室温下连续波运行Tm:YAP泵浦的Ho:YAG激光器

我们报道了一种以二极管泵浦的 1.94 μm Tm:YAP激光器为泵浦源，常温下在2.1 μm连续运行的Ho:YAG激光器。最大输出功率1.5 W，相应斜率效率为17.9%，二极管到的转换效率为5.6%。

Growth and its spectroscopic properties of Sm : YAP crystal

Sm3+-doped yttrium aluminum perovskite (YAP) single crystal was grown by Czochralski (CZ) method. The absorption and fluorescence spectra along the crystallographic axis b were measured at room temperature. Judd-Ofelt theory was used to calculate the intensity parameters (Omega(t)), the spontaneous emission probability, the branching ratio and the radiative lifetime of the state (4)G(5/2). The peak emission cross-sections were also estimated at 567, 607, and 648 nm wavelengths. (c) 2006 Elsevier B.V. All rights reserved.

Three-photon-excited upconversion luminescence of Ce3+: YAP crystal by femtosecond laser irradiation

Infrared to ultraviolet and visible upconversion luminescence was demonstrated in trivalent cerium doped YAlO3 crystal (Ce3+: YAP) under focused infrared femtosecond laser irradiation. The fluorescence spectra show that the upconverted luminescence comes from the 5d-4f transitions of trivalent cerium ions. The dependence of luminescence intensity of trivalent cerium on infrared pumping power reveals that the conversion of infrared radiation is dominated by three-photon excitation process. It is suggested that the simultaneous absorption of three infrared photons pumps the Ce3+ ion into upper 5d level, which quickly nonradiatively relax to lowest 5d level. Thereafter, the ions radiatively return to the ground states, leading to the characteristic emission of Ce3+. (c) 2005 Optical Society of America.

Color centers and charge state recharge in gamma-irradiated Yb : YAP

Gamma-ray irradiation induced color centers and charge state recharge of impurity and doped ion in 10 at.% Yb:YAP have been studied. The change in the additional absorption (AA) spectra is mainly related to the charge exchange of the impurity Fe2+, Fe3+ and Yb3+ ions. Two impurity color center bands at 255 and 313 nm were attributed to Fe3+ and Fe2+ ions, respectively. The broad AA band centered at 385 nm may be associated with the cation vacancies and F-type center. The transition Yb3+ -> Yb2+ takes place in the process of gamma-irradiation. Oxygen annealing and gamma-ray irradiation lead to an opposite effect on the absorption properties of the Yb:YAP crystal. In the air annealing process, the transition Fe2+ -> Fe3+ and Yb2+ -> Yb3+ take place and the color centers responsible for the 385 nm band was destroyed. (c) 2005 Elsevier B.V. All rights reserved.

YAP：Ce闪烁晶体的光致激发荧光衰减常数测量

用波长为266nm的激光激发不同尺寸、不同掺Ce^3＋浓度的YAP：Ce闪烁晶体，测量其光致激光荧光衰减常数，测量结果表明：YAP：Ce闪烁晶体的光致荧光衰减常数约为18．2ns，且与实验晶体厚度及Ce^3＋掺杂浓度（0．1％～0．6％原子分数）无关。

Spectroscopic properties of Ce : YAP scintillation crystal grown by temperature gradient technique

Spectroscopic properties of Ce-doped yttrium orthoaluminate (Ce:YAlO3 or Ce:YAP) crystals grown by temperature gradient technique (TGT) were investigated, and the effects of the growth conditions on the properties were analyzed.. Methods of optical absorption (OA), photoluminescence (PL), photoluminescence decay (PLD), X-ray excited luminescence (XL) and cathodeluminescence (CL) were used in these investigations. The results showed that the absorption band peak at 202, 394 and 532 nm originated from F and F+ color center induced by the weak reducing growth atmosphere, green emission band near 500 ran derived from Ce3+ -Ce3+ pairs and band at 650 similar to 850 run from some unintentional impurity in crystals.

室温下光纤耦合二极管泵浦Tm：YAP激光器

为实现室温下小型化、高效率的1.9μm激光输出,采用793.5 nm激光二极管泵浦Tm：YAP晶体,晶体采用热电制冷及风冷的方式控制在18℃,采用1∶1的聚焦耦系统,获得功率为2.2 W、中心波长为1928 nm的激光输出,光光转换效率为31%,斜率效率达41%。对影响激光输出的耦合输出率、腔型、腔长、晶体工作温度等因素进行了实验分析,实验结果表明：输出功率的变化与温度基本成线性关系,当增加激光谐振腔长时,由于高阶模式损耗加大以及晶体热透镜效应的加重导致腔内损耗加大,输出功率和斜率效率都有所下降。

Spectroscopic properties of Yb:YAP crystal

The 10at% Yb-YAP crystal has been grown by the Czochralski method. The absorption and emission spectra and fluorescence lifetime of Yb:YAP crystal at room temperature were studied. There is a strong absorption band centered at 959 nm and the absorption cross-section of 1.51 × 10^-20 cm². The emission cross-section at 1040 nm is 0.6 × 10^-20 cm² and the fluorescence lifetime is about 1.2 ms. The effects of O₂-annealing on the spectral properties were studied. The spectroscopic properties strongly depended on the axis direction and b axis was the best direction for laser output. The spectrum parameters of Yb:YAP and Yb:YAG crystal were compared.}

Ce：YAP晶体中的孪晶缺陷

The twin defects in Ce:YAP were investigated by using synchrotron radiation topography and etch figures. The results show that the twins are {101} and {121} types, and the exchange of neighboring lattice parameters is considered to be the intrinsic factor for twining. Based on such analysis, the twin structure model was established. Otherwise, the growth experiment results show that the abrupt change of growth rate during shoulder formation tends to cause twining.

激光二极管抽运Tm：YAP激光器获得5W连续波输出

2μm波长激光对人眼安全，在相干探测风切变、非线性频率转换等方面有重要应用。2μm波长激光还可应用到激光医疗，由于其吸收深度浅，手术精度高于发射1μm波长的激光。

高效室温下激光二极管泵浦Tm:YAP激光器

文章报道了室温下二极管泵浦Tm：YAP激光器，最大输出功率5.2瓦，波长为1981nm，斜率效率是30％。实验测量800nm左右晶体的吸收谱以及1800nm附近的荧光发射谱。此外，讨论了输出功率随晶体工作温度关系。

Yb:YAP与Yb:YAG晶体光谱性能比较

应用中频感应提拉法生长出掺杂浓度为10 at.-%的Yb:YAG与Yb:YAP晶体，对比了室温下两种晶体的吸收和发射光谱特性。结果表明，Yb:YAG晶体比Yb:YAP晶体有更好的激光性能和低的阈值；同时对比发现，Yb:YAP晶体的吸收截面是Yb:YAG晶体的2.16倍，它容易实现LD泵；由于Yb:YAP晶体的各向异性，它有轴向效应明显，它可以产生偏振激光。

国产YAP：Ce闪烁晶体的相对探测能力测量

为适应在n、γ昆合脉冲辐射场中对低强度快脉冲y辐射测量的需要，近年国内新研制出实用型YAlO3：Ce（YAP：Ce）快响应无机闪烁晶体。我们使用脉冲线性电流大于1．5A的光电倍增管，分别配置这种晶体以及CeF3、NaI等晶体构成闪烁探测器，在放射性标准源场中，对晶体的相对探测能力进行测量。测量结果表明：国产新型YAP：Ce无机晶体对这1．25MeV射线的探测能力比同体积的CeF3平均高一个量级，是同体积NaI的40％左右；当晶体厚度小于2mm时，YAP：Ce与CeF2、NaI的输出比值分别大于16和44％，说明厚度越薄晶体的相对探测能力越强。

铝酸钇晶体中的生长小面

采用提拉法生长了掺Ce、掺Yb和掺Mn的铝酸钇(YAlO3,YAP)晶体,晶体均完整透明,无肉眼可见的气泡、散射和包裹物等宏观缺陷。通过化学腐蚀和同步辐射白光形貌实验检测了YAP晶体中的生长小面缺陷。结果表明:晶体生长过程中,由于凸向熔体的固-液界面,造成了小面生长现象。沿[101]方向生长的YAP晶体中出现的小面为(102),(201),(121)和(121)奇异面。X射线摇摆曲线表征的结果表明:生长小面的存在严重破坏了晶体的微观结构完整性和均匀性,并导致了小角度晶界缺陷的产生。