共查询到20条相似文献,搜索用时 31 毫秒
1.
P. A. Apanasevich 《Journal of Applied Spectroscopy》1967,6(3):216-221
The kinetic equations are used to show that induced Raman scattering can reduce the pulse height and length, and also can split a single pulse into several short pulses of decreasing energy. General formulas are derived for the pulse characteristics. 相似文献
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受激布里渊散射(SBS)具有脉冲压缩的特性,受激布里渊散射的脉冲宽度随着抽运能量的增大而变小,在水中可以达到几百皮秒的量级.本文在实验上观察到一种受激布里渊散射的脉冲宽度随抽运能量增大而变大的现象,这里称之为反常压缩.SBS的脉冲反常压缩和脉冲压缩与抽运光的强弱会聚情况有关.利用数值模拟,模拟了强弱会聚情况下抽运光在水中的传输规律,强弱会聚情况的抽运光对受激布里渊散射形成的有效增益长度不同:抽运光强会聚时有效增益长度短,形成SBS脉冲宽度的反常压缩;弱会聚时有效增益长度长,也就是正常的SBS脉冲压缩. 相似文献
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An experimental study of quantum mechanical pulse energy fluctuations in stimulated Raman scattering from hydrogen is presented. The probability density function P(W) for Stokes pulse energy W is measured for highly transient scattering in both the linear and nonlinear gain regimes. While large pulse energy fluctuations (100%) occur in the linear gain regime, the fluctuations are reduced to about 20% in the nonlinear regime where the laser pulse is depleted significantly. The results are in excellent agreement with the theoretical predictions of Lewenstein. 相似文献
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Linear Thomson scattering by a relativistic electron of a short pulse laser has been investigated by computer simulation. Under a laser field with a pulse of 33.3-fs full-width at half-maximum, and the initial energy of an electron of γ0=10, the motion of the electron is relativistic and generates an ultrashort radiation of 76-as with a photon wave length of 2.5-nm in the backward scattering. The radiation under a high relativistic energy electron has better characteristic than under a low relativistic energy electron in terms of the pulse width and the angular distribution. 相似文献
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Simultaneous stimulated Raman scattering at the 992 cm–1 and the 3063 cm–1 line of benzene is observed by mode-locked ruby laser pulse excitation. The double line stimulated Raman scattering is initiated by self-focusing. The influence of small-scale self-focusing, self-phase modulation, and cross-phase modulation on the double line stimulated Raman scattering is discussed. At low pump pulse intensities, before the onset of small-scale self-focusing, the steady-state Raman gain factors of both Raman lines are determined by Raman energy conversion efficiency measurements. 相似文献
6.
He-Ping Tan 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,87(2):175-192
It is not by isotropic scattering but by anisotropic scattering that radiant energy is redistributed in some materials containing real particles, fibers, or impurities. In some instances, great difference can be caused in transient thermal behavior between isotropic scattering and anisotropic scattering media. Ray tracing method combined with Hottel's zonal method is introduced to deduce thermal radiative source term for various optical boundary conditions induced by collimated incidence passing through translucent boundary. Temperature response caused by laser pulse at non-incident side of participating and anisotropic scattering media is examined. We investigate effects of scattering albedo, scattering phase function, initial temperature of media and thickness of media on temperature response. Results obtained for anisotropic scattering media are compared with those for isotropic scattering one and show that anisotropic scattering must be considered in the simulating measurement of thermophysical properties by the laser flash method for some materials with big scattering albedo which behave anisotropically, or big error will be introduced; forward scattering can increase excess temperature and backward scattering can decrease it at non-incident side of the considered sample irradiated by laser pulse. 相似文献
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从实验和理论上研究了受激布里渊散射(SBS)光脉冲波形.在Nd∶YAG调Q激光器中实验研究了SBS光脉冲波形随抽运光参数、结构参数和介质参数的变化规律,并利用SBS理论模型进行了数值模拟,实验与数值模拟结果的变化趋势基本一致.结果表明,抽运光能量越小,透镜焦距越短,镜-池间距越长,介质声子寿命越长,SBS光脉冲波形就越不容易出现调制现象.分析和讨论了抽运光参数、结构参数和介质参数对SBS光脉冲波形的影响机理.
关键词:
受激布里渊散射
脉冲波形
抽运光参数
结构参数 相似文献
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Dependence of parabolic pulse amplification on stimulated Raman scattering and gain bandwidth 总被引:4,自引:0,他引:4
An analytical model has been developed and verified by numerical simulations to determine limits induced by stimulated Raman scattering (SRS) on parabolic pulse evolution in high-power, high-energy Yb-fiber amplifiers. Our results show that the maximum achievable parabolic pulse energies are limited by SRS at low amplifier gains and by the finite gain bandwidth at high gains. Therefore, an optimum gain value exists that maximizes the achievable output pulse energy. 相似文献
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The focused ultrasound plays a role in localization and modulating the scattering light in ultrasound- modulated optical tomography (UOT). Both the modulation efficiency of the scattering light and the spatial resolution of UOT are determined by ultrasound. The effects of repetition frequency and pulse energy of impulse ultrasound on the modulated scattering light are derived through experiment in this letter. Purthermore, we compare the imaging sensitivity with 1, 2.25, 5, and 10 MHz center frequencies of impulse ultrasound. Experimental results demonstrate that better signal-to-noise ratios and higher sensitivities can be gained by use of more intense ultrasound and lower ultrasound frequencies. 相似文献
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分析了受激布里渊散射介质CCl4对纳秒激光脉冲的传输特性及功率限幅特性. 结果表明:透射脉冲波形随抽运光能量增加而压缩变形,脉冲前沿保持高斯型,后沿被压缩成功率“平台”,功率“平台”随抽运脉冲能量增加而逐渐变宽,但功率水平不变,表明该光学系统具有的功率限幅特性. 详细分析了功率限幅特性随抽运能量的变化规律和时间响应特性规律,采用脉宽为10ns、波长为1.06μm的Nd:YAG激光脉冲进行实验验证,理论与实验结论相符合.
关键词:
受激布里渊散射
功率限幅 相似文献
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DU Ying-Chao HUANG Wen-Hui HUA Jian-Fei HE Xiao-Zhong CHENG Cheng DU Tai-Bin TANG Chuan-Xiang LIN Yu-Zheng YUAN Xiao-Dong ZHANG Bao-Han ZHANG Xiao-Min WEI Xiao-Feng ZHANG Kai-Zhi LIU Cheng-Jun DENG Jian-Jun 《中国物理C(英文版)》2008,32(1)
The X-ray source based on Thomson scattering of ultrashort laser pulse with a relativistic electron beam is a means of generating a tunable, narrow bandwidth and ultrashort pulse of hard X-rays. Such a sub-picosecond hard X-ray source is proposed at Tsinghua University, and a preliminary experiment with a 16 MeV Backward Traveling electron linac and a 1.5 J, 6 ns Q-switched Nd:YAG laser is carried out first. A 6 ns pulse X-ray with a peak energy of 4.6 keV and an intensity of 1.7×104 per pulse is generated successfully in the experiment. The experimental setup, result and discussion are reported in this paper. 相似文献
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受激布里渊散射(SBS)作为三阶光学效应广泛应用于激光组束、分布式光纤传感、布里渊激光器等领域。近年来,SBS脉冲压缩亦得到特殊关注。基于布里渊放大过程中的能量转移特性,SBS脉冲压缩技术能够将ns量级脉冲压缩至亚ns量级,峰值功率可提升1~2个数量级。系统介绍了SBS脉冲压缩基本理论,综合论述了SBS压缩器结构、增益介质、泵浦脉冲等因素对脉冲压缩特性的影响,并对SBS脉冲压缩发展趋势进行了展望,为今后SBS特性的研究提供了有益参考,也为高重频、高能量激光的获取提供了可行方案。 相似文献
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应用多光子非线性Compton散射模型、空间动态补偿模型、非线性薛定谔方程和数值模拟方法,研究了Compton散射对超强飞秒激光等离子体中通道的影响,提出了将Compton散射光作为形成等离子体通道的新机制,给出了超强飞秒激光脉冲在等离子体中传播和电子密度随时间变化的非线性修正方程,并进行了数值模拟.研究发现:散射使等离子体中电子密度峰值增大1个量级,半径增大1 mm.激光最大功率密度被限制在10~(18)W/m~2以下,随传输距离增大缓慢衰减.传输初始阶段,单脉冲衰减能量较散射前增大2%,之后衰减较平缓.通过增加超强飞秒激光脉冲输入功率,能有效地增加电子密度峰值,有利于等离子体通道的形成.并对所的结论给出了初步物理解释. 相似文献
19.
R. Rosenfelder 《Zeitschrift für Physik A Hadrons and Nuclei》1975,274(3):267-273
A systematic eikonal expansion for the scattering of high-energy electrons from nuclei is derived which starts from the iterated Dirac equation. The resulting scattering amplitude is written in an impact parameter representation depending on eikonal phases which are proportional to inverse powers of the energy. The first two correction terms to the leading Glauber-Baker amplitude are calculated. For a Coulomb potential they agree with a sinθ-expansion of the relativistic Coulomb scattering amplitude. In the case of scattering from an extended charge distribution at sufficiently high energies numerical partial wave calculations are accurately reproduced. 相似文献
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应用多光子非线性Compton散射模型、空间动态补偿模型、非线性薛定谔方程和数值模拟方法,研究了Compton散射对超强飞秒激光等离子体中通道的影响,提出了将Compton散射光作为形成等离子体通道的新机制,给出了超强飞秒激光脉冲在等离子体中传播和电子密度随时间变化的非线性修正方程,并进行了数值模拟。并研究发现:散射使等离子体中电子密度峰值增大1个量级,半径增大1mm。激光最大功率密度被限制在1018W/m2以下,随传输距离增大缓慢衰减。传输初始阶段,单脉冲衰减能量较散射前增大2%,之后衰减较平缓。通过增加超强飞秒激光脉冲输入功率,能有效地增加电子密度峰值,有利于等离子体通道的形成。并对所的结论给出了初步物理解释。 相似文献