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121.
Rear-surface light intensification caused by Hertzian-conical crack in 355-nm silica optics 下载免费PDF全文
Theoretical studies show that the Hertzian-conical crack can be considered to be composed of double cone faces for simplification. In the present study, the three-dimensional finite-difference time-domain method is employed to quantify the electric-field distribution within the subsurface in the presence of such a defect under the normal incidence irradiation. Both impurities (inside the crack) and the chemical etching have been investigated. The results show that the maximum electric field amplitude |E| max is 9.57374 V/m when the relative dielectric constant of transparent impurity equals 8.5. And the near-field modulation will be improved if the crack filled with remainder polishing powders or water vapor/drops. Meanwhile, the laser-induced initial damage is moving to the glass-air surface. In the etched section, the magnitude of intensification is strongly dependent on the inclination angle θ. There will be a highest modulation when θ is around π /6, and the maximum value of |E| max is 18.57314 V/m. When θ ranges from π /8 to π /4, the light intensity enhancement factor can easily be larger than 100, and the modulation follows a decreasing trend. On the other hand, the modulation curves become smooth when θ > π /4 or θ < π /8. 相似文献
122.
Numerical simulation of the modulation to incident laser by the repaired damage site in a fused silica subsurface 下载免费PDF全文
One of the main factors of laser induced damage is the modulation to incident laser which is caused by the defect in the subsurface of the fused silica.In this work,the repaired damage site irradiated by CO 2 laser is simplified to a Gaussian rotation according to the corresponding experimental results.Then,the three-dimensional finite-difference time-domain method is employed to simulate the electric field intensity distribution in the vicinity of this kind of defect in fused silica front subsurface.The simulated results show that the modulation is notable,the E max is about 2.6 times the irradiated electric field intensity in the fused silica with the damage site (the width is 1.5 μm and depth is 2.3 μm) though the damage site is repaired by CO 2 laser.The phenomenon and the theoretical result of the annular laser enhancement existed on the rear surface are first verified effectively,which agrees well with the corresponding experimental results.The relations between the maximal electric field intensity in fused silica with defect depth and width are given respectively.Meanwhile,the corresponding physical mechanism is analysed theoretically in detail. 相似文献
123.
The microstructure,optical property and magnetism of nitrogen ion implanted single MgO crystals are studied. A parallel investigation is also performed in an iron ion implanted single MgO sample as a reference. Large structural,optical and magnetic differences are obtained between the nitrogen and iron implanted samples. Room temperature ferromagnetism with a fairly large coercivity field of 300 Oe (1Oe=79.5775 A/m),a remanence of 38% and a slightly changed optical absorption is obtained in the sample implanted using nitrogen with a dose of 1×1018 ions/cm2 . Tran- sition metal contamination and defects induced magnetism can be excluded when compared with those of the iron ion implanted sample,and the nitrogen doping is considered to be the main origin of ferromagnetism. 相似文献
124.
125.
FAAS测定十味平性活血化淤中药中Fe、Cu、Zn、Mn的含量 总被引:1,自引:0,他引:1
为揭示中药药性本质,用FAAS测定并比较了十味平性活血化淤中药中微量元素Fe、Cu、Zn和Mn的含量。结果表明,十味活血化淤中药均含有Fe、Cu、Zn、Mn等4种元素,其中Fe、Cu、Zn、Mn的含量范围分别为0.0416~1.2977,0.0025—0.0297,0.2100~0.1501,0.0071~0.7380μg·g^-1。方法加标回收率为98.7%~100.5%,RSD≤2.45%(n=6)。实验方法简便可行,测定结果准确可靠,为后续研究提供了基础数据。 相似文献
126.
127.
熔石英亚表面划痕对入射激光的调制是导致光学材料损伤的主要因素.本文建立了熔石英后表面上三维Hertz锥形划痕模型,采用三维时域有限差分方法对划痕周围的电场强度进行了计算模拟,并分别讨论了划痕的深度、半径以及倾斜角度对入射光场调制作用的影响.结果表明:Hertz锥形划痕中心区域的电场增强效果最明显,最容易被辐照损伤;划痕的深度从λ变化到9.5λ的过程中,熔石英内的最大电场强度逐渐增大;半径小于15λ的Hertz锥形划痕较容易引起熔石英的损伤,当半径大于175λ时,熔石英内的最大电场强度都维持在2.5 V/m,不再受半径大小影响;当入射激光在划痕的内侧界面和熔石英后表面之间发生内全反射时,光场增强效果愈加明显.
关键词:
三维时域有限差分
Hertz锥形划痕
电场分布
数值模拟 相似文献
128.
室温下采用640nm的飞秒脉冲激光泵浦ZnO纳米针得到双光子诱导的光致发光谱。结合单光子下的研究结果,实验分析了双光子泵浦下样品随着受激能量增强产生的三种紫外发射行为并归结为自由激子自发辐射,激子-激子散射和电子空穴等离子体复合。双光子泵浦下ZnO纳米针的受激阈值是4.82GW/cm2,远小于其他ZnO微纳材料的双光子阈值(TW/cm2)。结果表明:这种新型的ZnO纳米针结构能更有效地产生双光子激射,这在纳米激光器方面将会有很大的应用前景。 相似文献
129.
由于某大型激光原型装置内爆实验的燃料面密度很低,提出了利用充纯D燃料内爆产生的初级DD中子和次级DT中子的产额比值来诊断燃料面密度的方法。在该原型装置的首轮内爆实验中,利用研制的高灵敏塑料闪烁体探测器对初级DD中子产额和次级DT中子产额进行了测量。通过实验发现,当初级DD中子产额高于108时,可以测得次级DT中子实验数据。建立了均匀内爆模型,用初级和次级中子产额比值法对燃料面密度进行计算,获得的该原型装置首轮内爆实验燃料压缩的平均面密度小于4.0 mg/cm2。 相似文献
130.
Optical and structural properties of Ge-ion-implanted fused silica after annealing in different ambient conditions 下载免费PDF全文
Ge+ ions are implanted into fused silica glass at room temperature and a fluence of 1×10 17 cm-2 . The as-implanted samples are annealed in O2, N2 and Ar atmospheres separately. Ge0 , GeO and GeO2 coexist in the as-implanted and annealed samples. Annealing in different atmospheres at 600℃ leads each composite to change its content. After annealing at 1000℃, there remains some amount of Ge 0 in the substrates. However, the content of Ge decreases due to out-diffusion. After annealing in N2 , Si–N composite is formed. The absorption peak of GeO appears at 240 nm after annealing in O2 atmosphere, and a new absorption peak occurs at 418 nm after annealing in N2 atmosphere, which is attributed to the Si–N composite. There is no absorption peak appearing after annealing in Ar atmosphere. Transmission electron microscopic images confirm the formation of Ge nanoparticles in the as-implanted sample and GeO 2 nanoparticles in the annealed sample. In the present study, the GeO content and the GeO2 content depend on annealing temperature and atmosphere. Three photoluminescence emission band peaks at 290, 385 and 415 nm appear after ion implantation and they become strong with the increase of annealing temperature below 700℃, and their photoluminescences recover to the values of as-grown samples after annealing at 700℃. Optical absorption and photoluminescence depend on the annealing temperature and atmosphere. 相似文献