共查询到19条相似文献,搜索用时 140 毫秒
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研究了氦离子在中红外组合激光场作用下的高次谐波辐射和孤立阿秒脉冲的产生.研究结果表明,当主脉冲强度相对低时,谐波截止在657阶次处,形成一个宽度为287eV的连续谱.当主脉冲强度相对高时,可使谐波截止拓展到1795阶次,连续谱加宽到834eV.在两种情况下,我们实现了长量子路径选取,并且产生转换效率较高的连续谱.特别是对于相对高的激光强度,叠加450~1590阶次内任意87eV的谐波都可以直接得到50as以内的单个脉冲. 相似文献
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通过数值求解一维含时薛定谔方程,研究了多周期双色场与氢原子相互作用过程中不同波段的附加脉冲波长对体系高次谐波及阿秒脉冲产生的影响.研究发现,当双色场的附加脉冲波长处于红外波段1600 nm时,比起处于可见光波段的533 nm附加脉冲,谐波谱截止位置得到大幅延展,相应地拓宽了超连续带宽,小波变换后获得了78 as的孤立短脉冲.由合成电场的光学振荡频率解释了附加脉冲波段对谐波谱的影响,同时该结论有利于在获得孤立阿秒脉冲的研究中选择合适的附加脉冲频率. 相似文献
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研究了氦离子在中红外组合激光场作用下的高次谐波辐射和孤立阿秒脉冲的产生. 研究结果表明,当主脉冲强度相对低时,谐波截止在657阶次处,形成一个宽度为287 eV的连续谱. 当主脉冲强度相对高时,可使谐波截止拓展到1795阶次,连续谱加宽到834 eV. 在两种情况下,我们实现了长量子路径选取,并且产生转换效率较高的连续谱. 特别是对于相对高的激光强度,叠加450—1590阶次内任意87 eV的谐波都可以直接得到50 as以内的单个脉冲. 相似文献
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G. Chen J. G. Chen Y. J. Yang J. Q. Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(1):145-149
We numerically calculate the high-order harmonic generation (HHG)
power spectra from a one-dimensional model atom irradiated by linearly
polarised 12 fs two-colour laser pulses composed of a fundamental pulse from
Ti:sapphire laser and its second harmonic. It is found that a distinct
double plateau structure appears when the relative phase of the two pulses
is set as π/8, 2π/8 or 3π/8, and the double plateau structure
disappears when the relative phase is set as 4π/8, 5π/8, 6π/8
or 7π/8. The relative-phase-dependent plateau structure is explained by
the temporal profile of the synthesised electric fields as well as the
semi-classical “three-step” model. Moreover, our numerical result shows
that cut-off frequencies of the two-colour pulse HHG spectra can be exactly
predicted by use of the semi-classical “three-step” model. 相似文献
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We investigate theoretically the high-order harmonic generation driven by few-cycle laser pulses with intensities above the saturated intensity using the Lewenstein model. It is found that the carrier-envelope phase of the laser pulse has great influences on the coherence of the high-order harmonic spectrum in the plateau region when driven by a relatively weaker driver field in the oversaturated regime. While for a much higher intensity the coherence of the high-order harmonic spectrum is almost independent on the carrier-envelope phase. 相似文献
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本文数值计算了超短脉冲(脉冲持续时间为两个光学周期)的高次谐波发射功率谱.研究结果表明,超短脉冲谐波谱的截止频率不再符合IP 3.17UP的截止规则(IP为原子电离势,UP为有质动力能).对此,本文采用"三步"模型给出了合理解释,并用小波变换验证了结果的正确性. 相似文献
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Sansone G Benedetti E Caumes JP Stagira S Vozzi C Pascolini M Poletto L Villoresi P De Silvestri S Nisoli M 《Physical review letters》2005,94(19):193903
By using a self-referencing technique, we have experimentally measured the influence of the carrier-envelope phase of femtosecond light pulses on the phase of the electric field of the radiation produced by high-order harmonic generation. We show that, in particular experimental conditions, the temporal evolution of the electric field of the attosecond pulses, is directly controlled by the carrier-envelope phase of the driving pulses. 相似文献
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L. M. Kovachev 《Optical and Quantum Electronics》1992,24(1):55-66
Two mechanisms of self-confinement of wave packets on different carrying frequencies in monomode optical fibre are investigated. It is shown that the equations describing the processes possess a Hamiltonian structure. A new class of asymptotically free soliton solutions are found. Two spectral bandwidths for self-confinement of the optical pulses are determined. 相似文献
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This study reports the first experimental demonstration that two light pulses were made motionless and interacted with each other through a medium. The scheme with motionless light pulses maximizes the interaction time and can achieve a considerable efficiency even below single-photon level. To demonstrate the enhancement of optical nonlinear efficiency, the experiment in this study used the process of one optical pulse switched by another based on the effect of electromagnetically induced transparency. Moving light pulses activate switching at an energy per area of 2 photons per atomic absorption cross section as discussed in [Phys. Rev. Lett. 82, 4611 (1999)]. This study demonstrates that motionless light pulses can activate switching at 0.56 photons per atomic absorption cross section, and that the light level can be further reduced by increasing the optical density of the medium. The result of this work enters a new regime of low-light physics. 相似文献
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用时间延迟激光感生双光栅研究光路中的相位变化.实验结果表明,通过拍频信号峰值的位移,可以测量两束频率与偏振均不相同的光经过介质后相对相位的变化. 相似文献
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We present energy-resolved cross-correlation measurements of extreme ultraviolet (XUV) pulses generated as high harmonics of femtosecond pulses from a 1 kHz titanium-sapphire laser. The harmonic pulses are probed by a fraction of the fundamental laser pulse at 800 nm, in a noncollinear geometry, allowing us to vary independently the parameters of the harmonic pump and near-infrared probe pulses. We measure the so-called sidebands in the photoelectron spectrum of argon corresponding to the absorption of a harmonic photon plus or minus one probe photon. Spectrally resolving the cross-correlation signal allows us to characterize the time-dependent frequency of the XUV pulse.Received: 20 December 2002, Published online: 24 April 2003PACS:
42.65.Ky Harmonic generation, frequency conversion 相似文献