共查询到20条相似文献,搜索用时 31 毫秒
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M. L. Petukh V. A. Rozantsev A. D. Shirokanov A. A. Yankovskii 《Journal of Applied Spectroscopy》2000,67(6):1097-1101
We compare radiation of plasma flares produced on exposure of metals to laser radiation in a monopulse generation mode in the case of single and double pulses with change in air pressure. For double pulses, we established an increase in the duration and intensity of the radiation of spectral lines and also an analogy between the change in their intensities and those of single pulses obtained at a reduced air pressure. 相似文献
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应用电子汤姆孙散射的经典理论,通过理论分析和计算机模拟,研究了超短超强激光脉冲作用下电子产生的辐射脉冲的性质.计算表明,在这种情况下,电子的辐射通常以阿秒脉冲列的形式出现.讨论了不同激光场参数(包括激光强度、脉宽、初相位和偏振态)、不同电子初始状态(初始速度和位置)对辐射脉冲的时间和空间特性的影响.通常在相对论光强条件下,激光强度越大,电子辐射越强,脉宽越窄,中心频率越大,并且方向性越好;电子在线偏振激光中产生的辐射效率,比在同样强度下圆偏振激光中产生的效率更高;无论入射光是线偏振光,还是圆偏振光,辐射场呈现较复杂的偏振态, 并且它与辐射方向有关.当电子具有一定的初始能量时,通常辐射场的振幅随电子初始能量的增大而增大.不管电子的初始能量以及运动方向如何,做相对论运动的电子产生的辐射趋向于出现在靠近电子运动方向的角度区域. 相似文献
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Terahertz (THz) radiation has attracted much attention due to its wide potential applications. Though radiation can be generated with various ways, it is still a big challenge to obtain strong tabletop sources. Plasma, with the advantage of no damage limit, is a promising medium to generate strong THz radiation. This review reports recent advances on strong THz radiation generation from low-density gases and high-density solid targets at different laser intensities. 相似文献
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The asymmetric photoionization of atoms irradiated by intense,
few-cycle laser pulses is studied numerically. The results show that
the pulse intensity affects the asymmetric photoionization in three
aspects. First, at higher intensities, the asymmetry becomes
distinctive for few-cycle pulses of longer durations. Second, as the
laser intensity increases, the maximal asymmetry first decreases
then increases after it has reached a minimal value. Last, the value
of the carrier-envelope phase corresponding to the maximal asymmetry
varies with the pulse intensity. This study reveals that the
increasing of pulse intensity is helpful for observing the
asymmetric photoionization. 相似文献
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The optical rectification of ultrashort laser pulses with a titled amplitude front in LiNbO3 crystal is studied theoretically. It is shown that the results of calculation are in reasonable agreement with experimental data. 相似文献
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Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters. We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution. 相似文献
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L. Torrisi S. Gammino A. M. Mezzasalma C. Gentile J. Krsa L. Lska K. Rohlena J. Badziak P. Parys J. Wolowski 《Applied Surface Science》2003,220(1-4):193-202
The high power pulsed laser Prague asterix laser system (PALS), operating at the fundamental (1ω) and third (3ω) harmonics (1315 and 438 nm wavelengths, respectively), is employed in a single-shot mode to irradiate tantalum targets in vacuum. The laser pulse width is 400 ps and the laser pulse energy ranges between 43 and 736 J at 1ω and between 12 and 230 J at 3ω. High ablation yields (0.1–0.6 mg per pulse) are measured as a function of the laser pulse energy at both wavelengths; at 438 nm higher etching rates are observed. The produced craters are analysed by the scanning electron microscope (SEM) and by the high sensitivity surface profiler system. They are investigated in dimension, shape and angle aperture as a function of the incident laser energy. Different possible mechanisms responsible for the different crater shapes are presented and discussed. 相似文献
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Nikoletta Jegenyes Zsolt Toth Jozsef Klebniczki Costas Fotakis 《Applied Surface Science》2006,252(13):4667-4671
The bonding structure of carbon films prepared by pulsed laser deposition is determined by the plasma properties especially the change of the kinetic energy. Using double laser pulses the ablation process and the characteristics of the generated plasma can be controlled by the setting of the delay between the pulses. In our experiments, amorphous carbon films have been deposited in vacuum onto Si substrates by double pulses from a Ti:sapphire laser (180 fs, λ = 800 nm, at 1 kHz) and a KrF laser system (500 fs, λ = 248 nm, at 5 Hz). The intensities have been varied in the range of 3.4 × 1012 to 2 × 1013 W/cm2. The morphology and the main properties of the thin layers were investigated as a function of the time delay between the two ablating pulses (0-116.8 ps) and as a function of the irradiated area on the target surface. Atomic force microscopy, spectroscopic ellipsometry and Raman-spectroscopy were used to characterize the films. It was demonstrated that the change of the delay and the spot size results in the modification of the thickness distribution of the layers, and the carbon sp2/sp3 bonding ratio. 相似文献
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G. L. Yesayan K. A. Palanjyan T. G. Mansuryan A. S. Zeytunyan L. Kh. Mouradian 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2008,43(1):23-26
Based on the numerical and experimental studies, a nonlinear-spectronic character of similaritons formed in a single-mode optical fiber without gain is demonstrated. It is shown that the combined action of the Kerr-type nonlinearity and normal dispersion of the fiber leads to the formation of similaritons. The temporal envelop, spectral and phase profiles of such similaritons have a nearly parabolic shape in their central energy-carrying parts. 相似文献
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本文叙述了用半导体激光器产生光脉冲的基本原理,介绍了用电脉冲驱动AlGaAs/GaAs双异质结激光器产生ps光脉冲的线路原理及实验结果。 相似文献
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W. L. Liang B. K. A. Ngoi L. E. N. Lim K. Venkatakrishnan C. W. Hee 《Optics & Laser Technology》2003,35(4):285-290
In this paper, integration of interference phenomenon into femtosecond laser micromachining was reported as the femtosecond laser pulses were reshaped spatially to perform ablation. The generation of circular interference pattern was demonstrated by overlapping infrared femtosecond laser pulses. The interference pattern was subsequently focused on a copper substrate to ablate microstructures of concentric circular rings. The present technique is expected to open up new applications in the areas of rapid fabrication of micro-Fresnel lenses, hybrid microlenses and lens arrays. 相似文献
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Liu Zhenlin Ohtake Hideyuki Izumida Shinji Ono Shingo Sarukura Nobuhiko 《Optical and Quantum Electronics》2000,32(4-5):521-529
The THz-radiation power from InAs reaches sub-mW level in a 1.7-T magnetic field irradiated with femtosecond laser pulses of 1.5-W average power. The THz-radiation power is related almost quadratically both to the magnetic field and to the excitation laser power. Furthermore, the THz-radiation spectrum is found to be controlled by the excitation pulsewidth, chirp direction of the excitation pulse, and the magnetic field. 相似文献
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本文分析了在联合原子方案下高于Ip+3.2Up的超高次谐波发射效率极低的主要因素:除电子间的排斥作用外,更重要的原因乃是在通常情况下外来电子在非母离子中没有布居.据此,提出了一个有效解决这个难题的组合激光脉冲方案,从而将高达Ip+8Up的超高次谐波的发射效率提高了三个数量级以上. 相似文献
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本文应用一维双温激光靶相互作用简化物理模型对脉宽为10ns级系列脉冲激光照射真空中铝靶产生的LSD波进行了数值研究。对于单个脉冲宽度τ_p=10ns,脉冲间距τ_p=50ns的系列脉冲情况,得到了LSD波点火的脉冲个数N_(LSD)与单脉冲归一化强度(I_s/I_(LSD))的关系。分析了系列脉冲激光LSD波点火的积累效应以及LSD波的屏蔽效应。 相似文献
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V. V. Ivanov A. V. Koutsenko A. A. Matsveiko Yu. A. Mikhailov A. I. Popov G. V. Sklizkov A. N. Starodub 《Journal of Russian Laser Research》2004,25(4):349-360
An amplification scheme for ultrashort laser pulses of high radiation contrast was used to perform experiments on ablation pressure symmetrization using a prepulse upon acceleration of thin foils. It is shown that the spontaneous radiation of the regenerative amplifier restricts the energy contrast in the amplification of chirped pulses at a level of 10-4–10-3. The possibility of direct amplification of a short pulse with a view to increasing the energy contrast ratio was considered. Experiments were performed on the PICO laser facility to demonstrate that a 10-ps pulse amplification achieved an intensity 100 GW/cm2, a gain factor of 1.2, and an inversion dumping factor >30%. 相似文献
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用经典辐射理论对线偏振周期量级激光脉冲的线性Thomson散射进行分析,从理论上得到它可产生亚阿秒脉冲的结论. 计算显示,在电子相对论因子为50、激光脉冲中心波长为1μm、归一化光场强度为0.01的情况下,用包含1.5个光周期的激光脉冲,可获得0.2as(半高全宽)的散射脉冲输出. 还对光场载波包络初相φce和电子进入光场的初相φin对散射脉冲的影响作了分析讨论,结果表明,在适当的φce和φin条件下,能实现单个阿秒脉冲输出,并可对脉冲宽度和频率进行调谐.
关键词:
线性Thomson散射
周期量级激光脉冲
载波包络初相
阿秒脉冲 相似文献