Xinbo Yang

Influence of carbon on the thermoluminescence and optically stimulated luminescence of α-Al2O3:C crystals

α-Al2O3:C crystal shows excellent thermoluminescence (TL) and optically stimulated luminescence (OSL) properties but the real role carbon plays in this crystal is still not clearly understood so far. In this work, α-Al2O3:C crystal doping with different amounts of carbon were grown by the temperature gradient technique, and TL and OSL properties of as-grown crystals were investigated. Additionally, a mechanism was proposed to explain the role of carbon in forming the TL and OSL properties of α-Al2O3:C. TL and OSL intensities of as-grown crystals increase with the increasing amount of carbon doping in the crystal, but no shift is found in the glow peak location at 465 K. As the amount of carbon doping in the crystals decreases, OSL decay rate becomes faster. With the increase in heating rate, the integral TL response of as-grown crystals decreases and glow peak shifts to higher temperatures. TL response decrease rate increases with the increasing amount of carbon doping in the crystals. All the TL and OSL ...

Thermoluminescence properties of carbon doped Y3Al5O12 (YAG) crystal

In this work, carbon doped yttrium aluminum garnet (YAG) (YAG:C) crystal was grown by the temperature gradient technique in a reducing atmosphere. The optical and thermoluminescence (TL) properties of the as-grown YAG:C crystal were investigated. Four absorption bands at 235, 255, 298, and 370 nm and a main blue emission peak at 400 nm are observed in the YAG:C crystal. The absorption coefficients of the bands at 235 and 370 nm, which are associated with the F+-center, increase sharply in YAG crystal by the introduction of carbon. As-grown YAG:C crystal shows high TL sensitivity, and three main glow peaks at 390 K (P1), 465 K (P2), 524 K (P3) and two weak glow peaks at 580 and 625 K are found. The TL dose responses of the three main glow peaks show linear-supralinear characteristic, and wide linearity dose response are found in P1 and P2 glow peaks. The temperature position and TL intensity of three main glow peaks show a strong dependence of heating rate in YAG:C crystal.

Spectroscopic, Thermal, and Laser Properties of Yb:CaNb

In this paper, we report the room temperature spectroscopic and thermal properties and continuous-wave (CW) laser operation of a new Yb:CaNb2O6 crystal. The peak absorption cross section for the E||a polarization is 0.97 times 10-20 cm2 with a full-width at half-maximum of 28 nm at 975 nm. The stimulated emission cross section is 1.19 times 10-20 cm2 at 1062 nm. The thermal conductivities at room temperature are 5.40, 5.15, and 6.05 Wm-1K-1 along the a, b-, and c-axis, respectively. The fracture strength of Yb:CaNb2O6 single crystal is 315 MPa. The properties of Yb:CaNb2O6 crystal were compared with those of typical Yb-doped materials. A CW output power of 801 mW at 1062 nm was obtained with a slope efficiency of 19% by use of diode pumping.

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The effect of growth interruption on the InAs deposition and its subsequent growth as self-assembled island structures, in particular the material transport process of the InAs layers has been investigated by photoluminescence and transmission electron microscopy measurements. InAs material in structures with only coherent islands transfers from the wetting layer to the formed islands and the growth interruption causes a red shift of PL peak energy. On the other hand, the PL peak shifts to higher energy in structures containing simultaneously coherent and noncoherent islands with dislocations. In this case, the noncoherent islands capture InAs material from the surrounding wetting layer as well as coherent islands, which casues a reduction in the size of these islands. The variations in the PL intensity and line width are also discussed

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Carbon doped YAG (YAGu2009:u2009C) crystal is designed and grown by the temperature gradient technique, and the optical and optically stimulated luminescence (OSL) properties of the as-grown crystal are investigated. High concentration F+-centres with an emission at 400u2009nm are produced in the YAG crystal by the introduction of carbon. The as-grown YAGu2009:u2009C shows high OSL sensitivity and excellent OSL response thermal stability up to 573u2009K. In the wide dose range from 0.1 to 50u2009Gy, the OSL response shows excellent linearity, and saturation is found at about 200u2009Gy. Almost no light-induced fading is observed in the YAGu2009:u2009C crystal when exposed in the dark.