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Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse

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Chinese Physics B 2024年第3期33卷 433-440页

作者：王源李玉龙乔月高娜郭福明陈洲赫兰海杨玉军赵曦王俊 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy Jilin UniversityChangchun 130012China Beijing Institute of Space Launch Technology Beijing 100076China School of Physics and Information Technology Shaanxi Normal UniversityXi'an 710062China

We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping *** findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping *** phenomenon holds potential significance for experimental setups necessitating precisely tuned single ***,we observe a modulated shift in the created harmonic photon energy,spanning an impressive range of 1.2 *** frequency peak shift is rooted in the asymmetry exhibited by the rising and falling edges of the laser pulse,directly influencing the position of the peak frequency *** study quantifies the dependence of this tuning range and the asymmetry of the laser pulse,offering valuable insights into the underlying mechanisms driving this ***,our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is *** attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return *** observation introduces an innovative approach for generating semi-integer order harmonics,thus expanding our understanding of high-order harmonic ***,our work contributes to the broader comprehension of complex phenomena in laser-matter interactions and provides a foundation for harnessing these effects in various applications,particularly those involving precise spectral control and the generation of unique harmonic patterns.

关键词： high-order harmonic semi-integer-order spectra shift inhomogeneous field

Generation of quasi-chirp-free isolated attosecond pulses from atoms under the action of orthogonal two-color combined pulse of fundamental frequency and higher intensity second harmonic fields

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Chinese Physics B 2023年第6期32卷 218-225页

作者：蔚瑞贤乔月李萍王俊陈基根冯伟郭福明杨玉军 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy(Jilin University) Changchun 130012China Zhejiang Provincial Key Laboratory for Cutting Tools Taizhou UniversityJiaojiang 31800China

The intrinsic chirp of high-order harmonic generation is an important factor limiting the production of ultrashort attosecond *** on numerically solving the time-dependent Schrodinger equation,the generation process of highorder harmonic from the He atom under the action of orthogonal two-color combined pulse of fundamental frequency and higher intensity second harmonic fields is *** this paper,we propose to achieve quasi-chirp-free isolated attosecond pulses by superimposing a higher second-harmonic field on the orthogonal direction of the fundamental frequency *** is found that the high-energy part of its harmonic emission exhibits small chirp characteristics,which can be used to synthesize isolated attosecond *** the analysis of the wave packets evolution and the classical motion trajectories of the electron,it is demonstrated that the quasi-chirp-free harmonic can be attributed to the simultaneous return of electrons ionized at different times to the parent *** influence of the relative phase of the two pulses on the harmonics is further analyzed,and it is observed that this phenomenon is sensitive to the relative phase,but it can still generate isolated attosecond pulses within a certain phase.

关键词： high-order harmonic orthogonal two-color fields relative phase quasi-chirp-free isolated attosecond pulses

Two-center interference in high-harmonic generation of H2%＋ in a combination of a mid-infrared laser field and a terahertz field

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Chinese Physics B 2017年第1期26卷 176-181页

作者： Jun Zhang Xue-Fei Pan Tong-Tong Xu Hong-Dan Zhang Hui Du Jing Guo Xue-Shen Liu Institute of Atomic and Molecular Physics Jilin University Changchun 130012 China

We theoretically investigate the two-center interference in high-order harmonics generated from the H2-＋ in a combination of a mid-infrared laser and a terahertz field by numerically solving the time-dependent Schr ¨odinger equation（TDSE）.The interference minima in high-order harmonic generation（HHG） are effectively suppressed when a THz field is *** contribution to HHG from the two separate nuclei is used to demonstrate the locating order of the harmonic ***, we also investigate the emission time of harmonics. The results show that the intensity of the short path around 60^th order after adding a THz field is stronger than that in the mid-infrared laser field, which further illustrates the suppression of the interference minima in HHG.

关键词： terahertz field high-order harmonic two-center interference

Supercontinuous high harmonic generation from asymmetric molecules in the presence of a terahertz field

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Chinese Physics B 2011年第4期20卷 345-349页

作者：杜洪川王慧巧胡碧涛 School of Nuclear Science and Technology Lanzhou University Institute of Modern Physics Chinese Academy of Sciences

We have investigated high-order harmonic generation from asymmetric molecules. It is found that supercontinuous high harmonics, which are produced from asymmetric molecules by significantly steering the ionization, are broken down when the electric field of the 5-fs driving laser pulse is increased to 0.16 a.u. The high harmonic generation from asymmetric molecules with the presence of a terahertz field is also investigated. This reveals that the terahertz controlled laser pulse significantly increases the energy difference between photons, emitted from the ejected electrons, in the first and second halves of the optical cycle at the centre of the driving laser pulse. In this way, a 200-eV broadband supercontinuum can be produced in the plateau, from which a 60-as pulse with a bandwidth of 60 eV can be directly obtained with a minor post-pulse.

关键词： high-order harmonic attosecond pulse supercontinuum

Experimental study of conversion from atomic high—order harmonics to x—ray emissions

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Chinese Physics B 2003年第5期12卷 524-527页

作者： WangQi ChenJian-Xin XiaYuan-Qin ChenDe-Ying NationalKeyLaboratoryofTunableLaserTechnology HarbinInstituteofTechnologyHarbin150001China

There are two physical phenomena in a strong laser intensity. One is the high-order harmonic emission; the other is x-ray emission from optical-field ionized plasmas. The experiment of conversion from high-order harmonics to x-ray emissions was given with a 105fs Ti:sapphire laser by adjusting laser intensities. The ingredient in plasma was investigated by the numerical simulations. Our experimental results suggested that the free electrons have detrimental effects on harmonic generation but are favourable for x-ray emission from optical-field ionized plasmas. If we want to obtain more intense harmonic signals as a coherent light source in the soft x-ray region, we must avoid the production of free electrons in plasmas. At the same time, if we want to observe x-rays for the development of high-repetition-rate table-top soft x-ray lasers, we should strip all atoms in the plasmas to a necessary ionized stage by the optical-fieldionization in the field of a high-intensity laser pulse.

关键词： high-order harmonic x-ray emission experimental conversion

Extension of harmonic Cutoff and Generation of Isolated Sub-30 as Pulse in a Two-Color Chirped Laser Field

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Communications in Theoretical Physics 2012年第10期58卷 557-564页

作者：张刚台白婷婷张美光 Department of Physics and Information Technology Baoji University of Arts and Sciences Department of Mathematics Baoji University of Arts and Sciences

We theoretically investigate high-order harmonic and isolated attosecond pulse generation in a two-color chirped laser field,which is synthesized by a 9 fs/800 nm fundamental chirped pulse and a 9 fs/1600 nm controlling chirped *** numerical results show that,by using this method,not only is the harmonic cutoff significantly extended to the 948th order harmonic,but also the bandwidth of the supercontinuum spectrum is effectively broadened to about 1342 *** addition,due to the introduction of the chirp,the long quantum path is suppressed and only the short one is selected,and then an isolated 28 as pulse with a bandwidth of 155 eV is obtained directly.

关键词： high-order harmonic attosecond pulse generation supercontinuum two-color chirped field

Generation of an extreme ultraviolet supercontinuum with a multicycle chirped laser and a static electric field

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Chinese Physics B 2012年第11期21卷 271-279页

作者：张刚台白婷婷张美光 Department of Physics and Information Technology Baoji University of Arts and Sciences Department of Mathematics Baoji University of Arts and Sciences

We theoretically present a method for generating an ultrabroad extreme ultraviolet （XUV） supercontinuum by using the combination of a multicycle chirped laser and a static electric field. At a low laser intensity, the spectral cutoff is extended to the 495th order harmonic, and the bandwidth of the supercontinuum spectrum is broadened to 535 eV. At a high laser intensity, the harmonic cutoff is enlarged to the 667th order, and a supercontinuum covering a bandwidth of 1035 eV is generated. In these two cases, the long quantum path is removed, and the short quantum path is selected. Especially for the relatively high laser intensity, an isolated 23-attosecond pulse with a bandwidth of about 170.6 eV is directly obtained. Finally, we also analyze the influences of the chirp parameter and the duration of the chirped pulse as well as the static field strength on the supereontinuum.

关键词： high-order harmonic attosecond pulse generation supercontinuum combined field

Isolated sub-30-attosecond pulse generation using a multicycle two-color chirped laser and a static electric field

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Chinese Physics B 2014年第4期23卷 230-239页

作者：张刚台 Department of Physics and Information Technology Baoji University of Arts and Sciences

We present a theoretical investigation of high-order harmonic generation in a chirped two-color laser field, which is synthesized by a 10-fs/800-nm fundamental chirped pulse and a 10-fs/1760-nm subharmonic pulse. It is shown that a supercontinuum can be produced using the multicycle two-color chirped field. However, the supercontinuum reveals a strong modulation structure, which is not good for the generation of an isolated attosecond pulse. By adding a static electric field to the multicycle two-color chirped field, not only the harmonic cutoff is extended remarkably, but also the quantum paths of the high-order harmonic generation （HHG） are modified significantly. As a result, both the extension of the supercontinuum and the selection of a single quantum path are achieved, producing an isolated 23-as pulse with a bandwidth of about 170.6 eV. Furthermore, the influences of the laser intensities on the supercontinuum and isolated attosecond pulse generation are investigated.

关键词： high-order harmonic attosecond pulse generation supercontinuum combined field

Amplitude and rotation of the ellipticity of harmonics from a linearly polarized laser field

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Chinese Physics B 2022年第10期31卷 88-95页

作者： Ping Li Na Gao Rui-Xian Yu Jun Wang Su-Yu Li Fu-Ming Guo Yu-Jun Yang Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy(Jilin University) Changchun 130012China

We simulate the dynamic response of H^(+)_(2) in a linearly polarized laser field by numerically solving the time-dependent Schr?dinger *** elliptically polarized high-order harmonics generated by H^(+)_(2)irradiated by the linearly polarized laser field are systematically *** result shows that the amplitude and rotation of the ellipticity of harmonics are affected by the alignment angle and internuclear distance of the *** the change in forces acted on the ionized electrons and the trajectories of the electrons,the phenomena are found to be due to the change in the direction of the total Coulomb forces from the two nuclei felt by the recollided ionized electrons in the direction perpendicular to the laser polarization *** on the influence law,we can select the harmonics with a specific frequency band under different alignment angles and then synthesize the isolated attosecond pulses with different rotations,which can be continuously converted from right-handed circular polarization,linear polarization,and left-handed circular polarization by changing the alignment *** study provides a new possible approach to the real-time detection of molecular states by using attosecond pulses and obtaining more optimized harmonics with molecular properties.

关键词： high-order harmonic ellipticity rotation attosecond pulses