177 resultados para orientamento :: 365 :: Geoingegneria
Resumo:
文中报道了一台采用激光二极管部分边缘泵浦方式的高功率薄片激光器,晶体尺寸是1 mm×10 mm×60 mm。Cr4+:YAG被用来作为被动调Q晶体,在重复频率高于10kHz时,获得了脉宽10ns,平均功率70W,斜线效率为36\%的激光输出。通过控制泵浦光束直径的大小,我们在厚度方向得到了近似衍射极限的光束输出。整个激光器结构紧凑,大小为60 mm×174 mm×150 mm。
Resumo:
设计了组成为0.70TeO2-(0.20-x)ZnO-xGeO2—0.05La2O3-0.025K2O-0.025Na2O-0.01Yb2O3(摩尔分数x=0,0.05,0.10,0.15和0.20)的碲酸盐激光玻璃,测试了热学性质、吸收光谱、荧光光谱和荧光寿命。计算了Yb^3+离子的吸收截面、受激发射截面、荧光有效线宽等参数。结果表明,组成为0.70TeO2-0.20GeO2-0.05La2O3-0.025K2O-0.025Na2O的玻璃具有优于著名的碲锌钠(TZN)玻璃的热稳定性,高的受激发射截面(1
Resumo:
In this paper, we present results on upconversion luminescence performed on Yb3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%. (c) 2004 Elsevier B.V. All rights reserved.
Resumo:
We report on photoreduction of Ag+ in aluminoborate glasses induced by irradiation of a femtosecond laser. Novel fluorescence was observed in the femtosecond laser irradiated glass when excited by a 365 nm ultraviolet lamp. Optical absorption, emission, and electron spin resonance spectra of the glass samples demonstrated that after the laser irradiation, portions of silver ions near the focused part of the laser beam inside the glass were reduced to silver atoms, which resulted in the formation of the characteristic fluorescence. The observed phenomenon may have promising applications in the fabrication of functional optical devices.