共查询到20条相似文献,搜索用时 142 毫秒
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对超短超强激光脉冲 (45fs,6× 10 17W /cm2 )与光致电离氦气形成的欠稠密等离子体相互作用中的二次谐波辐射进行了实验研究。测量了多种打靶强度的飞秒激光脉冲与不同气体密度氦气相互作用的二次谐波光谱 ,得到在欠稠密等离子体中二次谐波辐射与打靶激光能量的关系 ,分析了产生二次谐波辐射产生的物理机制 ,在考虑了强短脉冲激光电离气体产生的等离子体径向电子密度梯度因素 ,基于非线性作用过程的理论预期曲线与实验结果较好地吻合 相似文献
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采用含时密度泛函方法,结合赝势模型和电子交换相关作用的广义梯度近似,模拟了氮分子在超强飞秒激光脉冲作用下的高次谐波产生现象,并研究了激光脉冲偏振方向对氮分子高次谐波的影响.结果表明氮分子的高次谐波谱具有典型原子谐波谱的特征;谐波谱强度随着θ(激光偏振方向与分子轴向夹角)的增大而减小.这与J.Itatanl在Nature上报道的实验结果基本一致.
关键词:
含时密度泛函理论
激光偏振方向
高次谐波
氮分子 相似文献
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R. Spitzenpfeil S. Eyring C. Kern C. Ott J. Lohbreier J. Henneberger N. Franke S. Jung D. Walter M. Weger C. Winterfeldt T. Pfeifer C. Spielmann 《Applied Physics A: Materials Science & Processing》2009,96(1):69-81
Both the gas jet and the capillary setup have remarkable features for high-harmonic generation (HHG). We demonstrated both
the ability of the capillary to tailor its spectral XUV output in unique ways, as well as the feasibility of the jet and its
ability to produce photon energies up to the keV range. For maximizing the brilliance in both schemes we have successfully
applied the concept of self-learning loops to several of our experiments. We present current results on the focusability of
capillary high-harmonic radiation, a wave front measurement on gas jet high harmonics and measurements of the influence of
gas pressure and laser focus position on the divergence of gas jet high harmonics. This is embedded in an overview of selected
previous and current work of our group. 相似文献
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Villoresi P Ceccherini P Poletto L Tondello G Altucci C Bruzzese R de Lisio C Nisoli M Stagira S Cerullo G De Silvestri S Svelto O 《Physical review letters》2000,85(12):2494-2497
Harmonic radiation generated in a neon gas jet by sub-10-fs laser pulses was investigated both experimentally and theoretically. The spectral profile of the harmonics with respect to the order, their intensity and relative spectral shifts were measured as a function of the position of the gas jet. The results point out spectral features typical of the quasi-single-cycle excitation regime. A nonadiabatic three-dimensional numerical model was developed, which provides harmonic spectra in remarkable agreement with the experiments. 相似文献
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ZHONG Fangchuan DENG Jian QIN Ling HU Xueyuan ZHANG Zhengquan XU Zhizhan 《Chinese Journal of Lasers》1999,8(6):531-537
1 Introduction HighorderharmonicemissionofgasatominteractionwithintenselaserfieldisapromisingmethodtoproduceacoherentultravioletandsoftXraysource.Sincethefirstexperimentalobservationofthehighorderharmonicemissionofraregasesexposedtointenselase… 相似文献
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The phase-match and amplitude characteristics of high harmonics generation in gas filled micro-capillary have been analyzed. The results show that the order of harmonic can be selected by adjusting the gas pressure, the laser intensity and the inner diameter of capillary. The adjustment is depended on the dispersion properties of gas media . The amplitude of harmonics generated in gas filled capillary is two orders higher than that of gas jet, and the spectrum is become more monochromatic when the radius of the capillary is smaller. A high brightness tunable coherent soft X-ray source can be produced through interaction of fs intense laser with gas filled microcapillary. 相似文献
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Bernhardt B Ozawa A Vernaleken A Pupeza I Kaster J Kobayashi Y Holzwarth R Fill E Krausz F Hänsch TW Udem T 《Optics letters》2012,37(4):503-505
We present the first (to our best knowledge) femtosecond enhancement cavity in the visible wavelength range for ultraviolet frequency comb generation. The cavity is seeded at 518 nm by a frequency-doubled Yb fiber laser and operates at a peak intensity of 1.2×10(13) W/cm(2). High harmonics of up to the ninth order (~57 nm) are generated in an intracavity xenon gas jet. Intracavity high harmonic powers of several milliwatts for the third harmonic order and microwatts for the fifth harmonic order prove the potential of the "green cavity" as an efficient ultraviolet frequency comb source for future spectroscopic experiments. A limiting degradation effect of the cavity mirrors is avoided by operating at a constant oxygen background pressure. 相似文献
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Dobosz S Doumy G Stabile H D'Oliveira P Monot P Réau F Hüller S Martin P 《Physical review letters》2005,95(2):025001
In this Letter, we demonstrate the instantaneous creation of a hot solid-density plasma generated by focusing an intense femtosecond, high temporal contrast laser on an ultrathin foil (100 nm) in the 10(18) W/cm2 intensity range. The use of high-order harmonics generated in a gas jet, providing a probe beam of sufficiently short wavelengths to penetrate such a medium, enables the study of the dynamics of this plasma on the 100 fs time scale. The comparison of the transmission of two successive harmonics permits us to determine the electronic density and the temperature with accuracies better than 15%, never achieved up to this date in the regime of laser pulses at relativistic intensity. 相似文献
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This work continues our previous investigations on pulsed ejection of a dense plasma into a gas. The conditions for the formation of high-temperature (plasma) and low-temperature gaseous toroidal vortices during pulsed axisymmetric ejection of a dense plasma/gas into air are investigated experimentally at different parameters of the ambient medium and jet generator. Quantitative criteria for the formation and stable propagation of such vortices are established using experimental data. 相似文献
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C. de Lisio C. Altucci R. Bruzzese F. De Filippo S. Solimeno M. Bellini P. Foggi 《Applied physics. B, Lasers and optics》1997,64(3):323-330
We report the realization of a vacuum-ultraviolet radiation source based on high-order harmonic generation in noble-gas samples,
operating at high repetition rate. In particular, we observed up to the 13th harmonic (λ=61 nm) of the fundamental frequency
of a short pulse, high repetition rate titanium–sapphire laser after its interaction with a Xe gas jet. The effects of the
propagation of the fundamental and harmonic beams through an ionized medium are studied by analysing the spectral profile
of the 9th and 7th harmonics. Finally, we report a study of the dependence of the harmonic conversion efficiency on relative
position of the focus and the gas target.
Received: 29 March 1996/Revised version: 25 July 1996 相似文献
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A new method for electron acceleration in a gaseous medium is proposed and theoretically substantiated. The method is based on using a high-temperature gas domain (laser-induced jet, arc channel, etc.) as a source of runaway electrous with their subsequent acceleration in a dense low-temperature gas. It is shown feasible to obtain accelerated electron beams with currents as high as 1 kA and an average energy of approximately (2/3)eU (where U is the accelerating voltage), which is comparable to the parameters of the beams generated by accelerators on the basis of vacuum diodes. 相似文献
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We investigate how the intensity and duration of an attosecond pulse generated from high-order harmonic generation are affected by the pressure and thickness of the gas jet by taking into account the macroscopic propagation of both fundamental and harmonic fields. Our simulations show that, limited by the propagation effects, especially the absorption of harmonics, the intensity of an attosecond pulse cannot be improved by just independently increasing the gas pressure or the medium length. On the other hand, due to good phase-matching conditions, the duration of a generated attosecond pulse can be improved by changing the gas pressure. 相似文献