共查询到20条相似文献,搜索用时 62 毫秒
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在由矢量衍射理论得到的锥面衍射情形下的广义光栅方程基础上,给出了对应于衍射极角的衍射光栅第一类角色散公式和对应于衍射方位角的衍射光栅第二类角色散公式,并通过理论和数值分析导出了第二类角色散发生突变的条件及相应的数学表达式.
关键词:
衍射光栅
锥面衍射
第一类角色散
第二类角色散 相似文献
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在矢量衍射理论基础上给出了任意入射状态下二维平面光栅的光栅方 程,推导出二维平面光栅角色散公式的完整解析形式,确立了二维平面光栅衍射极角 角色散(第一类角色散)和衍射方位角角色散(第二类角色散)的概念. 通过二维平面光栅 衍射极角和衍射方位角角色散的理论分析和数值计算,阐明了当入射波矢偏离光栅法线时, 衍射光斑阵列发生畸变的机理,并明确指出了引起衍射方位角角色散的突变、导致衍射光斑 阵列剧烈变化的条件,因而具有理论上的意义. 在实际应用方面,以晶体和量子点 的x射线衍射、低能电子衍射和反射式高能电子衍射为
关键词:
二维平面光栅
衍射极角角色散
衍射方位角角色散
晶体电子衍射 相似文献
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位相畸变光束的聚焦特性与光束质量 总被引:5,自引:0,他引:5
针对高斯型随机位相畸变,应用夫琅和费衍射积分研究了畸变光束的聚焦特性和光束质量M^2因子,给出子它们随位相畸变特征量主烨的近似分析和数计算结果,可为高功率激光器的设计提供理论依据。 相似文献
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宽带光打靶可以有效降低激光等离子体相互作用过程中非线性效应。提出一种基于角色散的非共线匹配宽带三倍频方案,利用宽带基频与窄带二倍频的非共线和频产生宽带三倍频,和频过程中通过特殊设计的渐变光栅实现不同频率的基频光束以特定角度入射,补偿了波长差异引入的位相失配使得全波段满足位相匹配条件。理论模拟表明,采用KDP晶体Ⅱ类位相匹配,将中心波长为1058 nm、带宽10 nm的宽带基频光与526.5 nm的二倍频光进行非共线匹配和频,可以实现高效宽带三倍频转换。 相似文献
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对用分光计测定光栅常数为1/300 mm透射光栅1级角色散的方法进行了改进,给出了引入自组光具组进行测量的方法.改进后的方法充分利用自组光具组基本特性参数在较大范围内连续可调的优点,克服传统的用分光计测量方法中光路的关键参数不可调节的不足,从而提高了测量精度.自组光具组的引入,也起到使光路参数选取具有多样性和丰富光路调... 相似文献
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考虑光束的发散、光栅角色散以及光栅制作过程中存在的刻槽倾角误差,应用光线追迹方法,建立了激光束入射到光栅时相位变化的计算模型。利用衍射积分方法和光束非相干叠加原理,推导出阵列光源各子光束经谱合成系统后合成光束的光强分布解析表达式。在此基础上,利用强度二阶矩方法,计算了合成光束的M2因子,并定量分析了光栅角色散和光栅刻槽倾角误差对谱合成光束特性的影响。研究结果表明:光栅角色散和光栅刻槽倾角误差的存在均会导致谱合成光束的光束质量变差,光栅刻槽倾角误差的影响比光栅角色散的影响更为明显。 相似文献
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主要介绍了一种对位相畸变光倍频的描述方法,具体从统计光学观点出发,针对高斯型随机位相畸变,在薄晶体近似下,分析位相畸变光束的倍频转换过程,给出了基波、倍频波随位相畸变特征量变化的理论模型和数值计算结果,可为高功率激光器和倍频器的设计提供理论依据。 相似文献
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位相光栅偏振特性的耦合波分析 总被引:1,自引:0,他引:1
基于麦克斯韦方程组和电磁场的边界连续条件,本文导出了位相光栅的严格的矢量耦合波衍射方程,指出了各级次衍射波之间存厢互耦合作用,并分析了光栅的偏振效应,得到光栅在不同偏振方式下的衍射特性,实验测试结果验证了理论分析和正确性。 相似文献
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高效全固化紫外四倍频激光器的研究 总被引:7,自引:0,他引:7
用半导体激光器抽运的调Q YLF倍频激光器抽运掺钛蓝宝石激光器,用LBO晶体在腔内产生二次谐波,再聚焦到BBO晶体上产生四次谐波深紫外激光。为了提高谐波转换效率,在腔内分别插入了单片、组合双折射滤光片和聚焦透镜,在平均功率为3.6W,波长为527nm的抽运光下得到410mW,417nm的蓝光。用长焦距的透镜聚焦二次谐波,得到34mW,208nm的紫外脉冲激光。从实验上详细研究了基频光的线宽对二次谐波效率的影响,二次谐波的线宽对四次谐波效率的影响、基频光的波长对四次谐波产生效率的影响。全面地分析了单片和组合大拆射滤光片及抽运功率对钛蓝宝石激光器基频光的脉宽、线宽等参量的影响。 相似文献
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Spectral domain analysis, scattering matrix analysis and PIC simulations are used here to design a second harmonic gyrotron cavity with an internal blazed grating which favors operation at the second harmonic of the electron cyclotron frequency rather than operation at the electron cyclotron frequency itself. Based on these simulations, the cavity design is optimized. The results show that a new gyrotron with higher power and higher frequency can be achieved by incorporating such a blazed grating. 相似文献
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激光束与其散射光束在晶体中发生非线性和频作用,在满足非共线相位匹配条件时,可观察到二次谐波环的现象。本文以拆射率主轴坐标xoz平面为例,推导出了双轴晶体中环参数的近似表达式。并用计算机得出了精确数值解,与实验观察到环的形状完全一致,提出了一种寻找最佳二次谐波产生方向的方法。 相似文献
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Second Harmonic Generation of Self Focused Cosh‐Gaussian Laser Beam in Collisionless Plasma 下载免费PDF全文
This paper presents an investigation of self‐focusing of a Cosh‐Gaussian (ChG) laser beam and its effect on second harmonic generation in collisionless plasma. In the presence of ChG laser beam the carriers get redistributed from high field region to low field region on account of ponderomotive force as a result of which a transverse density gradient is produced in the plasma which in turn generates an electron‐plasma wave at pump frequency. Generated plasma wave interacts with the incident laser beam and hence generates its second harmonics. Moment theory has been used to derive differential equation governing the evolution of spot size of ChG laser beam propagating through collisionless plasma. The differential equation so obtained has been solved numerically. The effect of decentered parameter, intensity of ChG laser beam and density of plasma on self‐focusing of the laser beam and second harmonic yield has been investigated. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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A new scheme with non-collinear sum frequency generation (SFG) process of broadband third harmonic generation (THG) with two KDP crystals (one doubler and one mixer) using angular dispersion was proposed. The principle of broadband harmonic generation with non-collinear angular dispersion was presented. The comparison between the schemes of non-collinear and collinear SFG process was performed. The effects of the angular dispersion on the conversion efficiency, the pulse shape and the spectrum of the third harmonic field were discussed. The results show that, if proper angular dispersion is added to the fundamental and the second harmonic field outside the mixing KDP crystal, respectively, the broadband third harmonic conversion efficiency can be improved significantly. However, the difficulty of this scheme arises due to the requirement of two gratings with different angular dispersion outside the mixer. With the new scheme, it can be simpler that only one grating is needed to realize the broadband phase matching in the non-collinear SFG process. Although the fundamental and the second harmonic field inside the mixing crystal are non-collinear except the center wavelength, a blazing grating with proper angular dispersion for the fundamental field (twice as that for second harmonic field) can yield the well compensation for phase mismatching in the SFG process. Consequently, the conversion efficiency and the characteristics of the third harmonic field for the broadband third harmonic generation can be improved significantly. 相似文献
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We carried out an analysis of the sensitivity of the method of intracavity laser spectroscopy with intracavity generation of the second harmonic to small frequency-independent losses evaluated by measuring the energies of laser-radiation pulses. We consider laser behavior with a constant and modulated quality factor of the cavity resonator. It is shown that the sensitivity of the method may be improved by an order of magnitude or higher by transforming the frequency of radiation and selecting the optimal parameters of the active medium pumping, nonlinear crystal, Q-factor of the cavity, and the means of its modulation. Measurement of the radiation power at the frequency of the second harmonic expands the range of laser-operation time regimes in which an increase in the sensitivity of the method is ensured. 相似文献