共查询到20条相似文献,搜索用时 31 毫秒
1.
Sub-picosecond chirped laser pulse-induced airflow and water condensation were investigated in a cloud chamber.The results indicate that the positively chirped sub-picosecond laser pulses generate a more uniform intensity distribution inside the plasma column, leading to a weaker airflow and an elliptic-shaped snow pile. The negatively chirped sub-picosecond laser pulses generate a spark-like intensity distribution inside the plasma column, which produces a wider range of airflow and a round snow pile. The amount of snow weight and the concentration of NO_3~- are found to be dependent on the intensity distribution inside the plasma column. The visibly stronger plasma column generates much more snow and a higher concentration of NO_3~-. These experimental results provide a reference for sub-picosecond laser-induced water condensation in realistic atmospheric conditions. 相似文献
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Chirp-dependent ionization of hydrogen atoms in the presence of super-intense laser pulses 下载免费PDF全文
《中国物理 B》2021,30(9):94209-094209
We perform a theoretical study on dynamic interference in single photon ionization of ground state hydrogen atoms in the presence of a super-intense ultra-fast chirped laser pulse of different chirp types(equal-power and equal-FWHM laser pulses) by numerically solving the time-dependent Schr ¨odinger equation in one dimension. We investigate the influences of peak intensity and chirp parameters on the instantaneous ionization rate and photoelectron yield, respectively. We also compare the photoelectron energy spectra for the ionization by the laser pulses with different chirp types. We find that the difference between the instantaneous ionization rates for the ionization of hydrogen atom driven by two different chirped laser pulses is originated from the difference in variation of vector potentials with time. 相似文献
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采用含时多态展开方法研究了高斯啁啾激光激发钾原子布局数跃迁的动力学过程,得到了不同激光脉冲强度、频率啁啾场中里德堡钾原子布局数跃迁,实现了布局数向目标态的跃迁. 相似文献
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T. Ulm A. Klehr G. Erbert F. Harth J. A. L’huillier 《Applied physics. B, Lasers and optics》2010,99(3):409-414
We report on the generation of 267 fs long pulses with a peak power of 661 W emitted by an InGaAs diode laser master-oscillator
power-amplifier (MOPA) system with an external grating compressor. The oscillator emits strongly chirped picosecond pulses
with several nanometer of bandwidth, which can be amplified without significant phase modulation and are compressed to femtosecond
pulses after leaving the amplifier. We used a diode laser module for asymmetric colliding pulse mode-locking and optimized
the collision point and the relative intensity of the counter-propagation pulses. 相似文献
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We have studied the effects of chirped femtosecond laser pulses on the formation of ultracold molecules in a Rb magneto-optical trap. We have found that application of chirped femtosecond pulses suppressed the formation of (85)Rb and (87)Rb(2) a(3)sigma(+)(u) molecules in contrast to comparable nonchirped pulses, cw illumination, and background formation rates. Variation of the amount of chirp indicated that this suppression is coherent in nature, suggesting that coherent control is likely to be useful for manipulating the dynamics of ultracold quantum molecular gases. 相似文献
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The spectral and temporal intensity distribution expression for the chirped femtosecond laser pulse diffracted by a rectangle reflection grating is derived. The effects of the chirped coefficient on the spatiotemporal and spectral characteristics are theoretically investigated in detail, and a criterion for judging whether or not the diffraction pulse is just split into two independent pulses in the temporal domain is obtained. The results show that the envelope curve of spectral intensity on the diffraction axis is more blue-shift, and its full width at e? 1 maximum is wider for bigger chirped coefficient. The principal maximum on the temporal axis can split into two independent principal maximums for enough height from the upper and the nether reflection surface of the grating. Each principal maximum splits into two smooth pulses, namely one principal pulse and one secondary pulse, and the secondary pulse gradually increases with the increasing of the chirped coefficient; the duration of two principal pulses increases with the increasing of the height of the upper and the nether reflection surface of the grating. 相似文献
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A new concept of a superpowerful femtosecond laser based on CPA in polycrystalline chromium doped ceramics (Cr:YAG, Cr:YSGG, etc.) pumped by a Nd:glass laser is proposed. In contrast to amplifiers in available petawatt laser systems (neodymium glass, titanium-doped sapphire, and parametric amplifiers with a DKDP crystal), these ceramics combine three key favorable properties: a large gain bandwidth to amplify chirped pulses with less than 20-fs durations, a wide aperture to amplify chirped pulses to the multikilojoule level, and a high conversion efficiency of narrowband Nd:glass laser pulses into chirped pulses. These properties open up the opportunity to create a unique laser with a peak power of 100 PW at a 10-kJ pump power. 相似文献
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对不同条件下强激光在空气中形成等离子体通道的三次谐波光谱特性进行了研究。单脉冲能量12 mJ,脉宽30 fs,重复频率10 Hz,中心波长795 nm的飞秒激光脉冲经0.5 m焦距的凹面镜聚焦,在空气中形成了等离子体通道, 并在前 向观测到谱线半峰全宽(FWHM)为15 nm的三次谐波。随着脉冲啁啾的变化,三次谐波的光谱出现红移或兰移,当激光脉冲附带+1.3×105fs2的二阶色散时,三次谐波谱线红移且谱峰强度增长了两倍。同时 ,通过改变可编程声光色散滤波器(AOPDF)光谱调制的位置(Hole position),三次谐波的光谱也发生频移。 相似文献
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Wu Zhao-Hui Wei Xiao-Feng Zuo Yan-Lei Liu Lan-Qin Zhang Zhi-Meng Li Min Zhou Yu-Liang Su Jing-Qin 《中国物理 B》2015,24(1):14211-014211
Chirped wideband pump and seed pulses are usually considered for backward Raman amplification(BRA)in plasmas to achieve an extremely high-power laser pulse.However,current theoretical models only contain either a chirped pump or a chirped seed.In this paper,modified three-wave coupling equations are proposed for the BRA in the plasmas with both chirped wideband pump and seed.The simulation results can more precisely describe the experiments,such as the Princeton University experiment.The optimized chirp and bandwidth are determined based on the simulation to enhance the output intensity and efficiency. 相似文献
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脉冲啁啾对于阿秒脉冲的影响 总被引:5,自引:5,他引:0
采用单电子近似和软核势模型, 通过数值求解一维含时薛定谔方程, 理论研究了当脉冲分别带有正、负啁啾的情况下所产生的阿秒脉冲.分析了不同脉冲啁啾特性对阿秒脉冲的强度和宽度的影响. 研究结果表明, 无论是正啁啾还是负啁啾, 随着啁啾量的增加, 都将使激光脉冲由产生单个阿秒脉冲趋向于产生阿秒脉冲链. 正啁啾和负啁啾对于阿秒脉冲宽度的影响是不同的, 负啁啾对于阿秒脉冲宽度影响很小, 适当的负啁啾有利于缩小阿秒脉冲的宽度; 而正啁啾脉冲产生的阿秒脉冲较无啁啾时展宽, 且随着啁啾量的增加, 其阿秒脉冲宽度迅速增大. 相似文献
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We present an evolutionary algorithm for reconstructing a femtosecond laser pulse from its interferometric autocorrelation trace and laser spectrum. The algorithm is optimized for the intensity and phase characterization of several-cycle optical pulses. We tested this algorithm with numerically-generated femtosecond pulses and then applied it to experimental data. In the experiment, a negatively chirped 31-fs pulse and a sub-10-fs pulse containing high-order phase distortion were characterized. Frequency-resolved optical gating measurements, performed for comparison, confirm the reliability of our technique. 相似文献
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When femtosecond laser pulses interfere with chirped femtosecond laser pulses in As2S3 fiber, a chirped fiber grating is formed. An analytical expression is given to describe the chirped grating, and its Bragg reflectivity is calculated. Because of the high photosensitive effect of As2S3 material, the chirped fiber grating has a wide Bragg reflective spectrum and high reflectivity by choosing proper parameters. This indicates that the chirped fiber grating can be used as a stretcher in the femtosecond chirped pulse amplification (CPA) system. 相似文献
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M. V. Ivanov S. V. Alekseev N. G. Ivanov V. F. Losev N. A. Ratakhin A. G. Yastremskii 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(9):1094-1098
The results from the generation and amplification of positively chirped pulses of 0.05 ns duration at a central wavelength of 475 nm in a THL-100 laser system are presented. It is found that the initial complex allows the generation of such radiation pulses with Gaussian intensity profiles and energies of up to 7 mJ. When such pulses with energies of 2–4 mJ are amplified in an XeF(C-A) amplifier, it is possible to achieve a saturation mode and obtain at the output laser beams with energies of up to 3.2 J. The possibility of compressing subnanosecond pulses at a wavelength of 475 nm in a compressor based on diffraction gratings is demonstrated. 相似文献
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Andreev A Lévy A Ceccotti T Thaury C Platonov K Loch RA Martin P 《Physical review letters》2008,101(15):155002
Recent significant improvements of the contrast ratio of chirped pulse amplified pulses allows us to extend the applicability domain of laser accelerated protons to very thin targets. In this framework, we propose an analytical model particularly suitable to reproducing ion laser acceleration experiments using high intensity and ultrahigh contrast pulses. The model is based on a self-consistent solution of the Poisson equation using an adiabatic approximation for laser generated fast electrons which allows one to find the target thickness maximizing the maximum proton (and ion) energies and population as a function of the laser parameters. Model furnished values show a good agreement with experimental data and 2D particle-in-cell simulation results. 相似文献
19.
We demonstrate an extension of forming a photorefractive volume grating in an Fe:LiNbO3 crystal by chirped intense femtosecond laser pulses generated from a Ti:Al2O3 regenerative amplifier at 1 kHz. We confirm that one-photon absorption is still dominant in the Fe:LiNbO3 crystal up to 70 GW/cm2. To generate a photorefractive grating at such a low laser repetition rate within a practical writing time, the laser pulse
intensity is increased to >30 GW/cm2. Furthermore, we demonstrate the amplification of femtosecond laser pulses by the chirped volume grating that is written
in the Fe:LiNbO3 by two-wave mixing. 相似文献