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在室温下,测量了采用Czochralski方法生长的as-grown和经退火处理的Z切Er^3+/Yb^3+共掺同成分LiNbO3晶体的α偏振吸收光谱(300-1650nm)。运用Judd—Ofelt理论对该晶体中Er^3+的光谱特性进行了分析。由所测得的吸收系数的积分计算得到了从基态到激发态的若干个主要的电子跃迁强度实验值。利用最小二乘法确定出Er^3+/Yb^3+共掺LiNbO3晶体中Er^3+的Judd-Ofelt参数。进而确定了自发辐射概率,从激发态能级到其各个下能级的荧光分支比以及能级辐射寿命。此外,还讨论了Yb^3+的共掺和退火处理对LiNbO3晶体中Er^3+光谱特性的影响。 相似文献
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Yu-Jing Yang 《中国物理 B》2022,31(3):34201-034201
We systematically investigate the power distribution characteristics of microjets generated by prismatic scatterers with different shapes at sub-THz region (λ = 8.57 mm). Among these prismatic scatterers, the hexagonal-type one shows better focusing feature than the others. Aiming at the hexagonal-type one, we propose a double-layer scatterer composed of a Teflon hexagonal prism as an outer layer and a semiconductor cuboid as an inner layer. Aiming at the double-layer scatterer, we further study the effects of refractive index, size, and shape of the inner cuboid on microjet's features. The study allows us to present an optimized double-layer scatterer, which has a side length λ /2 (λ) and a refractive index 2.0 (1.4) for the inner (outer) layer. We show that the optimized scatterer can produce an ultra-strong, ultra-narrow microjet with a power enhancement of ~30 and a full width at half maximum (FWHM) of ~0.26λ, and the microjet is just located at the output face. The microjet keeps compact within the distance range of λ from the output face. These features and effects are explained from the viewpoint of ray optics theory. According to the optimized double-layer scatterer, we further study the multi-frequency focusing features of the microjets, and find that the microjet remains good features at harmonic frequencies 2f0 and 3f0. In addition, we investigate the effect of an Au sphere presence in the center of the microjet on the power distribution. The results show that a spherical dark spot with a size similar to that of the Au sphere emerges in the area where the Au sphere is placed. The feature can be used to measure the size of a metallic particle. 相似文献