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分布耦合系数对线性啁啾光栅色散的影响 总被引:6,自引:1,他引:6
本文从光栅反向耦合波方程出发,经相位共轭变换用Runge-Kuta-Gil方法对其数值求解。针对线性啁啾光栅耦合系数变化服从不同的分布,分析了各种分布对光栅反射谱特性和色散特性的影响。 相似文献
206.
Pinning effect of lead lanthanum titanate (PLT) ferroelectric thin films with excess PbO of 20 mol% has been studied for deposition on diffe rent substrates. Silicon, sapphire and quartz were used as substrates on which P t/Ti or LaNiO3 thin films were deposited as bottom electrodes. Electron probe analysis results showed that there was still a certain amount of excess Pb in PLT films after annealing at 550 ℃ for 1 h, and the amount of it was dependent on the substrate used. The distribution of excess Pb in the films was investig ated by Auger electron spectroscopy depth profile. It was shown that the substrates and the bottom electrodes had significant effects on the content and distrib ution of excess Pb in PLT films. The excess Pb and its accumulation at the inter face between the film and bottom electrode may act as pinning centers and have a pinning effect on domains, which can be observed by abnormal P-E hysteresis loops and abnormal C-V curves. The excess Pb content in the films and the accumulation of Pb at the interface were high in PLT films deposited on Pt/Ti/S i, and considerable pinning effect was observed. As LaNiO3 would absorb most part of the excess Pb in PLT films, the content of excess Pb in the films deposited on LaNiO3/Si was very low and the pinning effect was hardly observed. 相似文献
207.
We explore some possible mechanisms by which the heavy neutral cosmic particles are accelerated to gain sufficiently high kinetic energies and cause observable effects at detectors on the earth. Our results indicate that all the known sources which are based on the established theories and observations fail to give rise to very high energy with sizable flux intensity. If the heavy neutral particles of kinetic energies of GeV order indeed exist in cosmic rays, there must be certain mechanisms beyond our present knowledge of dark matter and universe evolution. 相似文献
208.
REN Hongwu FANG Zhujie 《Chinese Journal of Lasers》1999,8(6):525-530
1 Introduction Opticaltomographyprovidesanalternativetechnologytoprobebreastcancerandmonitorhumantissue’sfunctionalparameternoninvasively[1,2].Photonmigrationintissueplaysakeyroleinopticaltomography.Recently,alatticerandomwalkmodel[3,4]isemployedtod… 相似文献
209.
本文用岛津ICPQ-1000型光谱仪,并且使用了HG-3B氢化物发生器,这种发生器利用ICP载气的压力产生的负压,自动吸入试样和NaBH4溶液并发生氢化反应,生成的气态氢化物进入ICP火炬并被激发。使用这种氢化物发生器同时测定了As,Sb,Se,Bi等4种元素,其检出限与常规气动喷雾器在比较至少降低了一个数量级。 相似文献
210.
Using a recently developed new scheme, we investigated the electronic structure of the lowest conduction band states of cuboid GaAs quantum dots with different shapes and sizes in a wide range from 4 to 120a (a is the lattice constant). The critical edge length of the direct/indirect crossover in GaAs cuboid quantum dots depends on the size and shape of the quantum dots. As a deduction we also discussed the critical size of dlrect/indirect transition in GaAs quantum wires and thin films. 相似文献