Effect of native defects and laser-induced defects on multi-shot laser-induced damage in multilayer mirrors

The roles of laser-induced defects and native defects in multilayer mirrors under multi-shot irradiation condition are investigated. The HfO 2 /SiO 2 dielectric mirrors are deposited by electron beam evaporation(EBE) . Laser damage testing is carried out on both the 1-on-1 and S-on-1 regimes using 355-nm pulsed laser at a duration of 8 ns. It is found that the single-shot laser-induced damage threshold(LIDT) is much higher than the multi-shot LIDT. In the multi-shot mode,the main factor influencing LIDT is the accumulation of irreversible laser-induced defects and native defects. The surface morphologies of the samples are observed by optical microscopy. Moreover,the number of laser-induced defects affects the damage probability of the samples. A correlative model based on critical conduction band(CB) electron density(ED) is presented to simulate the multi-shot damage behavior.     

Analysis of ultra-broadband high-energy optical parametric chirped pulse amplifier based on YCOB crystal

A new type of optical parametric chirped pulse amplifier is designed and analyzed for the amplification of pulse centered at 808 nm.A novel crystal,yttrium calcium oxyborate YCa4O(BO3)3(YCOB),is utilized in the power amplification stage of optical parametric amplification(OPA).Noncollinear phase matching parameters in the xoz principle plane of YCOB,compared with those in BBO and DKDP,are analyzed by numerical simulation.The results show that YCOB rather than DKDP can be used in the power amplification stage of OPA to realize the amplification of chirped pulse to several joules with a gain bandwidth exceeding 100 nm.This can be used to gain a high intensity pulse of ～10 fs after the compressor.     

风沙稳定输运中起跳沙粒运动状态分布函数

本文用气固二相流模型模拟了风沙稳定输运过程。若起跳沙粒运动状态分布函数采用由实验得到的正态分布函数形式时,计算出的水平质量流量通量随高度的变化规律与实验结果不同。经深入分析,本文提出一新的起跳沙粒运动状态分布函数形式。其中初始起跳角的分布仍采用正态分布函数形式,而对初始起跳速度则采用指数函数和正态分布函数的分段函数形式。计算结果表明本文提出的起跳沙粒运动状态分布函数与实际情况吻合较好。     

Inequalities For Electron Repulsion Integrals

We derive a number of inequalities which must be satisfied by the interelectron repulsion integral occurring in quantum mechanical calculations. These inequalities are valide for any type of basis functions or orbitals. They can be useful in testing computer programs which evaluate these integrals. Integral approximations used in semi-empirical methods should be consistent with these inequalities.