Feng Xiqi

Comparison of Nd:YAG Ceramic Laser Pumped at 885 nm and 808 nm

Laser performance of 1064 nm domestic Nd:YAG ceramic lasers for 885 nm direct pumping and 808 nm traditional pumping are compared. Higher slope efficiency of 34% and maximum output power of 16.5 W are obtained for the 885 nm pump with a 6 mm length 1 at.% Nd:YAG ceramic. The advantages for 885 nm direct pumping are discussed in detail. This pumping scheme for highly doping a Nd:YAG ceramic laser is considered as an available way to generate high power and good beam quality simultaneously.

Influence of Sb on the Scintillation Properties of Lead Tungstate Crystal

Sb-doped lead tungstate (PWO) crystals were grown and investigated. The measurements of Sb content in crystals indicated that the segregation coefficient of Sb in PWO is about 0.63. Even with a little Sb3+ introduced into PWO crystal, the transmission, especially the light yield was enhanced significantly. Furthermore, after the Sb-doped PWO crystals were annealed, not only the fast component still remained a high percentage but also the radiation hardness was improved evidently. The main reason may be that Sb-doping can compensate the composition deficiency and then reduce the density of hole centers such as Pb3+ and O-.

高光输出快衰减Pr: Lu 3 Al 5 O 12 闪烁陶瓷的制备和成像

采用真空烧结固相反应法, 分别制备了不添加和添加烧结助剂(正硅酸乙酯TEOS和MgO)的Pr:LuAG ( Pr: Lu 3 Al 5 O 12 )陶瓷, 研究发现添加烧结助剂烧制的Pr:LuAG陶瓷在可见光区的直线透过率可达～80%, 不添加烧结助剂的陶瓷光学透过率降低(可见光区~70%, 2 mm厚), 但光输出提高了5倍(为1196 pe/MeV), 衰减快分量比例可达73%, 能量分辨率8.4%。将Pr:LuAG陶瓷加工成1.9 mm×1.9 mm×1.0 mm的陶瓷阵列组装探测器模块, 用4×4陶瓷阵列单元实现了二维散点图成像, 所成散点图清晰可辨。经过平台测试, 相同耦合条件下本实验制备的Pr:LuAG陶瓷成像质量优于商用BGO (Bi 4 Ge 3 O 12 )单晶, 结果显示Pr:LuAG陶瓷有望应用于PET (Positron Emission Tomography) 级别核医学成像系统。采用真空烧结固相反应法, 分别制备了不添加和添加烧结助剂(正硅酸乙酯TEOS和MgO)的Pr:LuAG ( Pr: Lu 3 Al 5 O 12 )陶瓷, 研究发现添加烧结助剂烧制的Pr:LuAG陶瓷在可见光区的直线透过率可达～80%, 不添加烧结助剂的陶瓷光学透过率降低(可见光区~70%, 2 mm厚), 但光输出提高了5倍(为1196 pe/MeV), 衰减快分量比例可达73%, 能量分辨率8.4%。将Pr:LuAG陶瓷加工成1.9 mm×1.9 mm×1.0 mm的陶瓷阵列组装探测器模块, 用4×4陶瓷阵列单元实现了二维散点图成像, 所成散点图清晰可辨。经过平台测试, 相同耦合条件下本实验制备的Pr:LuAG陶瓷成像质量优于商用BGO (Bi 4 Ge 3 O 12 )单晶, 结果显示Pr:LuAG陶瓷有望应用于PET (Positron Emission Tomography) 级别核医学成像系统。Pr:LuAG ceramics were fabricated by a solid state reaction method using vacuum sintering with or without sintering aids (TEOS and MgO). The inline transmittance of the Pr:LuAG ceramics sintered with sintering aids reached similar to 80% in visible light range, while the ceramics without sintering aids were 5 times higher light output (1196 pe/MeV) and faster decay (73% fast decay component) although lower transmittance in visible light region (similar to 70%, 2.0 mm thick) comparatively with the energy resolution of 8.4%. The Pr:LuAG cermics were cut and polished to 1.9 mm x1.9 mm x 1.0 mm pixels to form ceramics arrays, by using the 4x4 ceramics arrays, 2D mapping was accomplished. The position signals were clearly identified, which were better than that of commercial BGO (Bi4Ge3O12) crystals. It is proved that Pr:LuAG ceramics is promising in PET (Positron Emission Tomography) imaging.

Investigation on the scattering effect of ceramic Nd:YAG

This paper investigates the scattering effect of domestic 0.5 at % ceramic Nd:YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave (CW) Nd:YAG ceramic laser was also demonstrated. A maximum output power of 6.7 W at 1064 nm was obtained at an 808-nm pump power of 32.9 W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd:YAG.

Photocurrent decay and thermoluminesence of doped Bi4Ge3O12

Abstract In this paper, we prsent photocurrent decay and thermoluminesence(TL) in the Bi4Ge3O12(BGO) crystals dopped with Fe, Mn, Pb, W and Ce. The photocurrents are enhanced by the Ultra-violet(UV) light. Data of the TL and the decay of the photocurrent reveals different traps in samples.