Gamma-irradiation effects on Ce-doped YAG crystals grown by Cz and TGT method

Gamma-rays radiation effects on Ce:YAG crystals grown by Czochralski (Cz) and temperature gradient techniques (TGT) have been studied by means of optical absorption and luminescence spectra. Valence of Ce3+ ion changes during the gamma-ray irradiation process and this result indicates Ce4+ ion may exist in both Cz-Ce:YAG and TGT-Ce:YAG crystals. Thermally stimulated luminescence measurements reveal intense thermoluminescence peaks in gamma-irradiated Ce:YAG crystals and trap parameters were calculated by general-order kinetics expression. (C) 2006 Elsevier B.V. All rights reserved.

用Judd-Ofelt理论计算Nd^3＋掺杂氧化镧钇透明陶瓷的光谱参量

采用传统无压烧结工艺制备Nd^3 ＋掺杂的氧化镧钇透明激光陶瓷,测试了其吸收和荧光光谱.采用Judd-Ofelt理论对Nd^3 ＋掺杂量为1 .5at %的样品光谱参量进行了计算.根据吸收光谱,拟合得到三个强度参量分别为：Ω2=6 .57×10^-20cm^2,Ω4=2 .04×10^-20cm^2,Ω6=4 .38×10^-20cm^2.根据这三个参量计算了样品的辐射寿命,跃迁几率,荧光分支比,量子效率和品质因子,并对结果作了分析.

用纳米粉制备Nd：Y1.84La0.16O3透明陶瓷Nd：Y1

用碳酸盐共沉淀法制备一种新的掺钕氧化镧钇（Nd：Y1.84La0.16O3）纳米粉体,得到颗粒细小、均匀、分散性好、粒径为50～60nm的Nd：Y1.84La0.16O3纳米粉体.分别采用Nd：Y1.84La0.16O3纳米粉料和商业粉料,用传统陶瓷无压烧结工艺制备Nd：Y1.84La0.16O3透明陶瓷.Nd：Y1.8vLa0.16O3纳米粉制备的陶瓷样品的组分均匀、几乎不存在第二相,具有较高的透过率.商业粉制备的陶瓷样品因混料不均匀而在晶界处存在部分第二相,降低了陶瓷的透过率.此外,还运用体视学法预测

Yb：YAG透明陶瓷的制备和激光输出

制备了高质量的Yb：YAG透明陶瓷．Yb：YAG透明陶瓷的晶粒尺寸为10μm左右且分布均匀，晶界处和晶粒中没有杂质、气孔的存在．Yb：YAG样品中所有元素分布均匀，不同的晶粒间，晶粒和晶界间成分是一致的，没有出现成分的偏析．4mm厚样品的透过率为80％．LD泵浦获得了波长为1030nm，最大功率为268mW的连续激光输出．

Nd：YbVO4晶体的拉曼光谱和荧光光谱研究

用群论的方法计算了Nd：YbVO4晶体的拉曼活性振动模数目，在室温下测得了其极化拉曼谱线，并指认了在不同几何配置下，各振动模式所对应的频率。同时，测得了室温下晶体的吸收谱，得到了中心波长为808am吸收峰的半高宽为12nm，并在J-O理论的基础上计算了晶体的光学参数，其三个晶场参数分别为Ω2=6．88945×10^-20cm^2。Ω4=4．13394×10^-20cm^2、Ω6=4．54503×10^-20cm^2，并由此得到^4F3／2能级的荧光寿命为178．69炉，1062nm处的荧光分支比为48．85％，积分发射截面为2．786710^-18cm^2。分别在808nm、940nm激发下测得晶体室温发射谱，观察到了Nd→Yb以及Nd←Yb间的能量传递现象。

7.3 W of single-frequency output power at 2.09 μm from an Ho:YAG monolithic nonplanar ring laser

Single-frequency output power of 7.3 W at 2.09 mu m from a monolithic Ho:YAG nonplanar ring oscillator (NPRO) is demonstrated. Resonantly pumped by a Tm-doped fiber laser at 1.91 mu m, the Ho:YAG NPRO produces 71% of slope efficiency with respect to absorbed pump power and nearly diffraction-limited output with a beam quality parameter of M-2 approximate to 1.1. (c) 2008 Optical Society of America

Fabrication and spectral properties of Nd3+-doped yttrium lanthanum oxide transparent ceramics

Transparent 1 at% Nd3+:Y1.9La0.1O3 ceramics were fabricated with nanopowders prepared by carbonate coprecipitation method. The powder compacts were sintered in H-2 atmosphere at 1550 degrees C for 30 h. The Nd3+:Y1.9La0.1O3 ceramics display uniform grains of about 50 mu m and high transparency. The highest transmittance of the ceramics reaches 67%. The strongest absorption peak is in the wavelength of 820 nm with absorption cross section of 2.48 x 10(-20) cm(2). The absorption is still high at LD wavelength 806 nm with absorption cross section of 1.78 x 10(-20) cm(2) and broad full width at half maximum (FWHM) of about 6.3 nm. The strongest emission peak was centered at 1078 nm with large stimulated emission cross section of 9.63 x 10(-20) cm(2) and broad FWHM of about 7.8 nm. The broad absorption and emission bandwidth of Nd3+:y(1.9)La(0.1)O(3) transparent ceramics are favorable to achieve the miniaturized LD pumping apparatus and ultrashort modelocked pulse laser output, respectively. (c) 2007 Elsevier B.V. All rights reserved.

Growth and spectral properties of Yb,Tm:YAG crystal

The YAG crystal codoped with Yb3+ and Tm3+ has been grown by Czochralski (Cz) method. The crystal structure of the crystal has been determined by X-ray diffraction analysis. The absorption and emission spectra of Yb,Tm:YAG crystal at room temperature have also been studied. The emission cross-sections have been calculated by Fuechtbauer-Ladenburg formula and reciprocity method. (C) 2007 Elsevier B.V. All rights reserved.

Continuous-wave and passively mode-locked Yb : GYSO lasers pumped by diode lasers

We report both continuous-wave and passively mode-locked laser actions in a Yb3+-doped gadolinium yttrium oxyorthosilicate Yb:GdySiO(5) (Yb:GYSO) crystal. Continuous-wave (CW) laser operations were compared under different pump conditions with high-power diodes of different wavelengths and fiber cores. CW mode-locking was obtained with a semiconductor saturable absorber mirror.

Polarized spectral analysis of Ho3+ ions in biaxial YAlO3 crystal for 2 mu m lasers

An Ho3+-doped YAlO3 (Ho : YAP) single crystal has been grown by the Czochralski technique. The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of the crystal are measured at room temperature. The spectroscopic parameters are calculated based on Judd-Ofelt theory, and the effective phenomenological intensity parameters Omega(2,eff), Omega(4,eff) and Omega(6,eff) are obtained to be 2.89 x 10(-20), 2.92 x 10(-20) and 1.32 x 10(-20) cm(2), respectively. The room-temperature fluorescence lifetime of the Ho3+ 5I(7) -> I-5(8) transition is measured to be 8.1 ms. Values of the absorption and emission cross-sections with different polarizations are presented for the I-5(7) manifold, and the polarized gain cross-section curves are also provided and discussed.