Showing papers by "Xinbo Yang published in 2009"

Thermoluminescence properties of carbon doped Y3Al5O12 (YAG) crystal

Abstract: 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.

Crystal growth, spectral and laser properties of Yb3+:NaGd(WO4)2 crystal

Abstract: Yb3+-doped NaGd(WO4)2 (Yb:NGW) crystal has been successfully grown by Czochralski method. The rocking curves from (400) plane of as-grown Yb:NGW crystal was measured and the full-width values at half-maximum was 21″. The polarized absorption spectra, the fluorescence spectra and the fluorescence decay lifetime of Yb:NGW crystal were measured at room temperature. The spectroscopic parameters of Yb:NGW crystal are calculated and compared, with those of Yb:YAG crystal. A continuous wave output power of 3.01 W at 1048 nm was obtained with a slope efficiency of 71% by use of diode pumping.

Spectroscopic, Thermal, and Laser Properties of Yb:CaNb $_{2}$ O $_{6}$ Crystal

Abstract: 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.

Crystal growth, optical properties, and laser operation of Yb3+-doped NYW single crystal

Abstract: Laser crystal Yb3+-doped NaY(WO4)2 (Yb:NYW) with excellent quality has been grown by Czochralski technique. The rocking curves from (400) plane of as-grown Yb:NYW crystal was measured and the full-width value at half-maximum was 19.92″. The effective segregation coefficients were measured by the X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Yb:NYW crystal were measured at room temperature. The fluorescence decay lifetime of Yb3+ ion in NYW crystal has been investigated. The spectroscopic parameters of Yb:NYW crystal are calculated and compared with those of Yb:YAG crystal. A continuous wave output power of 3.06 W at 1031 nm was obtained with a slope efficiency of 42% by use of diode pumping.

The optically stimulated luminescence of carbon doped Y3Al5O12 (YAG) crystal

Abstract: Carbon doped YAG (YAG : C) 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 400 nm are produced in the YAG crystal by the introduction of carbon. The as-grown YAG : C shows high OSL sensitivity and excellent OSL response thermal stability up to 573 K. In the wide dose range from 0.1 to 50 Gy, the OSL response shows excellent linearity, and saturation is found at about 200 Gy. Almost no light-induced fading is observed in the YAG : C crystal when exposed in the dark.

Influence of Pulling Rates on the Thermoluminescence and Optically Stimulated Luminescence of α‐Al2O3:C Crystals Grown by the Edge‐Defined, Film‐Fed Growth Technique

Abstract: In this work, α-Al 2 O 3 :C crystals were grown by the edge-defined, film-fed growth method with different pulling rates. The influence of pulling rate on the optical, thermoluminescence (TL), and optically stimulated luminescence (OSL) properties of the as-grown α-Al 2 O 3 :C crystals was investigated. All the α-Al 2 O 3 :C crystals grown with different pulling rates show a single TL glow peak and an invariable blue emission band at 415 nm. With an increasing pulling rate in the 0.1-0.7 mm/min range, the absorption coefficient of optical absorption bands at 206 and 256 nm increased, the TL and OSL dose response improved, the TL peak shifted to higher temperatures, and the OSL decay rate increased. When the pulling rate is increased to 1 mm/min, the absorption coefficients of the bands at 206 and 256 nm, the TL temperature and intensity, the OSL intensity, and the decay rate declined. The TL and OSL dose response of the as-grown α-Al 2 O 3 :C crystals shows a linear-sublinear saturation characteristic. The pulling rates almost show no influence on the crystals' saturation dose. The α-Al 2 O 3 :C crystal grown with the pulling rate of 0.7 mm/min shows the best TL and OSL properties.