflection peak separations resulting from the misorientation between matrix domain and ferroelastic domain were observed in the rocking curves for several different reflections. Based on the features of the reflection peak separations, the ferroelastic domain structures were determined. It is found that most of the ferroelastic domains in NdP 5 O 14 are of type-a, while type-b ferroelastic domains only appear in the serious strain regions. Based on the domain structures of NdP 5 O 14 , the reflection peak separations for 802, 402 and 204 reflections were calculated respectively. And the experimental observations are in agreement with the calculations very well. In addition, the spontaneous strain in NdP 5 O 14 was determined to be 0.0082 by measuring the peak separation between two 800 diffraction from the matrix domain and the ferroelastic domain respectively. A detailed discussion on domain structures in the crystal is given in terms of structural and symmetric analyses. [ABSTRACT FROM AUTHOR]

By using metal nitrates as starting materials and citric acid as complexing agent, Y3Al5O12 (YAG) and Y3Al5O12:Eu (1 mol%) (YAG:Eu) powder phosphors were prepared by a citrate–gel method. The formation process of YAG and YAG:Eu were investigated by means of XRD, TG–DTA and FT-IR spectra. The purified crystalline phases of YAG and YAG:Eu were obtained at 800 °C. The crystalline YAG:Eu phosphors showed an orange–red emission with 5D0–7F1 (591 nm) as the most prominent group, whose intensity was dependent on the pH value of the starting solution, citric acid content and firing temperature. It has been found that the suitable pH and citric acid/metal ratio are 3 and 2 for obtaining the highest emission intensity, respectively. The emission intensity increases steadily with increasing the annealing temperature from 800 to 1200 °C, and nearly remains constant after 1200 °C. Furthermore, great differences were observed for the lifetimes and the charge transfer band of Eu3+ in crystalline and amorphous states of YAG. [Copyright &y& Elsevier]

Abstract. A comparative study of Nd:GdVO[sub 4] and Nd:YVO[sub 4] crystal lasers pumped by a cw diode laser has been conducted at the fundamental wavelengths of 1.06 micro m and 1.34 micro m, as well as when intracavity frequency-doubled to 532 nm and 670 nm, respectively. At these four wavelengths, maximum output powers from the Nd:GdVO[sub 4] crystal laser were 1.27 W, 800mW, 610mW, and 82mW at a diode-launched pump power of 2.9 W. The threshold pump powers were 64 mW, 159 mW, 5 mW, and 12 mW, respectively. All the results obtained from Nd:GdVO[sub 4] were superior to those of Nd:YVO[sub 4], indicating that Nd:GdVO[sub 4] is a more efficient laser crystal than Nd:YVO[sub 4] for diode-pumped solid-state lasers. [ABSTRACT FROM AUTHOR]